HIGHWAY DESIGN MANUAL 200-1 January 4, 2007

CHAPTER 200 Table 201.1 GEOMETRIC DESIGN AND Sight Distance Standards STRUCTURE STANDARDS Design Speed(1) Stopping(2) Passing (ft) Topic 201 - Sight Distance (mph) (ft) 20 125 800 Index 201.1 - General 25 150 950 Sight distance is the continuous length of highway 30 200 1,100 ahead visible to the driver. Four types of sight 35 250 1,300 distance are considered here: passing, stopping, decision, and corner. Passing sight distance is used 40 300 1,500 where use of an opposing lane can provide passing 45 360 1,650 opportunities (see Index 201.2). Stopping sight 50 430 1,800 distance is the minimum sight distance to be provided on multilane highways and on 2-lane 55 500 1,950 roads when passing sight distance is not 60 580 2,100 economically obtainable. Stopping sight distance also is to be provided for all elements of 65 660 2,300 interchanges and intersections at grade, including 70 750 2,500 private road connections (see Topic 504, Index 75 840 2,600 405.1, & Figure 405.7). Decision sight distance is used at major decision points (see Indexes 201.7 80 930 2,700 and 504.2). Corner sight distance is used at (1) See Topic 101 for selection of design speed. intersections (see Index 405.1, Figure 405.7, and (2) For sustained downgrades, refer to advisory standard in Figure 504.3J). Index 201.3 Table 201.1 shows the standards for stopping The sight distance available for passing at any sight distance related to design speed, and these place is the longest distance at which a driver shall be the minimum values used in design. whose eyes are 3 ½ feet above the pavement Also shown are the values for use in providing surface can see the top of an object 4 ¼ feet high passing sight distance. on the road. See Table 201.1 for the calculated values that are associated with various design Chapter 3 of "A Policy on Geometric Design of speeds. Highways and Streets," AASHTO, contains a thorough discussion of the derivation of stopping In general, 2-lane highways should be designed to sight distance. provide for passing where possible, especially those routes with high volumes of trucks or 201.2 Passing Sight Distance recreational vehicles. Passing should be done on tangent horizontal alignments with constant grades Passing sight distance is the minimum sight or a slight sag vertical curve. Not only are drivers distance required for the driver of one vehicle to reluctant to pass on a long crest vertical curve, but pass another vehicle safely and comfortably. it is impracticable to design crest vertical curves to Passing must be accomplished assuming an provide for passing sight distance because of high oncoming vehicle comes into view and maintains cost where crest cuts are involved. Passing sight the design speed, without reduction, after the distance for crest vertical curves is 7 to 17 times overtaking maneuver is started. longer than the stopping sight distance. Ordinarily, passing sight distance is provided at locations where combinations of alignment and

