Design Guidelines

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Chapter Three — Design Guidelines

Design Guidelines

TABLE of CONTENTS SECTION ONE: Design Process Guidelines ...... 3.2 SECTION TWO: Destiny of the West Design Guidelines ...... 3.4 SECTION THREE: Community and Urban Context Guidelines ...... 3.6 SECTION FOUR: Highway Facilities Guidelines ...... 3.14

UNLANDSCAPE ARCHITECTURE & PLANNINGLV RESEARCH

Purpose Chapter Three — Design Guidelines

PURPOSE OF DESIGN GUIDELINES The guidelines, accompanied by concept dia- How to Use the Design Guidelines grams, sketches, or photographs, demonstrate The Design Guidelines are divided into four sec- Design Guidelines provide the framework for im- ways in which to achieve the design intent. tions as described below. The full design team as proving the aesthetics of existing, new, and retro- well as potential partnering entities, such as com- fit highway projects. They are written statements NDOT will review each project design for consis- munities and other organizations, should be fa- of recommended methods to meet the segment tency with these guidelines and the overall Land- miliar with each section. design objectives. These guidelines are not stan- scape and Aesthetics Corridor Plan. The full de- dards; however, they represent a vision for land- sign team – NDOT staff, communities, engineers, 1) Design Process Guidelines scape and aesthetics across Nevada’s highways. project managers, landscape architects, consul- Describe the necessity of integrating landscape and aesthetics at the beginning tants, contractors, and maintenance crews – is of every project. strongly encouraged to: Guidelines approach corridor aesthetics as a com- 2) Destiny of the West Guidelines prehensive effort, intentionally avoiding a proj- Describe the vision, components, and ect-to-project approach. Guidelines assist in the • Become familiar with design guidelines for management plan for the Destiny of the the design segment in which a project is development of design. Adherence to the guide- West design segment associated with located. The guidelines direct the design Lake Mead, Hoover Dam, and Boulder City. lines in planning, design, and operations accom- toward creating aesthetic unity within the 3) Community and Urban Context Guidelines plishes the following goals: design segment. Describe guidelines for facilities and • Understand the site context. The land- amenities that are primarily influenced by • Interpret the design themes of each landscape surrounding the proposed project local communities, depending on right-of- scape design segment – including predominant materials, colors, way extents. and structures, as well as natural and cul- • Create visual unity among all highway 4) Highway Facilities Guidelines tural resources and social elements – pro- structures and facilities Describe guidelines that are primarily vide direction for enhancement. • Select finishes, color palettes, and surface influenced by NDOT’s standards including patterns that are compatible with the sur- • Seek early review of the project. Changes structures, grading, roadside services, and rounding landscape are much easier to make at the beginning construction practices. • Incorporate transportation art motifs and of the project than at the end. Involving media that represent the landscape design others early in the planning/design process segment themes helps ensure that the project is both eco- nomically and aesthetically feasible. (1), (2) The Design Guidelines have been divided into two major categories: those that are directed toward community-based enhancements and those related to highway facilities improvements.

3.1 Chapter Three — Design Guidelines SECTION ONE: Design Process Guidelines

SECTION ONE: 1.0 PROJECT DESIGN PROCESS 1.3 Understand the site context, including the LANDSCAPE AND AESTHETICS IS NOT AN 1.1 Integrate landscape and aesthetics at the on- surrounding landscape, and conduct a com- AFTERTHOUGHT TO ENGINEERING, BUT Design Process set of the planning, design, and engineering prehensive analysis. THE STARTING POINT FOR INTEGRATED, Guidelines phases of all highway projects. CONTEXT-SENSITIVE SOLUTIONS. Landscape and aesthetics should not be an • Conduct a comprehensive site analysis for each project. The site inventory for each afterthought to a highway project. project should extend beyond project These guidelines describe the necessity of inte- boundaries to analyze the site and sur- • Landscape and aesthetics are an integral rounding landscape. Ensure the planning grating landscape and aesthetics at the beginning part of the planning, design, and engineer- and design of the highway project respond of every project. ing of all highway projects. to this comprehensive analysis. • NDOT’s structure inventory report regard- • Consider characteristics such as precipita- ing type, size, and location of highway tion, topography, ground cover, size and structures should include information location of plant material, visual condi- on landscape and aesthetics. It should tions, soils, site drainage, rock outcrop- (1) Understanding the existing conditions and also provide justification for proposed pings, and other natural features that are context of the corridor is a critical part of the design process. structures that do not meet the design located on, and surrounding, the site. Ad- guidelines. ditionally, archaeological and cultural re- • Engineering design should incorporate sources and categories, such as historical landscape and aesthetics to create high- settlement, are important. way structures and facilities that are effective, safe, and aesthetically appealing.

1.2 Understand the design segment theme and select design concepts that interpret the theme.

(2) Computer simulation of a planned highway • Review the vision and objective for the at the conceptual phase of the project. landscape design segment as described in the Corridor Plan and ensure that the theme guides the project design • Understand the site context, including the viewshed analysis and landscape design segment objectives described within the Plan • Ensure project design successfully interprets the landscape design segment theme (3) Photo simulation of a highway project helps visualize the physical design.

3.2 SECTION ONE: Design Process Guidelines Chapter Three — Design Guidelines

1.4 Use a variety of sketches, three-dimen- • Design new projects that are low sional modeling, and other tools to visual- maintenance. ize and detail the highway. • Consider maintenance routines required for the design program, and identify ar- As the level of design progresses from gen- eas that may need additional attention. eral to specific, highway layout and facilities • Create maintenance agreements with should be visualized through a variety of local agencies as necessary to establish methods to create a high quality system. appropriate practices and levels of maintenance over the life of the project. 1.5 Visualize design concepts in three dimensions. Plan view design does not accurately represent the experience of the traveler along the highway or illustrate issues of visual design. Therefore, it is important to understand design concepts in their three-di- mensional framework.

• Utilize sketches, models, and digital visualization tools. “Roadway Explorer” is an excellent tool to utilize for this purpose.

1.6 Consider landscape and aesthetics costs in conjunction with baseline costs. Landscape and aesthetics should be considered simultaneously with a project’s capital budget and estimates. In addition to determining a project’s baseline construction cost, allocation of budgets and resources for landscape and aesthetics should be clearly outlined at the start of a project.

1.7 Estimate maintenance costs during design to calculate the total life cycle cost for landscape and aesthetic treatments. (4) Utilizing several different methods of design study and visualization results in an Maintenance is a key component to integrated and context sensitive solution. the success of landscape and aesthetic treatments.

3.3 Chapter Three — Design Guidelines SECTION TWO: Destiny of the West Design Guidelines

SECTION TWO: 1.0 DESTINY OF THE WEST DESIGN PRINCIPLES Destiny of the West 1.1 Create an environmentally sensitive high- Design Guidelines way that preserves the scenic quality of the Hoover Dam area. The vision is organized around the idea that the road is an integral part of the landscape. Guidelines described under the Destiny of the As such, it should respond to and be respect- West Design Principles set the vision of highway ful of the land and the spirit of place. The aesthetics for roadways within and entering into experience and importance of the highway the Boulder City/Hoover Dam area. These guide- should include the surrounding Eldorado lines are in addition to the community and urban and River Mountains, Lake Mead, Colorado context and highway facilities guidelines de- River, Mojave Desert plants, wildlife, and res- scribed in sections three and four. idents of Boulder City. The road should serve as a model for highways, providing access to highly utilized recreation destinations while maintaining an elevated level of environmental sensitivity. An opportunity exists (1) Enhanced guidelines and treatment levels should be used to reinforce the cultural and natural significance of the Destiny of the West design segment. for the alignment, design, and construction of the Hoover Dam and Boulder City Bypass to follow these guidelines and serve as an example of context-sensitive highway design.

1.2 Utilize enhanced guidelines for nationally significant areas. An elevated standard is applied to areas of national significance. Hoover Dam and its surrounding landscape represent an important piece of United States history and displays a very high level of scenic quality. Therefore, a foundational landscape type of accentuated hardscape with native revegetation softscape should exist for the Hoover Dam sub-segment, located within the Destiny of the West Landscape Design

Segment. Features such as concrete barri- (2) Much of the land adjacent to this corridor is owned by (3) The Hoover Dam’s historic and national importance ers, retaining walls, and drainage elements federal agencies. Partnerships are necessary to manage demands an accentuated level of treatment for all design. long-term scenic quality. 3.4 SECTION TWO: Destiny of the West Design Guidelines Chapter Three — Design Guidelines

should feature aesthetic treatments that re- 1.4 Partner with existing federal agencies to cre- spond to the landscape setting. Additional spe- ate a consistent vision and manage the high- cific guidelines describing elevated treatments way for long-term scenic quality. for this section of roadway are included within US 93, near Hoover Dam, is not recommended the individual guideline sections. for scenic byway designation because the majority of land adjacent to the roadway is under 1.3 Design components of the Destiny of federal ownership. However, coordination with the West. the federal agencies involved is critical to de- Due to the high level of tourism and recreation veloping a comprehensive vision for the cor- at the Hoover Dam, a coordinated system of ridor. Individual management plans should be rest areas and viewpoints should be established consulted to identify and address any conflict- and linked by shared-use trails. The rest area ing ideas. Eventually, an overall management should include a state welcome center that plan should be created through a team-based (1) The scenic quality of the Destiny of the West segment is especially valuable and should be presented to visitors works in concert with the Hoover Dam inter- approach that clearly defines methods to pro- through a coordinated system of rest areas and viewpoints. pretive facility and provides additional travel tect and enhance the roadway’s defining sce- information for the state of Nevada. This sys- nic and environmental qualities. tem will establish specific areas for travelers to park and experience the scenic beauty of the area and help ease congestion resulting from roadside parking and sight-seeing.

A system of specific signage and interpretive elements can promote awareness of the historical importance and environmental aspects of this area. Welcome centers, rest areas, and scenic viewpoints provide an excellent venue for signage and information that enhances the visitor experience and understanding of the area.

Wildlife habitat corridors should be incorporated throughout the highway’s design and retro- fits should occur to increase connectivity.

3.5 Chapter Three — Design Guidelines SECTION THREE: Community and Urban Context Guidelines SECTION THREE: SECTION TABLE of CONTENTS Community and Urban 1.0 Community Gateways ...... 3.7 Context Guidelines 2.0 Community-based Street Systems ...... 3.8 3.0 Sidewalks ...... 3.9 4.0 Street Trees and Planting Strips ...... 3.10 5.0 Graphics and Signage ...... 3.13 These guidelines include facilities that are primarily influenced by local community desires but may benefit from NDOT’s support. A community’s highway is important and serves as a primary component of the public realm. Even though NDOT is not responsible for facilities outside of the right-of- way, it recognizes the need to work with local jurisdictions to create context sensitive solutions.

NDOT understands the need for flexibility, and it functions as a facilitator in supporting a community’s vision and goals for the highway. The guidelines found in this section are meant to enhance established traffic engineering and road design practice. No single solution will transform a community’s highway through downtown. Rather, communities should carefully evaluate and consider several options, thoroughly understanding the issues at hand in order to create a highway that fulfills the collective goals of the partnership established between the community and NDOT. Neither NDOT nor the community can accomplish the goals on their own.

3.6 SECTION THREE: Community and Urban Context Guidelines Chapter Three — Design Guidelines

1.0 COMMUNITY GATEWAYS Highlight community entrances with clear 1.1 Establish gateways that clearly express and attractive signage, using landscape ma- community identity. terials that reflect the community character. Gateways are highly visible areas specially Execute the design in a clear, consistent, and designed and maintained to convey the first bold manner. Repetition of the design is the impression and identity of neighborhoods, basis for the unique identity of the corridor. communities, towns, cities, and regions. • Signage should be appropriately sized • Provide an impressive visual aesthetic and incorporated into an architectural or sculptural element consistent with the • Utilize appropriate landscape and/or community’s character, the environmen- structural techniques to screen unsightly tal context, and the corridor’s theme. land uses • Landscape plantings should include lay- ers of low water-use plant material ar- 1.2 Integrate the gateway into the highway ranged to enhance the architectural ele- facilities. ments and reinforce the transition into the community. Gateways should be part of a larger design intent, coordinate with community (1) A thoughtful combination of hardscape and softscape elements will enhance community gateways. facilities, and use materials that are found 1.4 Locate gateways at likely future growth throughout the town. Refer to Softscape boundaries. and Hardscape Types and Treatments (pag- Community gateways mark the entrances/ es 1.3-1.9) and Softscape Type Guidelines exits and designate the transition to in- (pages 3.40-3.46), for more details about the creased development. Gateways marking types of features and plants to consider for downtowns may be used to improve com- community gateways. munity identity and draw motorists into the heart of town. • Community gateways need to be integrated with highway structures and • Downtown gateways should complement landscape. the community gateway while reflecting • Architectural elements may include trans- the special character of the city center. portation art, rock walls, accent lighting, and signage. (2) Artistic sculptural elements add a focal touch to 1.5 Engage agencies and organizations in the community gateways. • Utilize bridges to establish community identity. planning and design process. • Ensure that community gateways are Engage applicable state and local agencies, distinctive, memorable, and functional. as well as local stakeholders and organizations in the planning, design, and imple- (3) Entry monuments that can be recognized from a 1.3 Ensure community gateways contribute to mentation of community gateways. distance introduce travelers to upcoming communities. community identity and clearly define community identity points.

3.7 Chapter Three — Design Guidelines SECTION THREE: Community and Urban Context Guidelines

2.0 COMMUNITY-BASED STREET Truck traffic requires more space for turn- MANAGE LANDSCAPE COMMUNITY TRANSITION SYSTEMS ISSUES ing movements and increases noise levels and CHARACTER • Zone between down town 2.1 Consider improvements to the surrounding fumes within the community. Wide streets • Areas of growing or and undeveloped edge planned development cuts • Curb and cross st reets street system before widening the highway discourage pedestrian activity and can harm • Indications of potential generously spaced through communities. the town’s economic potential. community expansion • Buildings set back from right- of-way Wide streets discourage pedestrian activity in an otherwise natural setting • Vehicular and pedestrian • Diverting truck traffic away from the local needs are balanced and have a negative economic impact. Sec- • Vehicular needs main street may distribute traffic loads • Pedestrian crossings at ondary streets that are not performing well dominate this zone more evenly and improve the function of signalized intersections influence the way in which a highway oper - • Infrequent pedestrian lane• Bike or shar ed-use path the main street. crossings easily integrated ates as a community main street. Improve- • Vehicular traffic should continue through • Frontage roads are • Buildings have parking in ments to other major and minor streets im - main street where feasible in order to sup - common front to• Low mid cost treatments pact the functionality of a main street. port community businesses and facilities. • Low cost treatments are appropriate are appropriate BOULDER • Parallel streets should have few interrup - CITY tions and maintain a fairly direct connec- • Traffic improvements should be consid- tion that may be improved to accommo- US 93 ered in context with surrounding trans- date truck traffic. portation patterns. Improvements to other streets allow potential lane width reductions along the highway and pro - 2.4 Avoid bypasses and only use them in limited vide additional space for landscape and applications. aesthetics. N Bypasses are utilized to divert traffic around • Improvements to surrounding city streets (1) As highways travel through communities, the function of the road changes from high speed automobile travel to may include utilizing parallel streets, communities, particularly when heavy traf - pedestrian-oriented main streets. implementing a truck bypass, improving fic conditions obstruct the functionality the local street network, and using paral - of main street. However, bypasses reduce lel, one-way streets. the interaction between travelers and communities. 2.2 Shorter blocks encourage pedestrian activ - ity and provide more corner lots, essential • A bypass may work in certain cases where for local businesses. the highway is designated as part of the Short blocks with connecting streets char- freight system or heavy traffic volumes overload a well-designed street system. acterize traditional main streets. • If a bypass is used, maintain connectivity for bicyclists and pedestrians and provide • Where possible, utilize short blocks of up direct connections back to community to 400 feet to encourage pedestrian ac - business districts. (2) Parallel one-way street systems may tivity in downtowns. be used to improve traffic patterns and provide additional space for landscape and pedestrian improvements. 2.3 Consider routing trucks onto a parallel street and encourage automobile traffic through main street.

