The Need for a Design Handbook
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Chapter 1. Introduction The need for a Design Handbook The growth in trails The continuing increase in trails reflects Floridians’ interest in outdoor recreation and growing participation in bicycling, In 1994 Florida had 1081 kilometers (670 miles) of off-road walking, and skating as healthy, environmentally low impact, multi-use trails that are used by bicyclists, skaters, and efficient, and fun ways to get around. pedestrians for both transportation and recreation.1 Because of their popularity, the number and miles of trails is growing The growth in trails also reflects many people’s enjoyment of rapidly. physical separation from motorized traffic. Segregation allows trail users to avoid the pollution, noise, and intimidation they perceive from motor vehicles, and the potential for an injury- producing crash. While trails do provide for segregation from motor vehicle traffic along most of their length, they inevitably intersect with roadways and driveways, resulting in varying levels of integration and thus conflict with motorized traffic. It is at junctions where the potential for serious crashes lies. Crashes and the difficult task of crossing a junction Numerous studies have well established that roadway junctions are over represented locations for bicyclist- and pedestrian- motor vehicle crashes. In a recent nationwide sample, it was found that 57 percent of The proposed South Dade Greenway Network will ultimately be a system pedestrian and 73 percent of bicyclist crashes occurred at of 10 interconnecting trails that total 313 km (194 mi) (256 km/159 mi are junctions.3 Another study examining police-reported bicycle- off-road). One hundred thirty-two kilometers (82 mi) are currently motor vehicle collisions covering a four-year period in Palo programmed for improvements, and the entire SDGN could be completed Alto, California found that 74 percent occurred at a junction.4 by 2005.2 1-1 Chapter 1. Introduction The need for a Design Handbook Considering the complexity of crossing a junction, it is no The lack of guidelines wonder that the majority of crashes occur here. Quality resources are available concerning the planning and construction of trails, but few guidelines for trail-roadway A person simply walking across the street faces many intersection design are available. Publications typically lack difficulties—gap selection, turning vehicles, uneven terrain, specific detail regarding trail crossing arrangements, or are obstacles (e.g., bollards), and other trail users. Consider then from foreign countries, thus raising questions regarding the task of a novice in-line skater who also has to deal with the applicability to the U.S. challenges of staying upright and stopping. Trail Intersection Design Guidelines addresses the details Because of the complexity of crossing an intersection and associated with trail-roadway intersection design, and human limitations, the following problems on the part of trail incorporates U.S. roadway design principles with domestic and users and motorists alike can readily arise and lead to crashes: international trail design standards. It is intended to be the most comprehensive resource to date specifically addressing < errors in gap judgement; trail junctions. < inattention; < poor visual search; < improper expectations; Conclusions < haste. Inevitably there will be a substantial increase in the number (and miles) of trails, trail-roadway and -driveway junctions, trail users, and in the potential number of trail user-motor “Street crossing is a learned, socialized behavior which vehicle conflicts and crashes. Therefore it is vital to have a we now understand to be much more complex than manual that provides guidelines to assist in designing these many behavior modification advocates would have us trail junctions so that operations and safety are maximized, and believe.”5 the number of conflicts and crashes are minimized. Due to the inherent conflict at junctions, the need for careful Michael R. Hill design is evident. Careful design is especially important at trail junctions because of the vulnerability of trail users and because of the variability in the characteristics of trail users who come 1-2 Chapter 1. Introduction The need for a Design Handbook in all ages, sizes, and capabilities. Trail users are indeed a diverse “design” group which requires planners and engineers to pay special attention to the details of intersection design. While completely eliminating all intersection problems is not always feasible, careful design can reduce the number of incidences and lessen the consequences when they do occur. Trail Intersection Design Guidelines is the result of: < a limited literature review of designs and standards currently in use abroad and in the U.S.; < a theoretical view of an inherently safe road traffic system, resulting in principles for the safe design of trail-roadway Diverse trail users intersections; < observations at approximately 60 trail intersections throughout Florida, and detailed research involving approximately 60 hours of video recording conducted at a subset of 20 of these, all along the Pinellas Trail. Literature review Elements of bicycle and pedestrian planning and intersection design from the following principle sources are imbedded throughout these design guidelines. 1-3 Chapter 1. Introduction Development of the Handbook European United States Main roads in Urban Areas; Bikes and Pedestrians6 from Project Task 16: Evaluation of Issues In Planning And Design Finland, and Sign Up for The Bike7 from The Netherlands offer of Bicycle Trail-Highway Crossing10 produced by the significant detail on accommodating bicyclists both on and off Pennsylvania Transportation Institute at The Pennsylvania road, including intersection design. Both contain a wealth of State University for the Pennsylvania Department of information that contributed greatly throughout this document. Transportation was the only domestic resource of information But these documents are too broad in scope to thoroughly that considered many of the critical issues of trail intersections cover all aspects of trail intersection design, and all lack a such as sight distance, signs, and pavement markings. This United States context. excellent document, while detailed, does not deal with the full breadth of considerations including access control and refuge A third document, Making Ways for the Bicycle,8 was produced islands, for examples. by Sustrans, a British civil engineering charity which designs and builds traffic-free routes for cyclists, walkers, and people Trails For The Twenty-first Century,11 and Greenways: A with disabilities. This attractive 56-page design manual is Guide to Planning, Design, and Development12 are very principally concerned with building a trail, and devotes only attractive trail design publications that cover all aspects of two pages to intersection design. building a trail in detail, but are light on road crossing specifics. Canada The “bibles” of roadway and bikeway design, the Manual on The Technical Handbook of Bikeway Design9 was produced by Uniform Traffic Control Devices (MUTCD)13, Traffic Control a bicycle advocacy organization known as Velo Quebec in Devices Handbook,14 A Policy on Geometric Design of collaboration with the Ministry of Transport of Quebec and the Highways and Streets,15 known as the AASHTO “Green Canadian International Development Agency. The handbook Book,” and the Guide for the Development of Bicycle offers recommendations and guidelines in an effort to ensure Facilities16 are referred to throughout this document. The that “all bicycle facilities created in the next decade will be Design and Safety of Pedestrian Facilities,17 a monograph built to the highest possible standards.” prepared by the Institute of Transportation Engineers (ITE) technical council committee 5A-5, also provided valuable information. 1-4 Chapter 1. Introduction Development of the Handbook Greenways, Inc., of Cary, North Carolina, is a planning and < Pinellas Trail in the Clearwater/St. Petersburg area landscape architecture firm that specializes in the design of < State Road 84 Bike Path in Fort Lauderdale greenways, rail-trails, and urban bicycle and pedestrian < M Path in Miami. systems. This organization produced an illustrated technical memorandum describing how six trails in the U.S. have dealt The observed junctions were as diversified as the geographic with roadway crossings. locations themselves. Crossings included 2-lane up to 8-lane roads of varying widths and geometric configurations, with a Theoretical view range of motor vehicle speeds and volumes. The trails varied widely in terms of design and usage, and crossed at various Years of experience, trial and error, and research have led to points (e.g., midblock vs. near a roadway intersection). Also the development of roadway design documents such as the evident was the broad range in the quality of the crossings. MUTCD and the Green Book. While relatively few references Indeed, the junctions varied from the hopelessly uncrossable to are made specifically regarding bicyclists and pedestrians, a “deluxe” signalized situation where there was a median these populations are a part of the traffic stream. Many of the refuge area, elaborate illuminated warning signs, and the trail elements contained in these documents that apply to the safe user was given “hot” button immediate response priority (see movement of motor vehicles may—with modification if page 3-16). In addition, a representative sample of 20 necessary—be