200-2 HIGHWAY DESIGN MANUAL July 24, 2009 profile do not require the use of crest vertical curves. 201.4 Stopping Sight Distance at Grade Crests Passing sight distance is considered only on 2-lane roads. At critical locations, a stretch of 3- or 4-lane Figure 201.4 shows graphically the relationships passing section with stopping sight distance is between length of crest vertical curve, design sometimes more economical than two lanes with speed, and algebraic difference in grades. Any one passing sight distance. factor can be determined when the other two are known. Passing on sag vertical curves can be accomplished both day and night because headlights can be seen 201.5 Stopping Sight Distance at Grade through the entire curve. Sags See Part 3 of the California Manual on Uniform From the curves in Figure 201.5, the minimum Traffic Control Devices (California MUTCD) for length of vertical curve which provides headlight criteria relating to the placement of barrier striping sight distance in grade sags for a given design for no-passing zones. Note, that the passing sight speed can be obtained. distances shown in the California MUTCD are based on traffic operational criteria. Traffic If headlight sight distance is not obtainable at grade operational criteria are different from the design sags, lighting may be considered. The Design characteristics used to develop the values provided Coordinator and the HQ Traffic Liaison shall be in Table 201.1 and Chapter 3 of AASHTO, A contacted to review proposed grade sag lighting to Policy on Geometric Design of Highways and determine if such use is appropriate. Streets. The aforementioned table and AASHTO reference are also used to design the vertical profile 201.6 Stopping Sight Distance on and horizontal alignment of the highway. Consult Horizontal Curves the Headquarters (HQ) Traffic Liaison when using Where an object off the pavement such as a bridge the California MUTCD criteria for traffic pier, building, cut slope, or natural growth restricts operating-control needs. sight distance, the minimum radius of curvature is Other means for providing passing opportunities, determined by the stopping sight distance. such as climbing lanes or turnouts, are discussed in Available stopping sight distance on horizontal Index 204.5. Chapter 3 of AASHTO, A Policy on curves is obtained from Figure 201.6. It is assumed Geometric Design of Highways and Streets, that the driver's eye is 3 ½ feet above the center of contains a thorough discussion of the derivation of the inside lane (inside with respect to curve) and passing sight distance. the object is ½-foot high. The line of sight is assumed to intercept the view obstruction at the 201.3 Stopping Sight Distance midpoint of the sight line and 2 feet above the The minimum stopping sight distance is the center of the inside lane when the road profile is distance required by the driver of a vehicle, flat (i.e. no vertical curve). Crest vertical curves traveling at a given speed, to bring the vehicle to a can cause additional reductions in sight distance. stop after an object on the road becomes visible. The clear distance (m) is measured from the center Stopping sight distance is measured from the of the inside lane to the obstruction. driver's eyes, which are assumed to be 3 ½ feet The design objective is to determine the required above the pavement surface, to an object ½-foot clear distance from centerline of inside lane to a high on the road. See Index 1003.1(9) for bicycle retaining wall, bridge pier, abutment, cut slope, or stopping sight distance guidance. other obstruction for a given design speed. Using The stopping sight distances in Table 201.1 should radius of curvature and minimum sight distance for be increased by 20 percent on sustained that design speed, Figure 201.6 gives the clear downgrades steeper than 3 percent and longer than distance (m) from centerline of inside lane to the one mile. obstruction.

HIGHWAY DESIGN MANUAL 200-3 July 24, 2009

When the radius of curvature and the clear distance to a fixed obstruction are known, Figure 201.6 also Table 201.7 gives the sight distance for these conditions. Decision Sight Distance See Index 101.1 for technical reductions in design speed caused by partial or momentary horizontal Design Speed Decision Sight sight distance restrictions. See Index 203.2 for (mph) Distance additional comments on glare screens. (ft) Cuts may be widened where vegetation restricting 30 450 horizontal sight distance is expected to grow on 35 525 finished slopes. Widening is an economic trade-off 40 600 that must be evaluated along with other options. See Index 902.2 for sight distance requirements on 45 675 landscape projects. 50 750 201.7 Decision Sight Distance 55 865 At certain locations, sight distance greater than 60 990 stopping sight distance is desirable to allow drivers 65 1,050 time for decisions without making last minute erratic maneuvers (see Chapter III of AASHTO, A 70 1,105 Policy on Geometric Design of Highways and 75 1,180 Streets, for a thorough discussion of the derivation of decision sight distance.) 80 1,260 On freeways and expressways the decision sight distance values in Table 201.7 should be used at lane drops and at off-ramp noses to interchanges, Topic 202 - Superelevation branch connections, roadside rests, vista points, and inspection stations. When determining decision 202.1 Basic Criteria sight distance on horizontal and vertical curves, According to the laws of mechanics, when a Figures 201.4, 201.5, and 201.6 can be used. vehicle travels on a curve it is forced outward by Figure 201.7 is an expanded version of Figure centrifugal force. 201.4 and gives the relationship among length of crest vertical curve, design speed, and algebraic On a superelevated highway, this force is resisted difference in grades for much longer vertical curves by the vehicle weight component parallel to the than Figure 201.4. superelevated surface and side friction between the tires and pavement. It is impractical to balance Decision sight distance is measured using the centrifugal force by superelevation alone, because 3 ½-foot eye height and ½-foot object height. See for any given curve radius a certain superelevation Index 504.2 for sight distance at secondary exits on rate is exactly correct for only one driving speed. a collector-distributor road. At all other speeds there will be a side thrust either outward or inward, relative to the curve center, which must be offset by side friction. If the vehicle is not skidding, these forces are in equilibrium as represented by the following equation, which is used to design a curve for a comfortable operation at a particular speed:

0.067V V 22 fe Factor lCentrifuga Factor fe =+= = R 15R

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Where: whether further adjustments to radius and e = Superelevation slope in feet per superelevation may be needed. foot Except for short radius curves, the standard e = Maximum superelevation rate for max superelevation rate results in very little side thrust a given condition at speeds less than 45 miles per hour. This f = Side friction factor provides maximum comfort for most drivers. R = Curve radius in feet V = Velocity in miles per hour Superelevation for horizontal curves with radii of 10,000 feet and greater may be deleted in those Standard superelevation rates are designed to hold situations where the combination of a flat grade and the portion of the centrifugal force that must be a superelevation transition would create taken up by tire friction within allowable limits. undesirable drainage conditions on the pavement. Friction factors as related to speed are shown on Figure 202.2. The factors apply equally to portland Superelevated cross slopes on curves extend the cement concrete and bituminous pavements. full width of the traveled way and shoulders, except that the shoulder slope on the low side should be 202.2 Standards for Superelevation not less than the minimum shoulder slope used on the tangents (see Index 304.3 for cross slopes under Maximum superelevation rates for various highway cut widening conditions). conditions are shown on Table 202.2. On rural 2-lane roads, superelevation should be on Based on an emax selected by the designer for the same plane for the full width of traveled way one of the conditions, superelevation rates from and shoulders, except on transitions (see Index Table 202.2 shall be used within the given range 304.3 for cut widening conditions). of curve radii. If less than standard supereleva- tion rates are approved (see Index 82.1), Figure 202.3 Restrictive Conditions 202.2 shall be used to determine superelevation based on the curve radius and maximum Lower superelevation rates than those given in comfortable speed. either Table 202.2 or Figure 202.2 may be necessary in areas where restricted speed zones or Maximum comfortable speed is determined by the ramp/street intersections are controlling factors. formula given on Figure 202.2. It represents the Other typical locations are short radius curves on speed on a curve where discomfort caused by ramps near the local road juncture, either at an centrifugal force is evident to a driver. Side intersection or where a loop connects with an friction factors tabulated on Figure 202.2 are overcrossing structure. Often, established street recommended by AASHTO for design purposes. grades, curbs, or drainage may prove difficult to AASHTO, A Policy on Geometric Design of alter and/or superelevation transition lengths would Highways and Streets, states, "In general, studies be undesirably short. show that the maximum side friction factors developed between new tires and wet concrete Such conditions may justify a reduction in the pavements range from about 0.5 at 20 mph to superelevation rate, different rates for each half of approximately 0.35 at 60 mph." The design side the roadbed, or both. In any case, the friction factors are, therefore, about one-third the superelevation rate provided should be appropriate values that occur when side skidding is imminent. for the conditions allowing for a smooth transition while providing the maximum level of comfort to To use Figure 202.2, the designer must decide on the driver. Where standard superelevation rates the relative importance among three variables. cannot be attained, discussions should be held with Normally, when a nonstandard superelevation rate the Design Reviewer and/or the Design is approved, Figure 202.2 will be entered with the Coordinator to determine the proper solution and rate and a desired curve radius. It must then be the necessity of preparing a design exception fact determined whether the resulting maximum sheet. In warping street or ramp surface areas for comfortable speed is adequate for the conditions or

HIGHWAY DESIGN MANUAL 200-5 October 4, 2010

Figure 201.4 Stopping Sight Distance on Crest Vertical Curves

L = Curve Length (feet)

A = Algebraic Grade Difference (%)

S = Sight Distance (feet)

V = Design Speed for “S” in mph

K = Distance in feet required to achieve Drivers eye height is 3 ½ feet. a 1% change in grade. K value as Object height is ½-foot. shown on graph is valid when S < L. Notes: • Before using this figure for intersections, branch connections and exits, see Indexes 201.7 and 405.1, and Topic 504. • See Figure 204.4 for vertical curve formulas. • See Index 204.4 for minimum length of vertical curve When S > L When S < L

L = 2S – 1329/A L = AS2 /1329

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Figure 201.5 Stopping Sight Distance on Sag Vertical Curves

L = Curve Length (feet) A = Algebraic Grade Difference (%) S = Sight Distance (feet) V = Design Speed for “S” in mph K = Distance in feet required to achieve a 1% change in grade. K value as shown on graph is valid when S < L.