3.8 SECTION THREE: Community and Urban Context Guidelines Chapter Three — Design Guidelines

3.0 SIDEWALKS 3.4 Use distinctive paving to highlight sidewalk 3.1 Provide a 10 to 15 foot sidewalk width for areas immediately adjacent to the inside downtown areas where possible. face of curb. A wider sidewalk allows for more pedestrian Sidewalk areas can be organized into two activities along the street. zones – the amenity zone and the pedestrian zone. The amenity zone is adjacent to • Additional width may be required to ac- the curb and should be a minimum of two commodate transit shelters, outdoor feet, but preferably four feet or greater, de- dining, and retail. (1) Eight foot sidewalks allow two-way pending on the sidewalk width. pedestrian traffic and minimal street • A sidewalk may be eight feet wide in con- furnishings. strained circumstances. Minimum side- (5) Wider sidewalks allow for a broad range of pedestrian walk width is six feet. • Distinctive paving treatments may be amenities such as benches, lighting, and outdoor dining. used in this area to distinguish it from pedestrian movement areas. 3.2 Provide continuous sidewalks throughout • Treatments should be consistent over a downtown areas. block length, but may vary from block to The ability of pedestrians to access and block. move through downtown areas depends on • Street trees, planters, benches, transit shelters, signs, utility poles, and other el- the connectivity of sidewalks and paths, as ements are located in the amenity zone. well as appropriate design and placement of (2) Ten foot sidewalks provide • Elements should be grouped together or enhanced user comfort and space. crosswalks. placed in a way that leaves a minimum open area of eight feet between them, allowing passage from the sidewalk to the • Establish connections to other sidewalks (6) Important road intersections and pedestrian or path systems where town centers street. crossings can be identified with stamped concrete or transition into suburban or rural areas. changes in paving material. 3.5 Provide pleasant seating opportunities 3.3 In town centers, provide pedestrian ame- along every block in the downtown area. nities (benches, drinking fountains, transit Seating is essential in a comfortable pedes- shelters, kiosks, trash receptacles, newspa- trian environment. (3) 12 foot sidewalks allow room for per racks, banners, and decorations). outdoor dining and sidewalk displays. Streetscapes that appear lively and inviting at- • Arrange seating to accommodate a vari- tract travelers and support local businesses. ety of views. • Locate benches and gathering spaces to absorb sun on cold days and provide shade • Street furnishings should be consistent on hot days. with surrounding architectural styles and the overall landscape segment theme. • Ensure that communities commit to maintain and clean street furniture as part of • Maintain a minimum five feet of clear maintenance agreements that are negoti- space around street furniture to accom- ated prior to construction. modate pedestrian movement. (7) Continuous sidewalks, street trees, and pedestrian • Provide wide sidewalks and curb exten- (4) 15 foot sidewalks create space for amenities are part of a complete main street system that sions as locations for benches. high levels of pedestrian activity. enhances community character and pedestrian safety. 3.9 Chapter Three — Design Guidelines SECTION THREE: Community and Urban Context Guidelines

3.6 Consider under-grounding utilities to provide • Locate bus pull-outs on the far-side loca- additional space for sidewalk enhancements. tion of intersections. Utilities should be consolidated to minimize • Minimize conflicts between vehicles, pas- sengers, pedestrians, and cyclists poles and other sidewalk obstructions.

• Coordinate signage with utility poles 3.8 Consider using artistic paving and historical where feasible. marker insets to accentuate downtown areas. • Avoid placing signs and utilities in pedestrian areas. • Celebrate distinctive areas with accentuated paving materials. 3.7 Incorporate transit shelters to promote pe- • Consult artists for ideas to improve the destrian and non-motorized transportation community downtown. (NMT) opportunities. • Paving patterns should coordinate with intersection designs and overall commu- Coordinate transit stops with local transpor- nity character (see illus. 2). tation agencies or Metropolitan Planning Organizations (MPO).

(1), (2) Enhanced paving patterns set within a main street environment show community character and cue pedestrians toward safe circulation.

4.0 STREET TREES AND PLANTING STRIPS • Consider common insect and disease prob- 4.1 Carefully select plant species. lems that consistently require maintenance, or are life threatening. • Maintain storefront visibility and reduce pe- • Select trees that thrive in the local climate destrian conflicts by selecting trees whose and consider species whose roots, seasonal form remains intact when limbed up seven flowers or fruit will not disrupt sidewalks to eight feet. • Evaluate trees based on site-specific charac- • Consider tree height over traffic lanes. Can- teristics as well as design intent. opies should appear natural when trimmed • Considerations for physical characteristics in- to 13 feet. clude form, height, spread, height to canopy • Select plants that will provide a variety of or- bottom, canopy density, trunk size, root habit, namental characteristics, such as seasonal rate of growth, and longevity. color, texture, bark, and foliage. • Consider habitat requirements affecting • Plant species according to the softscape type plant growth, including soil type, soil oxy- and treatment designated by the design ob- gen deficiency resistance, salt resistance, jectives. irrigation need, shade tolerance, heat tolerance, air pollution resistance, and wind re- • Avoid planting a single species in subur- sistance. ban areas due to the risk of a single pest or disease that could destroy an entire street • Minimize maintenance costs by avoiding trees tree planting. with excessive maintenance requirements in- (1) Low maintenance, drought-resistant plant materials are ideal selections for median and sidewalk plantings cluding flowers, foliage, fruit, and twigs. along this corridor. 3.10 SECTION THREE: Community and Urban Context Guidelines Chapter Three — Design Guidelines

• Downtown districts may be highlighted 4.4 Utilize hanging baskets, containers, and through a formalized street tree pattern. other vertical elements where feasible. In areas of limited rights-of-way, hanging 4.2 Properly place trees in sidewalk conditions. baskets, moveable planters, and other verti- Maximize the lifespan of trees to reduce cal elements may be used to provide struc- the cost of tree replacement. ture or to accent street tree plantings.

• Protect trees from damage by car doors. • Hanging baskets may be incorporated Where on-street parking is provided, al- into the street design and attached to low adequate room between trees and light fixtures or buildings to provide vi- cars (two feet minimum, three feet to sual relief and enhance the aesthetics. four feet ideal). Trees may be placed • Baskets may be replaced with wreaths or between parking spaces to minimize other seasonal accents during dormant damage. seasons. Allow for root aeration and potential water • • Moveable planters add flexibility to the harvesting through the use of tree wells streetscape design. (four foot by four foot minimum, five foot by five foot ideal). Dry-set pavers may also • Avoid placing containers within clear be used, ensuring adequate root aeration. zones and immediately adjacent to curbs where high levels of heat and vehicle ex- • Consider light placement as part of tree haust are more prevalent. spacing and placement (typically 25 feet (1) This mixed line of street trees aids in wayfinding and provides much needed shade in the desert climate. to 40 feet). • No container should be used if planter widths exceed 25% of the entire side- Place trees so they do not block vehicular • walk width. site lines or building accessways. Main- tain visibility of traffic signals, directional • Select neutral container colors that har- signage and access to entry drives. monize with brick pavers, concrete sidewalks, most building facades, and the countless color combinations produced 4.3 Street tree plantings may be varied to dis- by annual plantings. tinguish downtown areas from transition • Container design should be simple and zones and accentuate wayfinding. understated. • Use a consistent planter type within com- (3) Strategically-located bike racks make Small trees in combination with medium and alternative means of transportation more munities and provide groupings where large trees can reinforce wayfinding in towns. convenient. possible. Containers should be sited near street corners (as long as clear visibility is • Distinctive trees may be used within maintained for drivers), to flank entranc- downtown areas to distinguish them es to landmark buildings, or to physically from other commercial areas. and visually define outdoor café spaces. • Key intersections and gateways may be • Combined height of containers and designated by clustering smaller trees or plantings should not obstruct the view of other distinctive groupings. either motorists or pedestrians at street intersections and access drives.

(2) The use of a continuous line of street trees in a downtown (4) Tree grates protect trees from unwanted root environment improves visual connectivity and place making. compaction along street environments. 3.11 Chapter Three — Design Guidelines SECTION THREE: Community and Urban Context Guidelines

4.5 Buffer sidewalk from the roadway through 4.7 Use engineered planting soil for street tree the use of planting strips or raised planters plantings. where possible. Trees planted in urban conditions and as Planting strips provide opportunities to ab- part of street tree programs face unique sorb runoff water and decrease overall drain- challenges. The soil under adjacent side- age requirements. walks and roadways is typically compacted to support the paving. This compaction in- • Where space is not required for widened hibits root growth and spread, causing shal- sidewalks or on-street parking, provide low root growth and tree stress. Engineered planting strips (ideal five feet minimum width) or raised planters (see illus. 1). planting soils include mixtures of soil, loam, • Planting strip design should consider stone, water, and a moisture-retaining poly- the placement of benches, signs, bicycle mer or sand that transfers weight-bearing racks, and other street furniture. loads from stone to stone in the gravel, leav- • Raised planters should incorporate seat ing the soil between the stones unaffected walls to provide additional pedestrian by compaction. This type of engineered soil seating. creates a larger rooting volume with in- • Consider providing three feet of hard surface between planting strips and parallel creased porosity, nutrient-holding capacity, on-street parking to accommodate mo- and drainage for a healthier environment for (1) Planting strips (five foot minimum width) provide (2) Using a variety of species protects plantings from torists upon exit from their vehicles. aesthetic enhancement and increase pedestrian safety disease and creates a more visually interesting street tree root growth. by buffering sidewalks from the roadway. quality.

4.6 Ensure that communities commit to main- • Engineered planting soils should be used tain and provide irrigation for streetscape around root balls of street trees. plantings. • Continuous trenches of engineered The success of a streetscape program within planting soil are recommended between street trees. communities requires dedication to mainte- • Locate trenches parallel to curbs and un- nance and irrigation of planted areas. der non-mortared brick pavers. Trenches provide greater volumes of soil for root • Streetscape plantings should not be pro- growth and permit air and water to reach vided without community endorsement tree zones. and support. • Avoid spray irrigation systems where possible, and do not overspray onto walkways and into gutters. • Irrigation and maintenance may be funded through community beautifica- tion committees and other community organizations. (3) Moveable elements such as concrete planters and benches allow for flexibility within the sidewalk system.

3.12 SECTION THREE: Community and Urban Context Guidelines Chapter Three — Design Guidelines

5.0 GRAPHICS AND SIGNAGE 5.4 Use distinctive signage to direct motorists 5.1 Create a standard system of signage that through the heart of the community. aids wayfinding within communities while Truck traffic is often not desirable within also providing information about local fa- downtown areas and separate truck routes cilities and organizations. may be established. Vehicular and tourist traffic, however, is sought after. • Provide a coordinated signage system that reflects the distinctive character of • Ensure that signage appropriately directs special districts. vehicular traffic to promote tourism and • Graphics can take the form of signs, ban- support local businesses. ners, information kiosks, or pavement in- scriptions or inlays. 5.5 Coordinate light fixture design with graph- • Materials and designs should be clear and simple, so as to be easily read and quickly ics and signage. understood by pedestrians or motorists, as appropriate. • Banners may be incorporated into light fixtures and should be considered as part of the design. Graphics should be consis- 5.2 Locate and size signage and graphics so that tently displayed. they are easily read and understood by both (1), (2) Banners and signage can be used to advertise community events and amenties. These should be displayed in a • Customized light fixtures reinforce con- consistent manner with lighting elements and directly incorporated onto light poles when possible. cars and pedestrians. text-sensitive solutions.

• Pedestrian-scaled signage should be 5.6 Utilize a consistent color palette within lo- placed at heights that can be easily seen from the sidewalk (see illus. 3). cal communities. • Signage designed for motorists can be Local jurisdictions may choose a color pal- larger, and placed at heights and intervals ette for fixtures and amenities that corre- that can be easily seen and understood at sponds with the community’s vision. higher traveling speeds. • Colors should respond to the natural set- 5.3 Provide community graphics such as ban- ting and subtly enhance the community ners to promote special events and define without overpowering the streetscape design. special districts and neighborhoods. • Color should complement the NDOT col- or palette for structures within the right- • Create a coordinated system of signage of-way. that describes community events and reinforces community character. • Banners that span the roadway should be used sparingly and in more commercial locations. Banners can be installed per- (3) A wayfinding map placed at a highly visible manently, or as seasonal and temporary downtown location can be an important device to forms of signage. guide tourists to local businesses.

3.13 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

SECTION FOUR: SECTION TABLE of CONTENTS 1.0 Welcome Centers and Non-interstate Statewide Gateways ...... 3.15 Highway Facilities 2.0 Rest Areas, Viewpoints, and Pull-offs ...... 3.16 Guidelines 3.0 Transportation Art ...... 3.19 4.0 Signage ...... 3.21 5.0 Color Palette Application ...... 3.23 6.0 Roadway Design ...... 3.24 These guidelines pertain to highway facilities that 7.0 Medians ...... 3.25 are primarily influenced by NDOT’s standards, in- 8.0 Pedestrian Crossings ...... 3.26 cluding structures, grading, roadside services, and 9.0 Non-motorized Transportation Systems (NMT) ...... 3.28 construction practices. The guidelines found in this 10.0 Bridges ...... 3.29 section are meant to enhance established traffic 11.0 Noise Reduction and Walls ...... 3.32 engineering and road design practice. No single 12.0 Concrete Barriers and Guardrails ...... 3.34 solution will transform the highway. Partnerships 13.0 Lighting ...... 3.35 may be created with communities and other agen- 14.0 Fencing ...... 3.36 cies and organizations to accomplish landscape 15.0 Grading and Retaining Walls ...... 3.36 and aesthetic treatments in addition to support- 16.0 Rock Cut and Excavation ...... 3.37 ing landscape and aesthetic elements that impact 17.0 Drainage ...... 3.38 areas outside of the right-of-way. Established part- 18.0 Erosion Control ...... 3.38 nerships and design teams should carefully evalu- 19.0 Water Harvesting ...... 3.39 ate and consider several options and thoroughly 20.0 Irrigation ...... 3.40 understand the issues at hand in order to create a 21.0 Softscape Types and Treatments ...... 3.40 highway that fulfills their collective goals. Neither 22.0 Wildlife Crossings and Protection ...... 3.47 NDOT, communities, nor other agencies or organi- 23.0 Construction Practices ...... 3.48 zations can accomplish the goals on their own. 24.0 Maintenance Facilities and Practices ...... 3.49 25.0 Recommendations for Sustainable Highway Environments ...... 3.50

3.14 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

1.0 WELCOME CENTERS AND NON- INTERSTATE STATEWIDE GATEWAYS 1.1 Provide a vibrant, visually rich welcome center at Boulder City. Promote and provide information about statewide travel opportunities and services. Promote the welcome center as an important civic facility, and ensure that it maintains a strong visual presence. The gateway welcome center should convey the identity of Nevada, ensuring that the entry experience is notable and memorable. Welcome centers should also signify departure from Nevada, leaving the traveler with a positive memory. Program components offered at centers include interpretation of time, history and the Mojave Desert landscape. Con- duct a feasibility study to determine the ap- (1) The gateway at the California-Nevada border along US (2) Use of existing materials and patterns in 95 should consist of simple design elements. propriate location for the welcome center statewide gateways accentuate connection to place and history. and potential partnerships for construction, operation, and maintenance.

1.2 Provide non-interstate statewide gateway fe atures crafted from the land and place where US 95 enters Nevada from California. Use local materials and vernacular forms in combinations that subtly reinforce the character of the local landscape. Non- interstate gateway features should be understated and relate to the scale of the road. Each statewide gateway feature shall include the Nevada name and state seal, feature stone material from local sources, and use planting types identified in the landscape design segment.

(3) Welcome centers should present local culture, materials, and architecture in a dramatic fashion to communicate the region’s identity and attract visitors. 3.15 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

2.0 REST AREAS, VIEWPOINTS, AND PULL-OFFS • Avoid using makeshift, adapted site facilities 2.1 Provide a comprehensive roadside service with no distinctive architectural style. program. • Concrete barriers and brightly painted pole bollards should not be used for parking de- Roadside services are key components of the high- lineation or site boundaries at rest areas and way corridor, particularly where long distances pull-offs. separate developed areas. Provide a comprehen- • Sustainable architecture may be appropriate sive roadside service program throughout the for many highway service areas where water, energy, and landscape resources are difficult corridor. The road services matrix on the opposite to secure and maintain. page describes varying levels of service stops and • Provide lighting in scale with the site associated program elements. Refer to the Specif- development. ic Corridor Features maps (pages 2.17, 2.18, 2.27, • Articulate space, frame views, and provide 2.36) for potential road service facility locations. shade with landscape plantings and/or architectural features. • Locate rest areas to provide safe stopping points. 2.3 Retrofit existing rest areas. • Connect rest areas located in highly utilized Analyze existing rest area structures, buildings, recreation areas with a shared use trail. amenities, and layout for their visual interest. • Incorporate facilities for transit stops where Renovate to improve the aesthetics and user necessary. (1) Using architecture to frame scenic views helps connect visitors to the larger landscape. comfort of existing road service facilities. • Buffer roadside services from the highway, or provide an access road when located off the highway. 2.4 Locate viewpoints and points of interest to take • Consider major site resources and features advantage of visual access to the features of such as topography, views and vistas, unique interest. vegetation, geological features, wetlands, and other qualities native to the site and its Give special attention to existing or potential surroundings. views, vistas, and cultural or historical attractions • Consider siting activity pull-offs where they that are unique to the site or have outstanding provide access to activities located adjacent resource value, such as Native American heri- the highway. tage and emigrant history. Locate viewpoints at • Locate truck parking so as to not disrupt views the following locations: and other features.

• Eldorado Valley (US 95) 2.2 Ensure rest area design reflects the local setting. • Hoover Dam (US 93) All rest areas, viewpoints, and pull-offs should • Railroad Pass (US 95) readily accommodate travel needs and reflect • Kyle Canyon (US 95) the corridor’s design theme. • Lee Canyon (US 95) • Indian Springs (US 95) • Utilize vernacular forms and local materials to (2) Viewpoints should be placed at key viewing areas, (3) Road service facilities that use local materials and create rest areas that blend seamlessly with and built with materials and forms reflective of their color palettes blend into the landscape and maintain the surrounding landscape. surroundings. the unique character of the place. 3.16 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

ROAD SERVICES MATRIX Description Landscape Treatment Program Elements

ROADSIDE Roadside pull-offs provide facilities for drivers to exit the highway for a brief • Native plant revegetation to en- • Site-specific interpretive signage period. Facilities and minimal parking are provided to accommodate the ab- hanced native landscape types • No toilets or running water PULL-OFF • Trash containers breviated stay. (Referred to as “Rest Stop” under former NDOT naming conven- • Standard hardscape type • Limited car and Recreational Vehicle parking tions.) • Scenic overlooks • Located according to unique or outstanding features • Shade canopy (vegetation or structure)

VIEWPOINTS Viewpoints and points of interest present opportunities to view unique vistas, • Native plant revegetation to en- • Located according to travelers’ needs and unique site features geologic and historic features, or cultural landmarks. Interpretive elements are hanced native landscape types • Site-specific interpretive signage AND POINTS • Toilets/no running water integrated into the site design, and Place Name Signage and Travel Information • Standard to accentuated hardscape • Handicap accessible OF elements are provided to establish the relationship between highway and place. types • Picnic tables and shade structures • Trash containers INTEREST Typically, the length of stay is short and parking is limited. • Paved car and Recreational Vehicle parking • Telescopes/viewfinders • Nature walks or short trails • Seating Areas • Shade canopy (vegetation or structure) BASIC REST Basic rest areas are located throughout the state offering site specific inter- • Enhanced native landscape type • Located according to traveler’s needs • Paved car and Recreational Vehicle parking pretive information. They offer limited restroom facilities and may or may not • Standard to accentuated hardscape and unique site features • Paved truck parking AREA AND • Site-specific interpretive signage • Nature walks or short trails include running water, depending on availability. Typically, these rest areas are types • Toilets/no running water • Seating Areas COMMUNITY located adjacent to scenic views, unique historical, cultural or environmental • Emergency call box • Shade canopy (vegetation or structure) • Handicap accessible • Local community information REST AREA features. Community rest areas provide facilities within the town’s infrastruc- • Picnic tables and shade structures ture and function as a pocket park or town square. • Trash containers COMPLETE Complete rest areas are typically located at 60-mile intervals throughout the • Regionally adapted landscape type • Regional interpretive signage • Recreational Vehicle dump station state and are usually situated outside of developed areas. They feature fully- • Focal hardscape type • Running water and flushing toilets • Paved car and Recreational Vehicle parking REST AREA • Emergency call box and telephones • Paved truck parking operable facilities in combination with interpretive information on regionally • Drinking fountains • Telescopes/viewfinders significant cultural and historical sites. Complete Rest Areas also provide trav- • Vending machine services (at manned • Interpretive and overlook features sites) • Children’s play area elers with picnic facilities and include children’s play areas and pet areas. • Handicap accessible • Pet rest facilities • Picnic tables and shade structures • Shade canopy (vegetation or structure) • Trash containers • Local community information • Bicycle storage units

GATEWAY Gateway facilities convey first impressions and identity. Special features may • Regionally adapted landscape type Program elements are consistent with the type of Road Service Area provided. be incorporated to highlight the area through design interpretation of the • Landmark hardscape type REST AREA Specific elements include: place. Gateways may be associated with any level of rest stop in the listing. The • Regional services information incorporation of local community information regarding amenities, events and • Interpretation of regional sites and features • Information on regional recreational attractions interpretative elements, improves the interface between the highway and the communities it serves.

WELCOME Welcome centers are located along major entry routes to the state. They offer • Regionally adapted landscape type • Located at major entry routes to state • Trash containers introductions to the state and travelers can find access to useful travel infor- • Landmark hardscape type • Informational Services • Bicycle storage units CENTER • Staffed visitor center • Paved car and Recreational Vehicle parking mation. Welcome centers include a staffed information kiosk. • State-wide interpretive signage • Paved truck parking • Running water/flushing toilets • Improved trails • Emergency call box and telephones • Children’s play area • Drinking fountains • Pet rest facilities • Vending machine services • Shade canopy (vegetation or structure) • Handicap accessible • Telescopes/viewfinders • Picnic areas and shade structures

3.17 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

• Design the viewpoint to reflect the surrounding setting and unique features. • Coordinate the preservation and management of scenic vistas and unique features with the appropriate organizations and groups. • Evaluate viewpoints periodically to ensure the integrity of the view. • Consider the use of scenic easements to protect views and vistas. • Limit the construction of outdoor advertising and other elements and structures that detract from the quality of the landscape. (2) Connections to regional trail systems can be incorporated (3) Self-weathering materials should be used for at recreational gateways, viewpoints, and rest areas. architectural elements at rest areas and viewpoints.

2.5 Coordinate locations of rest areas with recreational access points. Coordinate locations of rest areas with regional trail systems.

• Coordinate with appropriate agencies to provide informational signage for recreational activities. • Coordinate the location of park-and-ride Point of most significant views lots, rest areas, and activity pull-offs with Trail (4) Local materials and colors can be used to integrate (5) Shade structures should be designed to disappear in transit stops to encourage use of public parking areas into the natural setting. their surroundings. transportation, particularly in areas of heavy tourist traffic. Trail

2.6 Provide community rest areas within designated towns.

Community rest areas have the dual benefit Parking of serving as town parks and engaging trav- Return to highway Landscaping materials signal elers with local businesses. entry and exit points

Earth-shaping and • Develop community rest areas through vegetation to block views and screen highway noise cooperative agreements with local municipalities. • Provide information about local and re- (1) Prototypical viewpoint / point of interest. (6) Interpretive signage included along trails inform (7) Viewpoints that are elevated from the ground can be gional activities, businesses, and points of travelers about their surroundings. used to attract visitors. interest.

3.18 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

3.0 TRANSPORTATION ART 3.3 Ensure artwork expresses an excellence of crafts- 3.1 Engage artists early in the design and develop- manship, quality, truthfulness, and originality. ment stages of highway projects to ensure an in- Transportation art should complement the overall tegrated and comprehensive art program. design of highway facilities. Materials and forms Transportation art should not be an afterthought should be carefully considered to ensure the long- or decoration. term suitability of the project.

• Incorporate art in the design process as a means • Select a composition of materials that are du- of interpreting the corridor’s theme rable for the projected life span of the project. • Integrate art as part of the functional aspect of • Avoid the use of ready-made, randomly placed, highway facilities stand-alone objects, or imprints that portray • Artists should coordinate with community little meaning. members, landscape architects, and architects • Use evocative artistic expressions that engage throughout the design process observers and complement highway structures • Scale artwork based on travel speed, slope and and the surrounding landscape. sight distance • Elements of highway art should not be obvi- ous or forced. Rather, transportation art should depict an excellence of craftsmanship, quality, 3.2 Create regionally appropriate and meaningful art. truthfulness, and originality. Art enhances the travel experience and can create (1) Transportation art should be as interesting when seen from a distance as it is in close proximity. the first impression of a place. Transportation art 3.4 Consider each art piece as part of a larger whole. should clearly express a meaning and purpose that Highway art can be carefully crafted, giving the relates to the surrounding locale, the unique cul- simplest of all elements a very powerful effect. ture and environment of the area, and the travel When planning transportation art, the entire experience. Patterns and objects used thoughtful- design segment and overall corridor should be ly, and even abstractly, can and should evoke a re- considered. sponse that connects travelers to the uniqueness of the site and/or the surrounding landscape. • Consider views to the surrounding landscape. • Art should to be scaled at a size relative to the • Patterns imprinted on a highway structure surrounding landscape and highway speed. should be designed as an artistic composition • Avoid distracting art pieces. Consider glance of objects, imprints, or patterns. recognition and the intensity of surrounding • Patterns should offer a level of complexity and features in order to prevent safety issues. interest appropriate to the place and highway travel speed. • Avoid the use of repetitive, overused symbols and patterns. • Consider artwork that utilizes light and shadow to create pattern and images. • Avoid monotony in the duplication of repeti- (2) Street elements can be designed as artful (3) Transportation art can be designed as a part of objects. all highway elements including bridges, walls, and tive literal pictorial application. drainage basins. 3.19 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

3.5 Ensure transportation art supports the Land- • Native American heritage scape Design Segment themes. • Mining Transportation art is not a typical project, and • Death Valley Historic Trail the choice of appropriate subject matter and • Mountain views media is essential to obtaining the desired ex- • Geology pression for each landscape design segment • Nevada Test Site theme. Choose art subjects that support the • Yucca Mountain landscape design segments’ themes, such as: • Desert National Wildlife Refuge • Humboldt-Toiyabe National Forest Mountain Desert Vista Enhance bridges, pedestrian structures, noise • Subtle gateway marking the arrival to Nevada walls, and retaining walls with appropriate mo- • Travel tifs and consider sculptural ornamentation, dec- • Mojave Desert landscape and wildlife features oration, and landmark features. • Outdoor recreation • Native American heritage 3.6 Engage local agencies and organizations in the • Mining planning process. • Mountain views Relationships with local agencies as well as • Geology the Nevada Arts Council should be developed to assist in the review and implementation of (1) Murals can be used in downtown environments to tell the cultural and natural history of a community. Destiny of the West proposed transportation art projects.

• Subtle gateway marking the arrival to Nevada • Consider transportation art at the onset of • Travel / tourism project development • Hoover Dam • For Community Matching Fund and Trans- • Outdoor recreation portation Art programs, refer to the guidelines outlined in the current Landscape • Lake Mead National Recreation Area and Aesthetics Community Match Proce- • Colorado River dures Manual: Guidelines, Applications, In- • Hydroelectric power structions and Forms for the Community Matching Funds and Transportation Art

Program, NDOT. Mojave Desert Vista

• Threshold/gateway; arrival to Las Vegas • Travel / tourism • Outdoor recreation • Mojave Desert landscape and wildlife (2) Decorative imprint motifs can be created with (3) Cultural symbols sandblasted into stone features a custom form liner and used to decorate walls. describe aspects of the historic emigrant traveler.

3.20 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

4.0 SIGNAGE 4.3 Create a family of iconic symbols to repre- • Information may include cultural and nat- • Utilize synchronous technologies that al- 4.1 Provide a standard, cohesive system of sent features. ural resources, tourist opportunities, and low users to control how and when they services along the corridor. access this additional information. service signage. Encourage the recognition of cultural and en- • Link the Audio Interpretation Program to • Incorporate the program into the Intelli- vironmental features through iconic imagery. NDOT manages the Tourist Oriented Di- the statewide Place Name Sign Program gent Transportation System regional in- rectional Signage System (TODS). TODS are and state welcome centers so that trav- formation architecture to allow messages preferred over numerous private individual • Signage should depict the general physi- elers can access specific information on to be updated in real time and be coordi- cal shape of the point of interest. selected sites. nated with AMBER alert and 511 traveler business signs and billboards. Work with lo- • Establish icons to represent general cat- information messages. cal community agencies and businesses to egories of interest within the Nevada develop and locate TODS. Refer to the Out- landscape. Illustration 1 shows examples door Advertising discussion (pages 1.14-1.15) of symbols to represent the categories. EXAMPLES AND CATEGORIES OF ICONIC SYMBOLS FOR PLACE NAME SIGNS for more information about billboards along Additional symbols should be developed to represent Nevada landmarks/historic the corridor. points, emigrant trails, and Native Ameri- can features. Engage Nevada tribes to 4.2 Implement a statewide Place Name Sign develop a universal symbol that is both appropriate and simple to represent the Program. state’s Native American resources. A comprehensive place name signage pro- • Features and points of interest to be gram should be implemented through part- recognized in this program will be coor- nership initiatives with local communities dinated with NDOT, State Parks, Native Mountains Rivers Sand Dunes and agencies. The program and sign types American tribes, and the State Historic RECREATION AREA: Preservation Office. SPIRIT MOUNTAIN COLORADO RIVER are described on page 1.10-1.11. Areas of in- SAND MOUNTAIN • Name and labels included shall be consis- terest within the design segments that could tent with State archives and map naming be highlighted include: conventions. Consider travel speed when names and labels are used. Lettering less • Historic features: Searchlight mining than 6 inches in height can be difficult to shaft, Boulder City historic district, Clark read at high speeds. County Heritage Museum, Boulder Dam • Final icon and name approval will rest with NDOT. Mining Historic Railroads Watchable Wildlife Hotel, Floyd Lamb State Park WATCHABLE • Wildlife and natural areas: Lake Mead Na- RAILROAD WILDLIFE tional Recreation Area, Desert National 4.4 Implement an Audio Interpretation Program. Wildlife Refuge, Mojave Desert, Cotton- wood Cove, Colorado River, Corn Creek, Develop and coordinate an audio/multime- Red Rock Canyon National Conservation dia interpretative program with the state- Area wide Place Name Sign Program. This program • Geographic features: Christmas Tree Pass, could be implemented via broadcast radio, Spirit Mountain, McCullough Mountain, CD or DVD programs, wireless Internet hot- Black Mountain, Black Canyon Historic Downtown Ghost Towns Hoover Dam spots, satellite transmission, or other media • Cultural/recreational resources: Fort Mo- BOULDER CITY that allows travelers to access additional in- GHOST TOWN HOOVER DAM jave Indian Reservation, Las Vegas Paiute (1) Universal symbols represent Nevada’s cultural and environmental features as part of the Place Name Sign Program. Indian Reservation, Lake Mead National formation from their car. Additional categories such as Nevada landmarks/historic points and Native American features should be developed to Recreation Area provide straightforward icons that symbolize the resources.