Notes: • For sustained downgrades, see Index 201.3. • Before using this figure for intersections, branch connections and exits, see Indexes 201.7 and 405.1, and Topic 504. • See Figure 204.4 for vertical curve formulas. • See Index 204.4 for minimum length of vertical curve.

When S > L When S < L

L = 2S - (400 + 3.5S)/A L = AS2 /(400 + 3.5S)

HIGHWAY DESIGN MANUAL 200-7 October 4, 2010

Figure 201.6 Stopping Sight Distance on Horizontal Curves

Line of sight is 2.0 feet above the centerline inside lane at point of obstruction. R = Radius of the centerline of the lane nearest the obstruction (feet). S = Sight Distance (feet) V = Design Speed for “S” in mph m = Clear distance from centerline of the lane nearest the obstruction (feet).

Notes: ⎡ ⎛ 28.65S ⎞⎤ • For sustained downgrades, see Index 201.3. m = ⎢ COS-1R ⎜ ⎟⎥ • Formulas apply only when “S” is equal to or less than length of ⎣ ⎝ R ⎠⎦ curve. R ⎡ 1- ⎛ -R m ⎞⎤ • Angles in formulas are expressed in degrees. S = ⎢COS ⎜ ⎟⎥ 28.65 ⎣ ⎝ R ⎠⎦

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Figure 201.7 Decision Sight Distance on Crest Vertical Curves

L = Curve Length (feet)

A = Algebraic Grade Difference (%)

S = Sight Distance (feet)

V = Design Speed for “S” in mph

K = Distance in feet required to achieve a 1% Drivers eye height is 3½ feet. change in grade. K value as shown on Object height is ½-foot. graph is valid when S < L.

Notes: • Before using this figure for intersections, branch connections and exits, see Indexes 201.7 and 405.1, and Topic 504. • See Figure 204.4 for vertical curve formulas. • See Index 204.4 for minimum length of vertical curve.

When S > L When S < L

L = 2S – 1329/A L = AS2 /1329

HIGHWAY DESIGN MANUAL 200-9 September 1, 2006 drainage, adverse superelevation should be avoided Aesthetics, grade distortion, superelevation (see Figure 202.2). transitions, drainage, and driver perception should be considered when selecting the axis 202.4 Axis of Rotation of rotation (see Index 204.2). (1) Undivided Highways. For undivided highways the axis of rotation for superelevation is 202.5 Superelevation Transition usually the centerline of the roadbed. (1) General. The superelevation transition However, in special cases such as desert roads generally consists of the crown runoff and the where curves are preceded by long relatively superelevation runoff as shown on Figure level tangents, the plane of superelevation may 202.5A and 202.5B. be rotated about the inside edge of traveled A superelevation transition should be designed way to improve perception of the curve. In flat in accordance with the diagram and tabular country, drainage pockets caused by data shown in Figure 202.5A to satisfy the superelevation may be avoided by changing requirements of safety, comfort and pleasing the axis of rotation from the centerline to the appearance. The length of superelevation inside edge of traveled way. transition should be based upon the (2) Ramps and Freeway-to-freeway Connections. combination of superelevation rate and width The axis of rotation may be about either edge of rotated plane in accordance with the of traveled way or centerline if multilane. tabulated superelevation runoff lengths on the Appearance and drainage considerations bottom of Figure 202.5A. should always be taken into account in Edge of traveled way and shoulder profiles selection of the axis of rotation. should be plotted and irregularities resulting (3) Divided Highways. from interactions between the superelevation transition and vertical alignment of the (a) Freeways--Where the initial median width roadway should be eliminated by introducing is 65 feet or less, the axis of rotation smooth curves. Edge of traveled way and should be at the centerline. shoulder profiles also will reveal flat areas Where the initial median width is greater which are undesirable from a drainage than 65 feet and the ultimate median width standpoint and should be avoided. is 65 feet or less, the axis of rotation (2) Runoff. Two-thirds of the superelevation should be at the centerline, except where runoff should be on the tangent and one-third the resulting initial median slope would be within the curve. This results in two-thirds of steeper than 10:1. In the latter case, the the full superelevation rate at the beginning or axis of rotation should be at the ultimate ending of a curve. This may be altered as median edges of traveled way. required to adjust for flat spots or unsightly Where the ultimate median width is greater sags and humps, or when conforming to than 65 feet, the axis of rotation should existing roadway. normally be at the ultimate median edges (3) Restrictive Situations. In restrictive situations, of traveled way. such as on two lane highways in mountainous To avoid sawtooth on bridges with decked terrain, interchange ramps, collector roads, medians, the axis of rotation, if not already frontage roads, etc., where curve radius and on centerline, should be shifted to the length and tangents between curves are short, centerline. standard superelevation rates and/or transitions (b) Conventional Highways--The axis of may not be attainable. In such situations the rotation should be considered on an highest possible superelevation rate(s) and individual project basis and the most transition length should be used, but the rate of appropriate case for the conditions should change of cross slope should not exceed be selected. 6 percent per 100 feet.