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• Coordinate with programs, organiza- 4.8 Simplify signage supports used on bypasses tions, agencies, and municipalities along and elevated bypasses. the corridor, and explore ways in which to expand the Audio Interpretation Program. • Use single arm monotube systems for freeway signage support where possible. • Minimize the number of trusses used in 4.5 Coordinate the statewide Place Name Sign order to reduce visual clutter. Program with the national Watchable Wild- life program and with other community driven programs. Work with other agencies, civic groups and municipalities to provide interpretive sig-

nage, where applicable. (9) As part of the anti-litter campaign, highway graphics and signage will be posted along the highway where trash accumulation is the most significant. 4.6 Highlight scenic byway entrances with signage that is coordinated with the statewide

Place Name Sign Program. (9) Single arm monotube with one signage board clarifies appearance of information. Reflect the place and character of the area with iconographic images incorporated on scenic byway signs.

4.7 Incorporate the anti-littering campaign. Anti-littering messages located at highway stops that include food and beverage services will provide an immediate reminder to (3), (4), (5) Examples of proposed anti-littering signage. travelers. (8) Sign bridge with numerous trusses is visually cluttered.

• Work with local vendors to place the anti- littering messages on disposable cups, plates, and other items likely to be tossed out the vehicle window. • Along non-interstate roadways, utilize pole signage anti-littering signs. • Develop signage that engages Nevada residents and encourages active partici- pation in maintaining clean and beautiful highways.

(7) Scenic Byways should include a specific pictorial graphic that is related to the place.

3.22 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

5.0 COLOR PALETTE APPLICATION 5.3 Use color composition on bridges to visually 5.1 Use a uniform, consistent color palette for all reinforce structural elements. highway structures. Use the base and accent colors to reinforce the Standard NDOT practice should utilize a uni- structural elements and integrity of a bridge. form and consistent color palette for all new and existing highway structures that comple- • Concrete bridge spans, super-structure support, and slope paving should be selected ments the surrounding landscape. Base and from the landscape segment base color. accent stain or paint colors for all highway • Railing and other features incorporating a structures along the Southern US 95 and US 93 material change should utilize accent col- Corridor have been selected. To ensure accu- ors. In addition, steel bridge spans should use an accent color. (1) The landscape inspires the color palette for (2),(3) Potential color palette choices were tested on site rate color reference, the colors are matched to each landscape design segment. Base colors along the corridor to identify colors that best complement the Dunn Edwards system, and are shown on correspond to the landscape design segment’s the landscape. environmental features. the right. 5.4 Blend new rock cuts and/or soil with the surrounding landscape. BASE COLORS ACCENT COLORS • Each highway structure should use a selec- Match new rock and soil treatments with ex- tion of one base color and up to two accent isting rock and soil color to blend disturbed ar- Mountain Desert Vista colors, chosen from the palette. No more #DE 6027 eas with the surrounding environment. than two different accent colors should be #DE 6074 used per site. #DE 6089 • Ensure roadway structures within a single • Use this process for any corridor project in landscape design segment use the same which rock cuts are included. base color and accent color(s). • Blend newly excavated soil and rock with Destiny of the West existing weathered rock. #DE 5325 • When existing structures require refinish- #DE 6047 ing, they should be stained or repainted • Where possible, the application should occur in a central location and away from sen- to be consistent with the selected color #DE 6013 palette. sitive receiving waters. • Specific town logos and transportation art Mojave Desert Vista are exempt (refer to Transportation Art #DE 5978 guideline, page 3.19). #DEC 717

5.2 Ensure accent colors highlight structural #DE 5914 aspects. Hoover Dam Structures Accent colors should highlight structural as- #DE 6214 #DEC 777 pects and/or details of highway structures, such as the beam of a bridge or a bridge railing. #DE 5537 • Ensure accent color application logically re- sponds to and reinforces structural features (4) The proposed color palette refers to the Dunn Edwards paint system. For reference purposes only. or change in materials.

3.23 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

6.0 ROADWAY DESIGN 6.3 Provide curbs no greater than six inches in 6.1 Reduce the appearance of a wide right-of-way height in downtown areas. through communities. Curbs define the edge of the highway and de- Every effort should be made to keep the road- lineate the pedestrian zones within commu- way as narrow as possible. Wide roads allow for nities. Curbs greater than six inches in height faster vehicular travel speeds, negatively im- may restrict pedestrian movement and create pacting the safety of pedestrians. difficult transitions at pedestrian crossings.

• Consider reducing the number of lanes. Four 6.4 Utilize on-street parking in community inter- lane highways may be retrofitted to two face zones to buffer the sidewalk from traffic. travel lanes or two travel lanes and a turn lane On-street parking accommodates access to local when other street systems are improved and overall traffic patterns move effectively. businesses and slows traffic.

• The appearance of a wide roadway may be reduced through the use of vertical elements, • Use curb extensions to enhance the visibil- curb extensions, and a narrow shy distance ity of pedestrians crossing the street (side clearance from fog line to edge of • Angled parking should only be used in areas structure). Utilize a one to two foot shy dis- of very low travel speeds. tance from curbs and medians in downtown • Provide a bike lane between parking and areas to reduce speed. travel lanes to create a buffer. (1) Street elements such as on-street parking, bollards, landscaping, and bulb-outs delineate distinct zones for • Provide passing lanes outside of rural com- • When bike lanes are not incorporated, con- automobiles and pedestrians and provide visual cues to slow down. munities rather than only within town to re- sider using a wider outside travel lane or duce the number of lanes within town and parking area to minimize conflicts with slow travel speeds. Highways that only pro- opening doors. vide passing lanes within communities en- • For all forms of on-street parking, maintain courage higher travel speeds through town adequate visibility and buffer zones between because it is the only opportunity to pass travel lanes and parking to prevent conflicts slower traffic. 10’ 10’ 5’ 12’ 12’ 12’ 5’ 10’ 10’ 10’ 19’ 12’ 12’ 12’ 19’ 10’ with through traffic.

6.2 Consider the use of rumble strips in transition 6.5 Integrate art, softscape, and hardscape as zones to signal a speed reduction. part of a simple landscape treatment for Changes in paving material and roughened pav- roundabouts. ing provide a visual and audible cue to drivers to slow down. • Landscape treatments within a roundabout should express the segment theme and • Rumble strips may be combined with en- community vision. hanced roadside treatments such as plant- • Sensitively site transportation art and ings and gateways to reinforce the entry plantings. into pedestrian areas. (2) Parallel parking can be incorporated in • Treatments should complement and coordi- (3) Angled parking can generate more parking • Avoid placing rumble strips in bike lanes, and relatively narrow right-of-way areas and spaces than parallel parking but requires more nate with the surrounding environment and helps delineate traffic and pedestrian zones. right-of-way distance and very low travel speeds. do not use in situations where bikes share landscape features and be part of an inte- travel lanes. grated design approach.

3.24 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

7.0 MEDIANS • Design medians to allow for adequate 7.1 Revegetate medians along rural high- percolation of water to avoid irrigation water infiltrating into the road base/sub- ways to integrate the highway with the base and causing pavement failure. landscape. Utilize native plant material to revegetate me- 7.3 Utilize medians to reduce potential vehicle- dians along rural highways to create a more pedestrian conflicts and to enhance pedes- natural and consistent visual experience. trian walkability.

Medians function to improve pedestrian 7.2 Utilize median plantings and treatments to visibility by minimizing turning conflicts enhance a community’s image. and directing and separating traffic. They Landscaped medians beautify wide streets provide an effective way of reducing con- by breaking up large expanses of pave- flicts between pedestrians and vehicles be- ment and making the street feel narrower. cause they allow pedestrians to incremen- Medians can include a combination of rock tally cross the traffic lanes. mulch, signage, plantings, and boulders that help to identify the character of the place. • Medians may be constructed with curbs and combined with pedestrian refuge • Avoid using asphalt paving in medians. islands. Stamped, colored concrete or pavers should be used in narrow medians (less • Future development, access manage- than five feet wide). Paving score pat- ment, usage patterns, and changing terns should be simple and coordinate transportation demands should be ex- with surrounding architecture and pe- amined when determining if raised destrian areas. Colored concrete should medians are the appropriate solution for be the segment’s base color (see Color the roadway. Palette guidelines, page 3.23), or coordinate with adjacent pedestrian walkways. 7.4 Direct stormwater to planted medians and • The placement of plantings and treat- landscaped planting strips where feasible. ments should direct pedestrians and facilitate the vehicle operator’s view. Utilize drainage swales within medians to Selected plant species should also handle excess stormwater runoff . be suitable for the harsh roadway environment. • Carefully design curbs, gutters, catch • Planted medians are generally the width basins, and drain grates for ease of of the center turn lane but can be as nar- maintenance. row as five feet. Regardless of width, me- • Ensure pedestrian movement is not un- dians need to be designed to allow for duly impacted by ponding water. safe maintenance as well as for antici- pated plant growth. • In areas where run-off may contain high levels of salt, select salt-tolerant plants. (1), (2) Medians should be designed to accommodate stormwater runoff where possible and be planted with low maintenance, drought-resistant plant materials.

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8.0 PEDESTRIAN CROSSINGS • Curb extensions should extend into the 8.1 Improve pedestrian safety at crossings. street no further than the edge of the travel or bike lane. They can be used at mid-block Motorists can see striped crosswalks from a crossings and are beneficial when combined greater distance. with pedestrian refuges. • Refuge islands are located at crosswalks in • Utilize a zebra striping pattern for painted the middle of streets to provide a safe wait- crosswalks (see illus. 1). ing area for pedestrians. • Crosswalk striping should correspond to • The waiting area in refuge islands should be the width and location of sidewalks. in line with the crosswalk and as wide as the crosswalk to allow persons with disabilities to cross without obstruction. 8.2 Use alternative paving type, coloring, or other • Refuge islands may include additional means to visually highlight pavement in pe- pedestrian safety features, such as bol- (1) Pedestrian crossings should be visually highlighted (2) Refuge islands provide a safe place for pedestrians destrian crossings. lards and flashing signs, to enhance their with zebra striping or changes in paving type. to wait while crossing high traffic areas. Crosswalks may be marked with distinctive visibility. paving material, colors, and texture. 8.4 Alert motorists to pedestrian crossings • Concrete is preferred over brick for its dura- through the use of signage and flashers. bility. Concrete may be stained, embossed Pedestrian signals work in conjunction with with patterns, or constructed with unit traffic signals to assign right-of-way at inter- pavers to give crossings a distinctive feel in particular areas. sections. • Textures and materials should provide a visual contrast with the adjacent road surface, • Active signals are preferred over passive however, they must also provide a smooth signals. travel surface and good traction. • Pedestrian signals are appropriate at all intersections with traffic signals where cross- (3) Contrasts in paving color and texture indicate to (4) Crossings with focal paving patterns provide detail ing is permitted. 8.3 Reduce curb-to-curb distances at crosswalks. motorists that they are approaching a pedestrian that is visually appealing to pedestrians and signifies crossing. that the road was created with their safety in mind. Incorporate curb extensions as part of the highway system when on-street parking is 8.5 Provide appropriate lighting to enhance vis- provided. Provide refuge islands to break up ibility of pedestrians by motorists. long crosswalks. Pedestrian-scale lighting and motor vehicle- Curb extensions reduce the crossing distance scale lighting should complement each other for pedestrians, increase visibility for motor- in an effort to ensure that both pedestrian ists and pedestrians, prevent illegal parking at crossing areas and travel lanes are effectively corners, and provide additional room for peo- illuminated. ple waiting to cross the street. • Accentuated lighting may be used at crossing points to further distinguish crossing locations.

3.26 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

8.6 Consider pedestrian facilities as part of roundabout design. Pedestrian crossings at roundabouts should balance pedestrian convenience, pedestrian safety, and roundabout operations.

• Crossings at roundabouts implement the same design strategies identified for typical crosswalks but also need to consider the unique geometry of the roundabout design. (1) Consider the use of curb extensions in highly utilized (2) Streetscape elements help define pedestrian (3) Pedestrian crossings at roundabouts require additional pedestrian areas in order to provide pedestrian amenities gathering places and safe crossing zones. identification through striping and paving changes due to 8.7 Balance the need for adequate vehicular turn- and reduced crossing distances. the unique geometry of these intersections. ing radii with pedestrian needs. A tighter turn or shorter radius forces drivers to slow down, allowing them to see pedestrians and make quick stops. Addition- ally, they create more sidewalk space for pedestrian amenities.

• Reduce corner radii where feasible to shorten and align pedestrian crossings while reducing vehicle turning speed. • Reduce the use of slip lanes (channeliza- tion) where possible to minimize pedestrian/vehicular conflicts. (4) Pedestrian movement is directly affected by turning radii. (5) Tighter, shorter turning radii reduce traffic speed Larger radii increase traffic speed and crossing distance for and shorten pedestrian crossing distances. Motorists are pedestrians, thereby reducing pedestrian comfort. better able to see pedestrians and make quick stops.

(6) Breaks in the median provide a safe haven and allow pedestrians to cross lanes incrementally. Pedestrian refuge islands provide an additional level of security while crossing. 3.27 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

9.0 NON-MOTORIZED TRANSPORTATION • Ensure that direct connections are made SYSTEMS (NMT) to existing and future trail systems and shared-use pathways. 9.1 Consider aesthetics as part of bicycle facility design. 9.4 Incorporate designated bike lanes within the Users of non-motorized transportation sys- roadway to link regional bike trail systems. tems are more likely to use facilities that in- Within developed community areas, bike clude aesthetic treatments and that link to lanes provide access to regional bike trail critical destinations. systems and to local community facilities. • Minimize underpass length to allow for natural lighting. • Stripe, sign, and provide a painted bike lane symbol for designated bike lanes to • Utilize transportation art consistent with promote driver awareness, better define the segment theme. travel lanes, and enhance user comfort. (1) Regional multi-modal trail systems should be integrated into the highway right-of-way wherever possible. • Enhanced paving or pavement markings 9.2 Engage agencies and organizations in the may be used in downtown areas. planning and design process. • In areas of limited right-of-way and low Ensure proper planning conveniently ac- speeds, bicyclists may share travel lanes in order to accommodate street improve- commodates NMT while minimizing ad- ments such as widened sidewalks and verse safety and environmental impacts. on-street parking. However, bike lanes should be included as part of the roadway • Engage Federal, State and local agencies whenever possible. as well as local user groups and organizations in the planning, design, and imple- 9.5 Consider bicycle facilities as part of round- mentation of non-motorized transportation facilities. about design. • Ensure the maintenance of connections to regional trails and pedestrian systems. • Consult the statewide bicycle and pedestrian plans prepared by NDOT. • Provide signage to trail heads and regional trails to encourage NMT use.

(2) Native materials should be used for all trail system 9.3 Integrate NMT into the right-of-way. hardscape and softscape treatments. Where topography, site conditions, and land use warrant, separate bicycle paths may be built in the right-of-way.

3.28 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

10.0 BRIDGES • When bridge supports involve stream cross- • Ensure mulch materials match bridge struc- 10.1 Use a consistent bridge design. ings, a column shape must account for ture color and the surrounding landscape bridge scour. (see Color Palette guideline for appropriate Bridges are prominent features in the land- color selection, page 3.23). scape and can significantly affect the visual 10.3 Use visually transparent bridge rail structures. • Use rock mulches, stone rip-rap, or deco- quality of the environment. NDOT standard rative slope paving (minimally) to stabilize Consider open rail design of steel rail or con- bridge design incorporates a concrete and abutments below the bridge. crete barrier and steel, both to create a more steel I-girder, or concrete and steel box girder • When slope pavement is used, include integral refined bridge with a lighter appearing span, color or stain to match base color palette. bridge structure of similar proportion, finish, and to maintain scenic views and views to the and barrier rail design. The major structural el- surrounding landscape. ements – piers, girders, and abutments – also serve as the major architectural features. • Use shadow lines and patterns to avoid blank surfaces where safety mandates a solid con- (1) Integrate simple bridge design into the • Aesthetic qualities must consider propor- crete barrier. embankment and add landscape planting. tion, rhythm, balance, and unity. Refer to the Aesthetic Guidelines for Bridge Design (Minnesota Department of Transportation) 10.4 Consider fill embankments and approach rails for a complete discussion. as part of the bridge design. • Bridge form should be simple and All NDOT bridge design should consider fill uncomplicated. embankments and approach rails in concert • Large amounts of slope paving should be with the abutment, bridge barrier rail, and avoided. (2) Consider bridges with retaining wall abutments (3) Consider using a battered abutment. superstructure. and 3:1 slopes. • Street names should be embossed on the bridge span, providing place identification for the motorist. • Materials, height, and attachment details • Where special conditions arise and larger or should be carefully considered when con- different bridge spans or types are required, necting guardrails to the bridge to avoid ensure landscape and aesthetic aspects are joining incompatible materials and creat- incorporated into the standard design type. ing abrupt vertical changes at connection points. • Avoid slope paving at bridge embankments,. (4) Avoid weak proportions in bridges with shallow 10.2 Use simple sub-structure and support features. (5) Avoid characteristic shapes that do not allow Grade to a slope of 3H:1V to allow for slope or undersized abutments. the structure to be visually supported. Use simple sub-structure and support features revegetation. with strong proportional relationships in all standard bridge design. 10.5 Use landscape or rock mulch to stabilize embankments. • Avoid “V”, “Y” or flared support shapes in Contour grade embankments and use landscape sub-structure and support features. planting to maintain embankment. Use rock re- • Use simple geometric shapes to minimize taining walls to establish suitable flat landscape the support profile as well as the number of supports required. areas where right-of-way is narrow. (6) Avoid 2:1 slopes as the primary bridge abutment (7) Consider simple geometric shapes to minimize and the need for slope pavement. the profile of bridge supports.

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10.6 Select vandalism-resistant finishes. illus. 7). Street name identification should be Approach Transition Slope Bridge Substructure Bridge Bridge span Bridge Embankment Finish type, color, and surface patterns are placed on the concrete barrier rail. barrier barrier rail paving is barrier rail is poorly span is proportion abutment fill slope is rail height and required lacks visual integrated glaring is bulky the largest important design elements in coordinating connection because relief into the white feature of the is poorly of exces- bridge span bridge the structure with the surrounding land- 10.9 Accentuate locations where bridges cross ma- attached sively steep scape. Select bridge finishes of appropriate jor water bodies, drainage courses, or canyons. embankment color (see Color Palette guideline, page 3.23) Utilize landscape treatments in order to and vandal-resistance. highlight crossings and connect motorists to the landscape. • Where appropriate, structures with detailed treatments located in urban areas • Consider the integration of a grade-sepa- Steep slopes prevent planting should be treated with non-sacrificial rated pedestrian crossing into structure and are prone to erosion anti-graffiti finish. when possible. • Color and finish selections will assist in re- • Coordinate with local jurisdictions to de- (1) Avoid components and proportions lacking visual appeal. inforcing the design intent of the bridge termine the need for these features. structure. Approach Bridge Erosion Bridge Substructure Superstructure Bridge Embankment barrier rail barrier control span proportion with simple with horizontal abutment fill slope 10.10 Retrofit existing bridges. rail is light and open columns shadow lines designed flattened to 10.7 Create a visual design unity among all exist- as strong allow planting Bridges are gateway features to cities and visual and reduce ing and new structures. communities. anchor erosion Ensure bridges coordinate with noise walls, retaining walls, and other highway struc- • Aesthetic treatments, such as staining, tures. should be the basic treatment for updat- ing existing structures. • Establish a visual design relationship that • Where possible, include segment-appro- coordinates materials, patterns, color, and priate artistic motifs with sculptural orna- other design elements of structures. mentation and decorations. • Establish a visual design continuity be- (2) Consider the recommended landscape and aesthetic treatments and guidelines to improve the appearance of bridges. tween existing bridges and other struc- 10.11 Provide direct connections from bypasses tures by implementing a paint/stain retro- Accent color Base color Rail termination fit program to unify color schemes where back to the community core. they vary within a corridor. Heightened levels of landscape and aesthetic treatments, including effective signage, Wall with horizontal shadow lines and smooth 10.8 Design bridges to accommodate additional should mark exits to downtown areas. finish makes up 1/5 of the wall abutment. elements and structures that are required. Random vertical pattern wall finish

Accommodate pedestrian corridors and oth- • Increasing density of landscape and archi- Light and thin proportion for span tectural elements heightens the sense of 3H:1V embankment slope, no slope pavement additional structures with extra width. er arrival into community centers. In areas where noise walls are required on Vertical abutment structure should be six feet high. bridges, the bridge should be widened to allow for noise walls that are completely sepa- (3) A combination of preferred bridge design elements will result in a more visually attractive structure. rated from concrete barriers (refer to Noise Reduction and Walls guideline 11.5, page 3.33, 3.30 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

(1) Avoid bridge structure design that creates walls parallel to the (2) Bridge design can integrate retaining travel lane. Utilize graded slope and abutments. walls and terraces to minimize steep slopes and create areas for landscape planting.

(3) Symmetry and correct proportions significantly enhance the visual appeal of structures. The bridge color selection emulates the natural colors of (4) Special bridge design elements such as native stone, color the landscape so as not to distract from the view of the horizon. treatments, and cable systems can be used to create a focal feature.

3.31 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

11.0 NOISE REDUCTION AND WALLS • Maintain consistent use of the selected ma- 11.1 Consider grading to minimize wall height. terial, pattern, color, and texture. The required prototypical surface pattern is shown Where possible, use an embankment slope with in illustration 5. landscape planting to buffer sound, or use a • Avoid using multiple materials, such as steel combination of earth forms and noise walls to and concrete or CMU, on continuous spans achieve structural integrity and buffer sound of wall. while limiting actual wall height. • Post and panel systems are not encouraged for noise wall construction, and should be used only for temporary applications. If a • This guideline does not change or supersede post and panel system is used, it should be federal noise wall requirements, which speci- constructed with a single material, prefer- fy the location of noise walls according to ad- (1) Rusticated variable vertical patterning (2) Retaining and noise walls should be ably pre-cast concrete for all components. adds visual interest. separated from concrete barriers and other jacent land uses and a sound level threshold structures to allow space for landscape approaching 67 decibels. • Use visual design themes and/or pictorial motifs comprised of simple patterns and surface planting. • Noise walls should not be greater than 14 feet texture, and carefully design the motifs com- in height without a step in the wall plane. position (height and position) on the wall. • Walls used only for visual screening may not • Noise walls over 12 feet in height require be taller than ten feet. special graphic or pattern treatment (refer to • Use natural barriers and earth forming when Transportation Art guideline, page 3.19, for possible. more information about appropriate subject matter). 11.2 Provide landscape planting and setback space between the vehicle recovery zone and the 11.4 Create visual breaks and interruptions to avoid noise wall. monotony along noise walls. (3) Form liners can be used to produce (4) Form-lined concrete and decorative railings details in wall patterns. can be used to create a desert visual design When necessary, work with developers to en- Use staggered and/or curved walls of varying theme. sure adequate right-of-way is provided for lengths to provide visual interest along extend- sound abatement. ed stretches of noise wall.

• Consider grading to minimize wall height. • Avoid abruptly ending noise walls. Use a wall Landscape plantings in front of walls will return of three feet for noise walls located soften the appearance of large wall facades. outside of the clear zone. • Ensure planting and maintenance is provided. • Battered walls, also known as inclined walls, can provide additional interest. • Shadow patterns can be introduced to create 11.3 Select a simple design palette. visual interest that shift and change through- Choose a simple design palette of material, pat- out the day. (6) Landform and plant materials can be used to buffer road noise from adjacent land uses. tern, color, and texture that coordinates with the • Use appropriate ornamentation to break up corridor’s landscape design segment theme for the surface of long, uninterrupted spans. (5) The required prototypical surface retaining walls and noise walls. pattern is rusticated variable vertical ribbing. Dimensions vary between two to eight inches apart.

3.32 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

11.5 Separate noise walls from other highway Individual step height structures and set back from travel lanes. not to exceed three feet. Ensure noise walls are carefully planned for 20 - 30 ‘ and integrated with the design of the highway and/or bridge. (1) Consider - Tapered Transition: Allowed transition for noise (2) Consider - Curved: Allowed transition for top of noise wall. wall grade changes of less than three feet. • Avoid attaching noise walls to concrete barriers, bridges, and/or retaining structures. When noise walls are attached to Individual step height such structures, use compatible materials, not to exceed two feet. colors and forms. • Recess noise walls a minimum of 30 feet from edge of travel lane where possible. Noise walls may be placed on top of concrete barriers only when no other practi- (3) Consider - Stepped transition: Allowed transition for noise (4) Consider - Stepped transition with staggered walls: cal solution exists. wall grade changes between eight inches and two feet. Preferred transition for noise wall grade changes. Provide a minimum stagger of 24 inches between wall planes. • Consider drainage impacts when locating or placing walls as areas flanked by walls will need to freely drain.

11.6 Encourage noise-compatible land uses adjacent to highway corridors. At the planning level, encourage land uses (5) Avoid - Angular wall top: Not allowed for top of noise walls. (6) Avoid - Eased transition: Not allowed for top of noise walls. that are compatible with highway noise, such

as commercial and light industrial areas. Maintenance Access Patterning and shadow lines are required on both sides of noise wall and concrete barrier • Noise sensitive facilities (schools, churches, etc.) require sound abatement strategies. • Coordination at the planning stages is critical to avoid conflicts.

11.7 Retrofit noise walls that do not meet recommended requirements.

• Painting should be the basic treatment to improve existing structures. Drain • Enhancements could include the application of artistic motifs with sculptural (7) Walls approaching bridges can be adapted with a setback (8) When concrete barrier and noise walls co-exist ornamentation and decorations, or vi- and planting strip. A flare of the upper one-quarter of the wall without buffer space, wall is integrated into concrete barrier rail. relief by modulating the top edge further prevents an enclosed, narrow passage. Design flared sual walls so they do not become top-heavy and cause hazards to of walls. pedestrians and motorists. 3.33 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

(1) Avoid small scale joints, octagon, or cruciform shaped panels. These are only acceptable when textured with a rusticated variable vertical pattern.

(4) Turning the ends of retaining walls (5) A minimum wall return of three anchors them into the earth and creates a feet is required for noise walls at the finished end to the retaining wall. beginning of the wall facing the driver.

(2) Avoid using multiple materials, shapes, and joint patterns.

(3) Consider the preferred rusticated variable vertical texture and pattern. Surfaces should have a single finish whether MSE, cast-in-place, or other wall type is used. Consistency with other structures is required. (6) Retained slopes with walls should return to meet uphill grade.

12.0 CONCRETE BARRIERS AND 12.2 Avoid bright and shiny guardrails. GUARDRAILS Use acid-washed steel guardrails where ap- 12.1 Stain concrete barriers to blend the roadway propriate. into the surrounding environment.

• Concrete barriers should be stained to match the segment’s base color. Refer to Color Palette guideline, page 3.23, for more (1) Acid-washed steel guardrail blends into information on color selection. the surrounding landscape better than shiny galvanized steel.

3.34 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

13.0 LIGHTING • Use poles and fixtures with consistent 13.1 Avoid over-lighting. maintenance requirements and procedures for lighting types used within the same Excessive high mast lighting can create light maintenance district. pollution along a corridor and impact views to • Use accent color palette for poles (refer to the surrounding landscape. Color Palette guideline, page 3.23, for more information). • Study current lighting level standards to • Select a sleek and simple pole configuration. determine levels needed for safety only. • Allow for context-sensitive design in fix- Adjust current standards, if necessary, and tures and poles where appropriate, particu- (1) Lights can be incorporated in the bridge design as a feature apply the minimum height, illumination, larly in areas such as historic sites. of the approach. and number of light masts required. • Consider color properties when selecting • Focus attention on luminance versus illu- lamps. Metal halide lamps are preferred in mination (i.e. brightness of pavement ver- pedestrian areas. Mercury vapor lamps pro- sus brightness of light). duce favorable lighting for enhanced land- • Along all sections of the corridor, use light- scape treatments. Energy efficient high- ing fixtures that minimize light pollution pressure sodium lamps are commonly used and provide even light dispersion. for large portions of the roadway. • Eliminate lighting where possible. • Use cobra head or shoebox-type pole and 13.3 Lighting height and brightness should be con- fixtures instead of high mast lighting sistent with pedestrian scale needs in down- where appropriate. (2) Limit use of high (3) Avoid this type of (4) Consider these preferred fixture and (5) Powder coat coloring town or heavily pedestrian-oriented areas. mast lighting. pole design in favor pole configurations. helps blend poles into the Create desirable pedestrian environments by of more streamlined surrounding environment. attachments. 13.2 Use a consistent lighting fixture and pole. using pedestrian-scale lighting along sidewalks. In central commercial districts and town centers, use light fixtures and lamps that are con- • Fixtures should be more closely spaced than sistent with surrounding architectural styles. conventional “cobra head” street lights. • Lighting height and brightness should • Use a durable, powder-coated finish for light clearly illuminate walking paths. poles of a color that matches other structures and the surrounding landscape. Typi- cally use colors that blend with the background and do not visually overwhelm.

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14.0 FENCING • Minimize the use of fencing within rights- 14.1 Ensure right-of-way fencing blends with the of-way where possible. landscape. • In urban areas, use colored steel fencing such as powder-coated, acid-washed, or Fencing can be used in non-urban areas to de- stained-galvanized fencing that visually re- lineate the highway right-of-way and control cedes into the urban background. access.

• Use wire fencing that blends with the landscape and conforms to current Nevada Re- vised Statutes. • Ensure right-of-way fencing is well maintained. (1) Three-strand fencing maintains the rustic character of the rural segments of the corridor and minimizes the visual impact of fencing on the driver.