200-10 HIGHWAY DESIGN MANUAL September 1, 2006

Table 202.2

Standard Superelevation Rates (Superelevation in Feet per Foot for Curve Radius in Feet)

Ramps, Freeways, When Snow & Ice Urban Roads Urban Roads 2-Lane Conventional Expressways, Conditions Prevail (35 – 45 mph) (less than 35 mph) Highways, Frontage Multilane Conventional (Usually over 3,000 ft Roads(1) Highways elevation)

For e = 0.12 For e = 0.10 For e = 0.08 For e = 0.06 For e = 0.04 max max max max max

Range of e Range of e Range of e Range of e Range of e Curve Radii Rate Curve Radii Rate Curve Radii Rate Curve Radii Rate Curve Radii Rate Under 625 0.12 625 – 849 0.11 850 – 1,099 0.10 Under 1,100 0.10 1,100 – 1,349 0.09 1,100 – 1,349 0.09 1,350 – 1,599 0.08 1,350 – 1,599 0.08 Under 1,600 0.08 1,600 – 1,899 0.07 1,600 – 1,899 0.07 1,600 – 1,899 0.07 1,900 – 2,199 0.06 1,900 – 2,199 0.06 1,900 – 2,199 0.06 Under 600 0.06 2,200 – 2,699 0.05 2,200 – 2,699 0.05 2,200 – 2,699 0.05 600 – 999 0.05 2,700 – 3,499 0.04 2,700 – 3,499 0.04 2,700 – 3,499 0.04 1,000 – 1,499 0.04 Under 500 0.04 3,500 – 4,499 0.03 3,500 – 4,499 0.03 3,500 – 4,499 0.03 1,500 – 1,999 0.03 500 – 999 0.03 4,500 – 19,999 0.02 4,500 – 19,999 0.02 4,500 – 19,999 0.02 2,000 – 6,999 0.02 1,000 – 4,999 0.02 20,000 & over (2) 20,000 & over (2) 20,000 & over (2) 7,000 & over (2) 5,000 & over (2) Notes:

(1) For frontage roads under other jurisdictions see Index 202.7. (2) Use standard crown section.

HIGHWAY DESIGN MANUAL 200-11 July 24, 2009

Figure 202.2 Maximum Comfortable Speed on Horizontal Curves

Speed Side Friction (mph) Factor “f” 20 0.17 NOTES: 30 0.16 This figure is not intended to represent standard 40 0.15 superelevation rates or curve radius. The standards are 50 0.14 contained in Tables 202.2 and 203.2. This figure should be used as an aid to designers to determine 55 0.13 maximum comfortable speeds. Use of this figure in 60 0.12 lieu of the standards must be documented as discussed 65 0.11 in Index 82.2. 70 0.10 e - Superelevation 75 0.09 f - Side Friction Factor 0.067V 2 80 0.08 V - Speed (mph) fe =+ R R - Radius (feet)