15.0 GRADING AND RETAINING WALLS • Carefully grade slopes around natural 15.4 Utilize retaining walls that reflect sur- 15.1 Avoid creating steep slopes. outcrops and abrupt topography to im- rounding landform and soil colors to mini- prove aesthetics and allow for easier and mize large slope cuts. Smooth, moderately inclined slopes will more cost-effective maintenance. Staggering, terracing, and progressive off- blend more readily with the surrounding • Topographic patterns should be consid- landscape, are safer to maintain, and are ered with proposed grading. Valleys, high set of retaining walls can stabilize slopes less vulnerable to erosion. points, and ridges require graded transi- and reduce erosion while blending more tions rather than abrupt embankment smoothly into surrounding landforms than cuts or fills. • Flattened fill slopes can assist in decreas- terraced high wall cuts. ing erosion. Flattened slopes also reduce • At a minimum, ensure that all construct- (1) Rounded slopes help smooth the transition between cut and the need for guardrails and provide bet- ed slopes are revegetated (refer to Na- • Select retaining structures or slope sta- fill slopes and existing topography. ter accident recovery in the roadside tive Plant Revegetation Softscape Type bilization methods that blend with the clear zone. guideline, page 3.44). surrounding landscape and encourage Rounded slope condition should be 1/6 of total slope • Acquire adequate right-of-way to pro- revegetation. Replace “V” swale with rounded vide enough land to construct the de- 15.3 Create artful earthwork. swale profile that transitions to • Provide landscape plantings in front of sired slope and grade. the embankment. Create landforms that respond to the unique- walls to soften their appearance. • In some locations, steeper slopes may be ness of the site, the surrounding landscape, • Provide a minimum of eight feet be- unavoidable to protect important natu- tween terraces to provide for landscape ral or cultural resources adjacent to the and the roadway travel experience. Use a rounded slope planting. highway. condition at top and bottom of slope • Contour grade to create effective plant- • Carefully design gabion walls. Color ing embankments, shadow patterns, and should be dark and muted to match soil 15.2 Create smooth landform transitions and re- artful earthwork. and surrounding landscape. Wire mesh should match stone color. Plant terraces vegetate slopes. • Where feasible, grade slopes to provide with native vegetation to break up visual for water harvesting (reclaimed surface (2) Smooth transitions between cut and fill slopes and existing impacts. • Use finish-grading techniques, such as runoff). conditions can be accomplished by rounding the slopes. slope rounding at the top and bottom of • Retaining walls should be consistent cuts, to create smooth landform transi- within a segment and utilize a simple tions that blend with the natural terrain. design palette and anchor to the earth.

3.36 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

• Utilize a simple design palette. Avoid using multiple materials such as steel, concrete, keystone block, or CMU on walls. Exterior finish for retaining walls should have the same visual appearance independent of the type of wall. • For MSE walls, rectangular-shaped panels with vertical joints in a consistent pattern are preferred. All panels should have a rusticated variable vertical pattern that extends across the entire surface. (1) Consider a step or change of plane for retaining walls (2) Avoid the tunnel effect created by retaining walls greater greater than 14 vertical feet. than 14 vertical feet.

(3) When gabion walls are necessary, ensure that the wire and stone colors complement one another and the surrounding landscape.

16.0 ROCK CUT AND EXCAVATION • Blend rock cuts to match natural rock 16.1 Analyze rock geology. forms and use naturalized bedding planes to avoid creating an unnatural rock face. Provide a multi-disciplinary team of civil en- • Ensure all designed landforms are natural gineers, geotechnical engineers, and land- in appearance and blend with the topog- scape architects to ensure that the inherent raphy and geology of the surrounding character of a rock’s natural bedding planes, landscape. fractures, joints, and overall stability is care- • Match new rock and soil excavations with existing rock and soil using rock staining, fully analyzed and informs the design of all soil-coloring treatments, and/or acceler- rock cuts. ated weathering techniques. • Where site conditions and cost analysis • Conduct careful rock geology, site, and permit, acquire adequate right-of-way to (1) Rock cuts and excavation should be natural in form, shape, and cost analyses, and design rock cuts that provide enough land to design and build texture. Rock formations, such as this rhyolite outcrop, have an avoid the need for rock fall protection the desired rock cut slope and grade. inherent visual form that can be duplicated in custom rock excavations. fencing.

16.2 Design rock cuts to be natural in form, texture, and color in relationship to the surrounding landforms.

(2) Re-sculpted rock cuts change artificial slope banks into naturally occurring landforms. Plan cuts that terrace, bench, and use bedding planes found in existing rock formations. 3.37 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

17.0 DRAINAGE 17.2 Revegetate drainage infrastructure. 17.1 Use naturalized channel design and infiltration Drainage detention and infiltration areas methods. should be shaped with natural undulating edg- Avoid paving drainage ditches or check dams es and bottoms rather than angular embank- with asphalt or concrete. Where possible, se- ment slopes . cure check dams with rock and use naturalized channel design and infiltration methods to en- • Upper slopes of drainage detention basins should be revegetated or covered with ap- hance, both functionally and visually, highway propriate ground treatment (refer to Ground drainage systems. Treatment softscape type guideline and Native Plant Revegetation softscape type guideline, • In unique situations, utilize geotextiles, im- page 3.41). pervious mats, or stone lining to maintain the appearance of a natural channel. 17.3 Naturalize culvert ends. (1), (2) Rock bed drainage reduces erosion, allows some water to infiltrate, and can provide • Excessive flow velocities and erosion poten- irrigation for adjacent plant materials. tial may demand paved drainage surfaces. • Use rock to naturalize inlets and outlets. Consider the use of open cell concrete block with native grass or rock mulch that bhlends • Culverts should not be exposed except at with the surrounding soil. the end of headwalls and endwalls or with mitered end sections. • Vary the size of rock treatments. Meander naturalized treatments so that they feather • When it is essential to have portions exposed, into the landscape. they should be stained to blend with the surroundings. • Consider whether trails or wildlife passages can be coordinated with culverts. (3) Designing detention basins and stormwater uses with naturalized, curvilinear shapes is preferred over the use of “V” shaped channels.

18.0 EROSION CONTROL • Permanent revegetation efforts can be 18.1 Stabilize soils to ensure successful reveg- improved by providing in situ topsoil, native vegetation fragments, and rocks and etation and to control erosion. Use native improving soil salvage techniques and materials for stabilization and revegeta- seed mixes. tion, to blend with surrounding landscape. • Provide uncompacted topsoil surfaces prior to seeding (approximately 85% • Use techniques such as heavy textured compaction). (1), (2) Application of geo-textile fabrics aid in erosion (3) Application of soil stabilizer aids soil and/or gravel mulches to slow water control. in dust and erosion control. run-off and provide dust control. 18.2 Refer to temporary and permanent erosion • Where water concentrates, riprap mate- control best management practices as pre- rial and/or geotextile reinforcement may pared and documented by NDOT. be used to avoid erosion.

(4) Fiber rolls reduce sediment migrations. 3.38 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

19.0 WATER HARVESTING depressions increases water retention provide increased water to the planted 19.1 Maintain soil moisture and improve water and provides moisture to the plants. areas. Within interchanges, planted ar- Rocks create impervious cover, resulting eas should be sited where roadway run- retention by preserving topsoil, site sur- in water harvesting for the remaining off can be directed to provide water to facing, site grading, track walking, apply- soil and seeds. Rocks also create a rough, these areas before it enters structured ing mulches and tackifiers, sensitively sit- uneven surface, thereby slowing water drainage systems. This method enhances runoff, allowing water to collect and in- plant growth, and supplements the irri- ing features, and using permeable paving creasing infiltration. Rock mulches retain gation needed for high water use plants, or cisterns. moisture and protect plants by reducing thereby reducing the cost of irrigation. The collection of runoff for use in land- evaporation, providing wind protection, Features used to direct or store water scape design is especially important in arid and moderating the soil temperature so can be part of the aesthetics of design. that it is cool in the summer and warm in climates. Increase the availability of natural the winter, effectively lengthening the • Permeable pavements: Pavements such as water by directing runoff and precipitation growing period. flagstone or permeable asphalt should be into areas such as planting beds prior to used where appropriate to aid in the infil- (1) Water basins should utilize natural materials and be used as a water source for adjacent landscape areas. moving it off site into drainage structures. • Site grading: Grade surfaces to slow tration of precipitation in urban areas. Water harvesting methods also reduce the water flow, encouraging absorption. In- stead of a continuously angled slope, po- amount of runoff, thereby reducing non- • Water storage in cisterns or tanks: In sition breaks or depressed areas around some cases it may be desirable to store point source pollution, erosion, and flood- planted areas. Contour slopes so that water in a cistern for later use. Storage ing while recharging the groundwater. water slows and infiltrates around veg- provides the most control and flexibil- etation. Prevent erosion by minimizing Soil moisture and water retention can be in the use of harvested water. Cis- slope angle and directing water flow. ity maintained and enhanced in several ways, terns collect water throughout the year including: and store it until it is needed during the • Track walking: Where possible, track height of summer. Consider the need for walk all slope surfaces to stabilize ma- mosquito abatement during design. Wa- • Topsoil preservation: Stripping and sal- terial and minimize potential erosion. ter should not be stored in open systems vaging the existing topsoil, vegetation Track walking should be performed per- for long periods of time. Cisterns can be seeds, and plant fragments for later re- pendicular to the contours. sculptural and incorporated into an aes- application should occur at every site thetic design, or they can be large but requiring disturbance. This live topsoil relatively flat, and located under a park- and tackifiers: Use mulch and contains organisms, seeds, and plant • Mulches ing lot. fragments that increase the potential tackifiers to hold seed and topsoil cover success of revegetation and increases and assist with moisture retention dur- both the quantity of organic matter and ing germination. Mulches such as bark or 19.2 Use natural and/or artificial products to col- permeability of the soil. straw can be used to stabilize seeds and lect, store, and release water for plant use. topsoil and assist in moisture retention during plant germination and growth. Use products such as: • Site surfacing: Rock surface composition should simulate the original or adjacent • Pumice wicks surface cover or be integrated as part of • Siting of features and facilities: Thought- the overall design. Create artful water ful consideration should be given to the • Polymer products harvesting features that contribute to siting of features and facilities. Rest area • Diatomaceous earth the aesthetic quality as well as function- and other facilities where vegetation is • Wattles ality of landscape treatments. Placing desired should be located where natu- rocks and shaping landforms to create ral surrounding upland topography can

3.39 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

20.0 IRRIGATION • Temporary watering is required for contain- 20.1 Select efficient and effective irrigation systems. erized native plants for a period of approximately one to two years, depending on the Select efficient and easily maintained drip irriga- success rate of revegetation. tion systems that have a central controller. • Permanent irrigation to individual plants is required for all enhanced native, regionally • Consider the use of reclaimed water, adapted, and regional ornamental softscape including fully treated effluent and water types. harvesting techniques, as a supplement to • When a water source is not available, con- irrigation. sider water harvesting methods or the use of • If a non-domestic water source is used, in- vertical elements and structures. clude a filter system to prevent clogging of emitters. 20.3 Manage the high concentration of salts. • Consider threaded emitters as opposed to Nevada’s desert soils often concentrate salts (1) Drip irrigation is required for all enhanced native, regionally punch-in types to minimize vandalism. adapted, and regional ornamental softscape types even after at the outer edge of the wetted soil volume, they have reached maturity. including near the soil surface, particularly in 20.2 Provide appropriate irrigation for each drip irrigation situations. softscape type. The early stage of revegetation growth de- • Salt management techniques include flush- mands the most water use and is most critical ing the soil periodically with heavy watering to the establishment of young plants in an arid and/or planting salt tolerant materials. climate. As revegetation becomes more established and mature, the demand for water will (2) Certain plant species such as Ephedra and Rabbitbrush are lessen to the point of complete removal. adapted to survival in saline soils.

21.0 SOFTSCAPE TYPES AND TREATMENTS 21.3 Preserve healthy trees and vegetation. GENERAL GUIDELINES Mature vegetation is an integral part of com- 21.1 Consider aesthetics and maintenance of se- munity identity and an important public re- lected softscape treatment. source that enhances the quality of life. Previ- In all non-paved areas, select ground treat- ously landscaped areas with ornamental plant ments that meet both aesthetic and mainte- materials that are in good condition, form, and nance requirements. health shall be preserved. All softscape treatment projects shall include a tree inventory 21.2 Select appropriate plant sizes. listing all protected trees and other landscape The minimum plant size used should consider materials within the right-of-way. The plan plant survival and the visual effect of the material. should include a listing of species, size and condition of each tree, index of trees to re- • Consider sunlight, water requirements, and move or preserve, and specifications for tree wind exposure when placing plant material. maintenance during construction.

3.40 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

GROUND TREATMENT SOFTSCAPE TREATMENT 21.6 Coordinate ground treatment with sur- 21.5 Implement appropriate ground treatment rounding landscape. and softscape types. Ground treatment should coordinate in Use recommended ground treatment and size, texture, color, and aggregate mix with softscape types to assist with erosion the surrounding landscape. and dust control, consistent with NDOT specifications. • Mulches composed of multi-sized rock that resemble natural patterns of sur- • Rock mulch, where used, should comple- rounding soils should be considered as a ment and/or match the surrounding nat- matching technique. ural environment. • Distribute scattered rock mulch in a • For rural areas, ground treatment should pattern similar to that found in the sur- be derived from natural patterns found in rounding landscape instead of a thick, even spread of rock mulch. playas, foothills, or ephemeral drainages. (1) A mix of aggregate size and color helps re-establish (2) Visual interest is enhanced by using stone ground • For landscaped areas in urban settings, disturbed slopes to a naturalized condition. cover of various sizes and color. use rock mulches to create patterned and textured ground treatments. • Implement a ground treatment retrofit program to treat areas of bare soil.

NATIVE REVEGETATION SOFTSCAPE TREATMENT 21.8 Carefully select native plant species. 21.7 Apply native revegetation softscape In addition to plant species identified in along open, rural highways. Mapping Ecosystems along Nevada High- Reestablish the native conditions using the ways and the Development of Specifications native plant revegetation softscape type. The for Vegetation Remediation (Tueller, et al native plant revegetation softscape type is 2002), use the list of native plant species the background planting for the majority of provided for revegetation efforts. Plant the corridor and should be implemented as palettes are not restrictive. They provide a indicated in the landscape design segments. starting point for plant selection.

• Roadsides should be revegetated after a • Ensure the plant palette selected for the fire to reduce erosion. site complements existing desirable veg- • Plant density and spacing should mimic etation in the surrounding landscape. surrounding conditions, incorporating • Salvage existing native plants and topsoil scattered rock mulch to reduce erosion prior to construction. Species salvagabil- and improve revegetation success. ity depends on size, location, soils, and • Select an appropriate native plant pal- analysis of plant value, including the po- ette. Sites should be evaluated for eleva- tential survival rate. Salvaged plants can tion, soil conditions, and ecosystem type readily improve the roadside aesthetic by (for example, riparian, playa, or salt flat). providing mature plants that would nor- mally take many years to establish. Where (1) The native plant palette near Searchlight includes a wide variety of plant colors, shapes, and heights. 3.41 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

existing native plants cannot be re-used, tion (Tueller et al, 2002). Tueller’s report Figure 14 - Native Revegetation Plant Palette chip salvaged plants and incorporate into offers a complete description of suitable Height x Width Exposure to sun Water Requirement Seasonal the topsoil. In addition, ensure native plant species and plant communities, soil topsoil is collected and stored for reuse. classification units, and best manage- North of Las Vegas Valley Lower Mojave/Creosote Zone Native topsoil provides a seed source and ment practices for vegetation remedia- Shrubs: important bacteria for salvaged plant tion, and should be used as a guide for Atriplex hymenalytra - Holly Leaf Saltbush 5’ x 8’ Full sun Low water use Spring establishment and growth. Carefully re- revegetation. Atriplex lentiformis - Quailbush 8’ x 8’ Full sun Low water use Spring Coleogyne ramosissima - Blackbrush 5’ x 6’ Full sun Low water use Spring move, stockpile, and store the native top- • Salvage existing native plants and topsoil Larrea tridentata - Creosote Bush 10’ x 10’ Full sun Low water use Spring soil of new construction projects to be prior to construction. Species salvagabili- used as final bedding material. Ensure na- ty depends on location, soils, and analysis Accents: tive soil stockpiles are protected from the Echinocereus triglochiadatus - Red Hedgehog Cactus .4’ x 1.25’ Full sun Low water use Year-Round of plant value, including the potential sur- Ferocactus cylandraceous - Barrel Cactus 3’ x 1.5’ Full sun Low water use Sp/Sum wind to avoid erosion and the creation of vival rate. Salvaged plants can be utilized Opuntia basilaris - Beavertail Cactus 1’ x 3’ Full sun Low water use Spring a dust hazard. Organic mulches may be at revegetation sites to improve roadside Opuntia echinocarpa - Silver Cholla 3’ x 3’ Full sun Low water use Spring used to improve soil quality. Firmly an- aesthetics and to provide mature plants Mammillaria tetrancistra - Mojave Fishhook Cactus 5’ x 2’ Full sun Low water use Spring chor mulches to the site. Carefully ana- Yucca schidigera - Mojave Yucca 12’ x 6’ Full sun Low water use Spring that would otherwise take years to es- Yucca brevifolia - Joshua tree 30’ x 15’ Full sun Low water use Spring lyze the site to determine the need for tablish. In addition, ensure native topsoil fertilizers and pH amendments. is collected and stored for reuse. Native South of Las Vegas Valley Blackbrush Zone; Corridor Crosses Creosote-Bursage and Blackbrush Zones • Salvage and stockpile native rock mulch. topsoil provides a seed source and im- Trees: Existing rock naturally blends with the portant bacteria for salvaged plant estab- Acacia greggii - Catclaw 25’ x 15’ Full sun Low water use Sp/Fall landscape. Re-use of existing materi- lishment and growth. Carefully remove, Chilopsis linearis - Desert Willow 20’ x 15’ Full sun Low/Mod water use Sp/Fall als should be considered as part of site stockpile, and store the native topsoil of Prosopis glandulosa - Honey Mesquite 25’ x 35’ Full sun Moderate water use Summer design. new construction projects to be used as Shrubs: • Additional plants not included in the ad- final bedding material. Ensure native soil Coleogyne ramosissima - Blackbrush 5’ x 6’ Full sun Low water use Spring stockpiles are protected from the wind to Eriodictyon angustifolium - Yerba Santa 4’ x 6’ Full sun Low water use Sp/Sum jacent list can be included upon review Erigonum wrightii - Wright’s Buckwheat 2’ x 3’ Full sun Low water use Summer and approval. avoid erosion and the creation of a dust Erigonum fasciculatum v. poliofolium - Flattop Buckwheat 3’ x 4’ Full sun Low water use Spring hazard. Organic mulches may be used Fallugia paradoxa - Apache Plume 6’ x 4’ Full sun Low water use Spring to improve soil quality. Firmly anchor Psorothamnus fremontii - Indigobush 5’ x 5’ Full sun Moderate water use Sum/Fall 21.9 Utilize proper revegetation methods. mulches to the site. Carefully analyze the Salvia mojavensis - Mojave Sage 3’ x 3’ Full sun Low water use Spring site to determine the need for fertilizers Accents: and pH amendments. Agave utahensis - Utah Agave 5’ x 8’ Full sun Low water use Sp/Sum • Reestablish native conditions using the Mirabilis froebelii - Desert Four O’Clock 4’ x 4’ Full sun Low water use Summer native plant revegetation softscape • Apply a prescribed soil treatment such as Opuntia erinacea - Old Man Cactus 2’ x 4’ Full sun Low water use Spring type. Select perennial grasses, forbs, and plowing, disking, harrowing, furrowing, Opuntia acanthocarpa - Buckhorn Cholla 4’ x 3’ Full sun Low water use Spring shrubs that can be established with little hydroseeding, applying mulches (such as Yucca baccata - Banana Yucca 3’ x 3’ Full sun Low water use Summer Yucca schidigera - Mojave Yucca 12’ x 6’ Full sun Low water use Spring or no maintenance over the long term. In- straw), and using tackifiers (such as dark corporate the Native Wildflower Program colored netting). Soils should be rough- Grasses: in revegetation efforts. Select plants ened before and after planting to create Achnatherum hymenoides - Indian Ricegrass 2’ x 2’ Full sun Low water use Spring that have been evaluated for drought favorable seed sites, particularly for grass Bromus rubens - Red Brome 1’ x .5’ Full sun Low water use Winter Hilaria rigida - Big Galleta 1’ x .5’ Full sun Low water use Spring tolerance, salt and alkali tolerance, seed- and forb seeds. In silty conditions, a soil Stipa speciosa - Desert Needlegrass 1’ x .5’ Full sun Low water use Summer ling vigor, fire retardant characteristics, stabilizer, such as a hydromulch, or a mat- growth habit, suitable soil groups, seed- ting material can reduce potential dust Wildflowers: problems. On some sites, deep ripping Wildflowers like the Prince’s Plume (Stanleya pinnata) and the Apricot-Mallow (Sphaeralcea ambigua) can be planted but if the soil is harvested ing rates, Pure Live Seed (PLS), availability, and carefully maintained – all the necessary seeds should be contained within the soil. In the interest of preserving the most natural landscape and general costs of native seed sources. can loosen hardpan and improve seeding and avoiding breaks in type or structure of vegetation – harvesting and re-using topsoil from the same area without wildflower re-seeding Ecosystem categories and suitable plant success. In conditions of steep cuts and should provide an abundance of wildflowers native to that area. species have been identified for reveg- slopes greater than 40%, slope disking may create seed pockets. Use scattered Native penstemons for Mojave: etation specifications along Nevada’s Penstemon eatoni - Eaton’s or Firecracker Penstemon 2’ x 3’ Full sun Low water use Spring highways in Mapping Ecosystems Along rock mulch in coordinate with revegeta- Penstemon parryi - Parry’s Penstemon 4’ x 2’ Full sun Low water use Spring Nevada Highways and the Development tion. This mulch provides seed pockets Penstemon utahensis - Utah Penstemon 1’ x 1.5’ Full sun Low water use Spring of Specifications for Vegetation Remedia- and protects plant establishment. Penstemon palmeri - Palmer’s Penstemon 4’ x 2’ Full sun Low water use Spring 3.42 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

• Collect native seed. Initiate a process for • Develop a program to control noxious native seed collection at the start of each weeds and invasive plant species. In areas project where revegetation is designat- requiring revegetation, quickly established. Native seed should be collected from ing native species is the most effective a site in close proximity to the revegeta- method of controlling invasive species. tion area. Because unpredictable weather In much of the corridor, however, re- patterns can affect seed availability, plan establishing native plant communities ahead to ensure usable seed. Native seed may take many years. Use biotic or or- can also be purchased through seed com- ganic forms of control, such as tempo- panies or BLM nurseries. rary mulches, to prevent invasive species • Monitor revegetation during construc- from establishing. Provide regular and tion to ensure that specified materi- frequent monitoring of new plantings to als and installation methods have been identify when additional forms of control used. Plan and budget for maintenance may be needed. of revegetation and weed control areas until the desired species are established. In addition, continue to monitor revegetation plantings for up to five years after construction to ensure success- (1) Native revegetation is appropriate for highway medians in rural settings. ful establishment. Include temporary irrigation if needed. Provide training for NDOT staff who oversee revegetation administration. Failures in revegetation can often be attributed to poor installation and maintenance practices.

(2) Native revegetation softscape types should be used to repair and restore roadsides along the majority of the highway.

3.43 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

ENHANCED NATIVE SOFTSCAPE TREATMENT • Use existing vegetation as a cue to select- Figure 15 - Enhanced Native Plant Palette ing appropriate plant species Height x Width Exposure to Sun Water Requirement Seasonal Interest 21.10 Apply enhanced native softscape along tran- Trees: sition zones and as part of simple gateway • Additional plants not included in previous Salix exigua - Coyote Willow 10’ x 6’ Partial sun Moderate water use Spring palettes or the adjacent list may be included Prosopis glandulosa - Honey Mesquite 25’ x 35’ Full sun Moderate water use Summer treatments. upon review and approval Prosopis pubescens - Screwbean Mesquite 25’ x 25’ Full sun Moderate water use Spring Enrich the native softscape palette with the Quercus turbinella - Desert Scrub Oak 8’ x 12’ Full sun Mod/Hi water use n/a Acacia minuta - Sweet Acacia 20’ x 20’ Full sun Low water use Spring enhanced native softscape type. The enhanced Prosopis chinensis - Chilean Mesquite 25’ x 40’ Full sun Moderate water use Summer Vitex agnus-castus - Chaste Tree 25’ x 25’ Full sun Moderate water use Summer native softscape type is the second most com- Cercidium microphyllum - Foothills Palo Verde 20’ x 20’ Full sun Moderate water use Summer monly used plant palette throughout the cor- Prosopis velutina - Velvet Mesquite 25’ x 30’ Full sun Moderate water use Spring Cercis occidentalis - Western Redbud 10’ x10’ Full/Partial sun Moderate water use Spring ridor and should be utilized as shown in the Shrubs: landscape design segments. Encelia farinosa - Brittlebush 3’ x 4’ Full sun Low water use Spring Cassia nemophila - Desert Cassia 6’ x 6’ Full sun Low water use Spring Eremophila spp. - Valentine or Emu Bush 4’ x 4’ Full sun Low/Mod water use Winter • Typical applications are specified for tran- Zauschneria californica - Hummingbird Flower 2’ x 3’ Full sun Low water use Sum/Fall sition zones into communities as well as simple gateway treatments. The enhanced Accents/Grasses: Tetraneuris acaulis - Angelita Daisy 1’ x 1.5’ Full/Part sun Moderate water use Sp/Sum/Fall native softscape type enriches the Mojave Baileya multiradiata - Desert Marigold 1’ x 1’ Full/Part sun Low water use Sp/Sum/Fall Desert plant palettes with a mix of vertical Psilotrophe cooperi - Paper Flower 1’ x 1.5’ Full/Part sun Low/Mod water use Sp/Sum/Fall heights and densities. Opuntia engelmannii - Engelmann’s Prickly Pear 6’ x 10’ Full sun Low water use Sp/Sum Opuntia santa-rita - Santa Rita Prickly Pear 4’ x 6’ Full sun Low water use Year round • A variety of native species are planted in Scleropogon brevifolius - Burrograss 1’ x 1’ Full sun Low water use Spring moderately dense patterns to create this Note: See Native Revegetation Plant Palette for more plant options. landscape. • Enhanced native softscapes use the plant material of the native revegetation palette as a base and add a limited number of regionally adapted trees, shrubs, and other materials for diversity in form. Plants are placed in massings and at a closer proximity to one another than in the surrounding native landscape.

21.11 Carefully select enhanced native plant species. In addition to the plants listed in the native plant revegetation landscape type, the following list of plants comprise the enhanced native landscape type. Use these species to create plant communities with variations in plant height and width.

• Ensure the plant palette selected for the site complements existing vegetation in (1) Enhanced native softscape type utilizes greater plant massing and begins to add more color, the surrounding landscape. texture, and verticality to the native palette.

3.44 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

REGIONALLY ADAPTED SOFTSCAPE TREATMENT Figure 16 - Regionally Adapted Plant Palette Height x Width Exposure to sun Water Requirement Seasonal 21.12 Apply regionally adapted softscape in ur- Trees: ban areas and locations of high visibility. Fraxinus oxycarpa - Raywood Ash 35’ x 25’ Full sun Moderate water use Spring Fraxinus velutina ‘Rio Grande’ - Modesto Ash 50’ x 30’ Full sun Moderate water use Spring Use the regionally adapted softscape type Gleditsia triacanthos inermis - Thornless Honey Locust 35’ x 25’ Full sun Moderate water use n/a Ulmus parvifolia - Drake Elm 60’ x 70’ Full sun Moderate water use Fall where identified in each landscape design Cupressus arizonica - Arizona Cypress 70’ x 30’ Full sun Low/Mod water use n/a segment. This softscape type utilizes the Eucalyptus microtheca - Coolibah Tree 40’ x 25’ Full sun Moderate water use n/a Acacia stenophylla - Shoestring Acacia 30’ x 15’ Full sun Low water use Spring Mojave, Sonoran, and Chihuahuan plant pal- Eysenhardtia orthocarpa - Kidneywood 10’ x 6’ Full sun Moderate water use Spring Rhus lanceolata - Flame Leaf Sumac 15’ x 15’ Full sun Low water use Summer ettes along with other low-water use plants Ungnadia speciosa - Mexican Buckeye 15’ x 15’ Full/Part sun Moderate water use Spring that are well adapted to local conditions. Celtis pallida - Desert Hackberry 8’ x 10’ Full sun Moderate water use n/a

Shrubs: • Typical applications include welcome Buddleia davidii - Navajo Purple Butterfly Bush 8’ x 6’ Full/Part sun Low water use Spring Senna phylodenia - Silver Leaf Cassia 6’ x 6’ Full/Part sun Low water use Spring centers, gateways, rest areas, urban ar- Dodonea viscosa - Hopbush 10’ x 6’ Full sun Low water use Year round eas, and other high visibility locations Rhus ovata - Sugar Bush 10’ x 10’ Full/Part sun Low water use Spring • Plants are arranged in greater densities, Salvia clevelandii - Chaparral Sage 4’ x 6’ Full sun Low water use Spring Phlomis fruticosa - Jersualem Sage 4’ x 3’ Full sun Moderate water use Sp/Sum forming overstory and understory lay- Justicia californica - Chuparosa 3’ x 3’ Full/Part sun Moderate water use Summer ers, to create a richness of color, texture, Tecoma x ‘Goldstar’ - Texas Yellow Star 20’ x 8’ Full sun Moderate water use Summer form, and seasonal change, enhancing Senna oligophylla ‘Outback’ - Outback Cassia 3’ x 3’ Full sun Low water use Sp/Sum

the desert garden Cacti/Accents/Grasses/Groundcovers and Perennials: 21.13 Carefully select regionally adapted plant Fouquieria splendens - Ocotillo 18’ x 10’ Full sun Low water use Spring Coreopsis lanceolata - Sunray 1.5’ x 1’ Full sun Moderate water use Sp/Sum species. Hemerocallis spp. - Daylily 2’ x 2’ Full/Part sun Low water use Spring Nolina microcarpa - Bear Grass 4’ x 6’ Full sun Low water use Spring Use regionally adapted plant species. In ad- Penstemon spectabilis - Showy Penstemon 3’ x 2’ Full sun Low water use Spring dition to the plants listed in the revegeta- Salvia leucantha - Mexican Bush Sage 3’ x 3’ Full sun Moderate water use Sp/Fall/Win Dasylirion wheeleri - Desert Spoon 4’ x 6’ Full/Part sun Low water use Sum/Fall tion landscape type and the enhanced native Hylotelephium x ‘Autumn Joy’ - Autumn Joy Sedum 1.5’ x 1.5’ Full/Part sun Low water use Sp/Sum Bulbine frutescens - Shrubby Bulbine 1’ x 2’ Part sun Low water use Sp/Fall landscape type, the following list of plants Note: See Native Revegetation and Enhanced Native Plant Palettes for more plant options. should be used to comprise the regionally adapted landscape type.

• Use plant species to create plant communities with variations in plant height and spread • Additional plants not included in previous palettes or the adjacent list may be included upon review and approval

(1), (2) Regionally adapted softscape planting introduces non-native species that are adapted to the desert climate.

3.45 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

REGIONAL ORNAMENTAL SOFTSCAPE TREATMENT • Additional plants not included in previ- Figure 17 - Regional Ornamental Plant Palette Height x Width Exposure to Sun Water Requirement Seasonal Interest 21.14 Apply regionally ornamental softscape ous palettes or the adjacent list may be included upon review and approval Trees: in areas of extremely high importance. Olea europea ‘Swan Hill’ - Fruitless Olive Tree 30’ x 30’ Full sun Moderate water use Summer Pinus eldarica - Mondel Pine 50’ x 30’ Full sun Moderate water use Summer Use the regional ornamental softscape type Pistacia chinensis - Chinese Pistache 40’ x 20’ Full sun Moderate water use Fall Sophora secundiflora - Mescal Bean 15’ x 10’ Full sun Moderate water use Spring to create cultural meaning, enhance a land- Pithecellobium flexicaule - Texas Ebony 20’ x 15’ Full/Part sun Moderate water use Sp/Sum mark feature, or both. The regional orna- Palms: mental softscape type is the rarest treat- Chamaerops humilis - Mediterranean Fan Palm * 20’ x 20’ Full sun Low/Mod water use Summer ment and should be used where identified Phoenix dactylifera - Date Palm* 50’ x 25’ Full sun Moderate water use Year round Trachycarpus fortunei - Windmill Palm* 20’ x 20’ Full/Part sun Moderate water use Year round in the landscape design segments. Washingtonia filifera - California Fan Palm* 50’ x 15’ Full sun Low/Mod water use Summer

Shrubs: • It is typically used in areas of extreme Caesalpinia mexicana - Mexican Bird of Paradise 10’ x 6’ Full sun Moderate water use Summer high importance as part of placemaking Caesalpinia pulcherrima - Red Bird of Paradise 8’ x 8’ Full sun Moderate water use Summer Ceasalpinia gillesii - Yellow Bird of Paradise 7’ x 7’ Full sun Moderate water use Sp/Sum/Fall • This softscape type emphasizes the Calliandra eriophylla - Fairy Duster 4’ x 4’ Full/Part sun Low Sp/Sum/Fall unique cultural elements of a particular Eleagnus x Ebbingei - Ebbing’s Silverberry 9’ x 9’ Full sun Moderate water use Summer Rosmarinus officinalis - Spreading Rosemary 2’ x 8’ Full sun Moderate water use Summer urban environment Caryopteris x clandonensis ‘Dark Knight’ - Blue Mist 3’ x 4’ Full sun Moderate water use Sum/Fall • The use of non-native, ornamental plant Justicia spicigera - Mexican Honeysuckle 3’ x 4’ Full/Part sun Low/Mod water use Sp/Sum/Fall

species in this softscape type accentu- Accents/Cacti and Grasses: ates the composition possibilities inher- Agave vilmoriniana - Octopus Agave 4’ x 4’ Full sun Low water use n/a ent in form and color Agave bracteosa - Spider Agave 2’ x 3’ Full/Part sun Low water use n/a Dasylirion longissimum - Sotol 6’ x 4’ Full sun Low water use n/a • Dynamic ornamental forms, colors, and Drosanthemum hispidum - Ice Plant 2’ x 3’ Full sun Low/Mod water use Spring textures enhance the native Mojave Euphorbia charachias - Shrubby Spurge 3’ x 2’ Full/Part sun Moderate water use Win/Sp Desert landscape in complementary pat- Hesperaloe parviflora ‘Yellow’ - Yellow Hesperaloe 4’ x 4’ Full sun Low water use Sp/Sum/Fall Muhlenbergia capillaries ‘regal mist’ - Regal Mist 3’ x 6’ Full/Part Moderate water use Spring terns Phormium tenax - New Zealand Flax 15’ x 4’ Partial sun Low/Mod water use Sp/Sum 21.15 Carefully select regional ornamental plant Pennisetum setacum ’rubrum’ - Red Fountain Grass 3’ x 3’ Full sun Moderate water use Year round Note: See Native Revegetation, Enhanced Native, and Regionally Adapted Plant Palette for more plant options. species. *Palm trees should rarely be used along the corridor. Species should only be chosen in areas of extremely high visual importance such as the In addition to the plants listed in the Re- resort corridor in Las Vegas. vegetation landscape type, the enhanced native landscape type, and the regionally adapted landscape type, the following list of plants comprise the regional ornamental landscape type.

• The species listed represent those plants with significant cultural value. • Alternative plants that have the same form and characteristics, thereby evok- ing a similar cultural meaning, may be more desirable if the alternative plant is better suited to the environmental conditions, requires less maintenance, and is (1) The regional ornamental softscape type requires (2) The regional ornamental softscape type adds permanent irrigation and is used to highlight points of to the identity and placemaking of areas of high more drought-tolerant. significant interest and landmark quality. importance. 3.46 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

22.0 WILDLIFE CROSSINGS AND PROTECTION the size of the underpass as the length fence with 6 inches located below ground 22.6 Retrofit existing highway facilities within 22.1 Engage appropriate agencies in the planning increases. to prevent tortoises from crawling under the Destiny of the West Landscape Design the fence along both sides of the highway. and design of wildlife crossings. • Restore vegetation leading up to wildlife Segment to restore wildlife migration pat- crossings and provide cover to shield the Secure the fence to a culvert that crosses terns. Engage federal, state, and local agencies and entrance to each wildlife crossing from beneath the road. wildlife professionals in the initial stages of the road while maintaining clear visibility • Recommended fencing heights for big- Consider broad areas within the landscape planning and design through implementa- through the crossing. horn sheep or deer is eight feet, variable- where existing topography provides oppor- expanded metal mesh fence. Metal mesh tion of wildlife crossings. • Within underpasses, incorporate natu- tunities. Coordinate location with migration fencing should be fastened to metal wire. rally-occuring materials that exist in adja- corridors. cent areas. Barbed wire is unacceptable. Fencing • Coordinate information on historic migra- should occur on both sides of the road, • Wildlife underpasses or overpasses com- tory routes and daily wildlife movements and should extend to the underpass or bined with fencing have the highest doc- 22.7 Design wildlife crossing structures to blend to situate crossing structures in appropri- overpass entrance. umented rates of success for large and with surrounding landscape. ate locations. • Incorporate breaks, known as jump-outs, small animals. Most successful crossing Visually screened bridges and culverts recede • Research information on the occurrence structures are open-span bridges with in areas with continuous fencing to en- into the landscape. Combine recreational of wildlife-related automobile accidents, sloping sidewalls. able wildlife trapped within the road corri- and explore designs to minimize these dor to escape and return to habitat areas. trails and wildlife crossings as part of bridge collisions. • Road underpasses may be constructed of concrete boxes, elliptical metal culverts, and culvert crossings where feasible. or open span bridges. Increased width 22.4 Develop a monitoring system for all major 22.2 Use ecologically-appropriate wildlife cross- and height of structures usually correlate wildlife crossings to document crossing use ing structures that meet the needs of spe- with increased use by large mammals. Siz- es range from 6.5 by 6.5 foot culverts for and to collect data for similar projects. cific wildlife species in order to improve small animals, to an opening width of 40 Several studies in other states indicate that movement corridors and safety along the feet by a height of 16 feet for larger ani- significant movement and migratory disrup- corridor. mals. Use natural bottoms for all underpasses that also accommodate streams or tions have occurred due to highway con- Analyze wildlife behavioral traits to design drainage patterns. Determine the actual struction. Movement and behavior at cross- effective crossing structures that meet the size, location, and type of structure on a ings and other highway locations should be needs for all species that will use a structure. site by site basis. monitored to help improve success of these • Placement of underpasses in relation to facilities as part of an on-going interagency • Specific design criteria varies with each an animal’s habitat is crucial. The habi- species. Consider larger species, such as tat within the crossing structure should cooperative research. also be enhanced to encourage use by deer, and small species such as coyotes. (1) Wildlife underpasses help maintain wildlife migration wildlife. • Ensure structures complement the pri- 22.5 Include observation points and watch- patterns and minimize vehicle/wildlife interaction. • Limit human use of the underpass struc- mary defense strategy for each wildlife able wildlife opportunities in the design of species. For instance, animals such as deer, tures when possible. elk, pronghorn, and bighorn sheep depend crossings. on good visibility as a key defense mecha- Consideration should only be given when ob- 22.3 Use different types of fencing as appropri- nism. servation points do not interfere with wild- ate for different animals. • Use open-span bridges and culverts that life movement. are oriented perpendicular to the road in order to reduce the overall length and im- • At tortoise migration routes, use an 18 prove visibility. Proportionately increase inch to 24 inch high welded-wire mesh

3.47 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

23.0 CONSTRUCTION PRACTICES diversion earth forms, vegetative buffer 23.1 Clear the site only within the limits of areas, channel linings, energy dissipaters, seeding and mulching. construction. 23.4 Carefully manage and dispose of waste Avoid the visual scars and plant disturbance material. from excessive site disturbance. Asphalt millings inhibit slope revegetation, contaminates adjacent soils, and create a 23.2 Protect important environmental, land- cluttered, unfinished appearance. scape, and cultural features. Identify and protect all areas to be preserved • Avoid placing disposed milled asphalt on prior to construction. These include trees, highway shoulders. shrubs, landscape and cultural features, and environmentally sensitive areas. 23.5 Salvage and store topsoil and native plant materials. (1) The placement of asphalt millings on the highway shoulder creates a stark contrast between • Fence areas where vegetation is to re- the road and the adjacent undisturbed landscape and should be avoided. main, avoid disturbance and compaction After soil erosion and sediment control of the ground. measures have been implemented and be- • Maintain and enhance existing ground- fore grading work begins, remove and store cover to ensure the area is left in a condi- topsoil for project reuse. tion consistent with the surroundings. • Salvage areas should be designated on 23.3 Utilize Best Management Practices and ap- plans and staked on the site. propriate short term stabilization measures • Salvaged plant materials should be stored to prevent erosion and sedimentation dur- and maintained during construction, pri- or to replanting. ing construction. • Stripped topsoil in excess of the quantity Perform a site risk assessment prior to con- required for the project should be stored struction to determine the threat of intro- at specified locations for future use. ducing sediments and pollutants into near- • Topsoil of lesser quality can be blended by surface waters and drainage systems. with soil amendments to improve condition for final bedding. • Utilize short-term BMP’s to reduce sedimentation and pollutant run-off during 23.6 Carefully consider location/reclamation of construction. construction areas. • Consider site specificity, timing of exe- Construction staging areas, borrow pits, cution, and application of man-made devices and/or vegetative or organic cover and other construction areas must be care- to stabilize banks during construction. fully located and returned to a condition • Research alternatives to hard surface that is equal to or better than original, and paving. consistent with the Corridor Plan design • Give preference to other sediment con- guidelines. trol devices including sediment basins, 3.48 SECTION FOUR: Highway Facilities Guidelines Chapter Three — Design Guidelines

24.0 MAINTENANCE FACILITIES AND 24.3 Consult Best Management Practices and pro- • Ensure structures can be readily patched PRACTICES vide for efficient and effective maintenance or painted with matching colors. When paint or stain repair is made, make sure of landscape and aesthetic treatments. 24.1 Locate and screen maintenance staging ar- repairs cover the entire surface and ex- eas in visually unobtrusive areas. With few exceptions, new landscape and tend to joints and logical edges. Maintenance staging areas should be ad- aesthetics projects are designed to be low • Use anti-graffiti treatment on detailed equately set back from the highway. Where maintenance. Refer to NDOT Landscape and sculptural elements. possible, site facilities so they are screened Aesthetics Maintenance Manual. Provide • District level maintenance teams should use the same color palette for all mainte- from the highway by existing landforms. areas where maintenance equipment can nance and repairs (refer to Color Palette be conveniently located. Consider main- guideline, page 3.23, for more informa- • Screen maintenance areas, particularly tenance routines required for the design tion). stockpiles, borrow pits, and equipment, program, and identify areas that may need • If no logical edge or joint exists, feather (1) Screening maintenance facilities from the road is recommended and helps minimize visual clutter in the traveler’s view from the highway or from adjacent de- edges of paint. veloped property. additional care or attention initially and/or of the larger landscape. • Consider security fencing, landscape, and as the project matures. NDOT maintenance architectural solutions. practices include: 24.5 Avoid pruning or shearing plant material except as required to remove dead, dam- Grading and drainage is the most important • Trash and debris removal. aged, or diseased plant part or to provide consideration in the site planning and design • Surface finish maintenance (painting, clear visibility for traffic conditions. patching, graffiti removal). of a maintenance area in order to prevent • Grading and earthwork. any environmental damage that could result • Ground treatment (raking, replacing from leachates in salt and gravel stockpiles. mulch or decorative rock, reconfiguring The NDOT Best Management Practices Man- drainage structures). ual outlines additional points for consider- • Weed control. ation when planning for maintenance stag- • Plantings (interim, temporary, and per- ing areas including the following: manent irrigation, trimming, pruning of shrubs and trees, manual weed control, fertilizing). • Cover salt and sand piles to avoid water- course and groundwater degradation. • Disease and pest management (including invasive species control). • Provide space for equipment storage, vehicles, and supplies, as well as employee • Repair and replacement of structural and or visitor parking. electrical components, irrigation, signage, and lighting. • Consider future expansion needs.

24.4 Create a visual design unity among all 24.2 Coordinate with maintenance personnel when existing and new structures based on the planning and designing maintenance areas. design theme. Planning and design of maintenance areas Ensure a visual design relationship exists requires close cooperation between design- among all highway structures. This includes ers and the personnel directly responsible coordinating materials, patterns, and color. for its use. 3.49 Chapter Three — Design Guidelines SECTION FOUR: Highway Facilities Guidelines

25.0 RECOMMENDATIONS FOR porate alternative energy sources. Where SUSTAINABLE HIGHWAY possible, use solar powered electronic signs, low energy use lights (such as LED), ENVIRONMENTS and passive solar design. 25.1 Use three key principles in highway con- • Use recycled materials for construction. struction and natural resource management When applicable, use reclaimed concrete to create sustainable highway environment and asphalt, scrap tires, plastics, steel slag, roofing shingles, coal fly ash, and – avoid, minimize, and mitigate. composted municipal organic wastes. Concepts central to these principles include: • Reduce waste. Waste reduction concepts include right-of-way management, re-use • Water conservation: efficiency, protec- of organic materials, water conservation, tion, and reuse and selection of long-lived materials. • Construction materials selection: reduce, reuse, and recycle 25.3 Utilize sustainable development principles • Air quality protection in the design and construction of the high- • Energy efficiency: use renewable energy way corridor. • Design innovation Sustainable design is a holistic philosophy

that includes all aspects of function and (1) Solar power provides (2) Wind power generates a clean (3) Consider recycled and reclaimed 25.2 Techniques for creating sustainable high- construction operations including, but not a sustainable, renewable renewable energy source and materials, such as plastic modular units, way environments. energy source for lighting should be used if available. for roadway construction. limited to: energy use, air quality, material in remote areas. selection, energy generation, water con- • Develop systems to encourage sustain- servation, heating, solid waste, habitat en- able highways. Develop performance standards, monitoring procedures, and hancement, and protection. promote coordination between environmental and transportation agencies. • Consider sustainability in both the design • Preserve air quality. Use construction and construction of highway systems. mitigation techniques to minimize dust • Restore disturbed man-made and natural from construction sites. habitats. • Minimize energy consumption and incor-

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