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(4) Superelevation Transitions on Bridges. the connection is to a non-controlled access Superelevation transitions on bridges should facility (conventional highway), AASHTO be avoided whenever possible (See Index standards shall prevail. If the local agency 203.9). having jurisdiction over the local facility in (5) Shoulder Transitions. The shoulder plane question maintains standards that exceed AASHTO rotates about the adjacent edge of traveled standards, then the local agency standards should way as well as the rotational axis of the prevail. traveled way. Shoulder superelevation The major considerations in horizontal alignment transitions should be smooth and compatible design are safety, profile, type of facility, design with the transition of the adjacent pavements. speed, geotechnical features, topography, right of way cost and construction cost. In design, safety is 202.6 Superelevation of Compound Curves always considered, either directly or indirectly. On freeways in metropolitan areas, alternative studies Superelevation of compound curves should follow often indicate that right of way considerations the procedure as shown in Figure 202.6. Where influence alignment more than any other single feasible, the criteria in Index 202.5 should apply. factor. Topography controls both curve radius and design speed to a large extent. The design speed, in 202.7 Superelevation on City Streets and turn, controls sight distance, but sight distance must County Roads be considered concurrently with topography Superelevation rates of local streets and roads because it often demands a larger radius than the which are within the State right of way (with or design speed. All these factors must be balanced to without connection to State facilities) shall produce an alignment which optimizes the conform to AASHTO standards, for the achievement of various objectives such as safety, functional classification of the facility in cost, harmony with the natural contour of the land, question. If the local agency having jurisdiction and at the same time adequate for the design over the local facility in question maintains classification of the highway. standards that exceed AASHTO standards, then the Horizontal alignment shall provide at least the local agency standards should prevail. minimum stopping sight distance for the chosen See Index 202.2 and Table 202.2 for Frontage design speed at all points on the highway, as Roads within the State right of way. Frontage given in Table 201.1 and explained in Index roads that will be relinquished after construction 201.3. See Index 101.1 for technical reductions in should follow AASHTO or local standards as design speed. stated above. 203.2 Standards for Curvature Topic 203 - Horizontal Alignment Table 203.2 shall be the minimum radius of curve for specific design speeds. This table is 203.1 General Controls based upon speed alone; it ignores the sight distance factor. If the minimum radius indicated Horizontal alignment should provide for safe and in Table 203.2 does not provide the desired continuous operation at a uniform design speed for lateral clearance to an obstruction, Figure 201.6 substantial lengths of highway. The standards shall govern. which follow apply to curvature on both 2-lane and multilane highways except when otherwise noted. These standards also apply to portions of local streets and roads within the State right of way which connect directly to a freeway or expressway, or are expected to do so in the foreseeable future. For local facilities which are within the State right of way and where there is no connection or

HIGHWAY DESIGN MANUAL 200-13 July 24, 2009

Figure 202.5A Superelevation Transition

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Figure 202.5B Superelevation Transition Terms & Definitions Term Definition

Crown Runoff The distance from the station where the high side of the superelevating section surfaces are at a cross slope of 2% to where the high side of the section surfaces 2 3 reaches a cross slope of 0%.

Superelevation The distance from the station where the high side of the superelevating section Runoff(L) surfaces are at a cross slope of 0% to the station where the entire cross section is at full superelevation. 3 6 Superelevation The distance from the station where the high side of the superelevating sections are Transition crowned at a cross slope of 2% to the station where the entire cross section is at full superelevation. The Crown Runoff Length plus the Superelevation Runoff Length (L) 2 6 equals the Superelevation Transition Length.

% On tangent The percentage of the superelevation runoff length (L) that is outside of the curve (2/3L). See Index 202.5(2).

% On curve The percentage of the superelevation runoff length (L) that is within the curve (1/3L). See Index 202.5(2). The % On Tangent and % On curve values must total 100%.

Elements of a Superelevation Transition (Right Curve)

HIGHWAY DESIGN MANUAL 200-15 September 1, 2006

Figure 202.6

Superelevation of Compound Curves

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Every effort should be made to exceed minimum more than 10 miles per hour. Introduction of curves values, and such minimum radii should be used only with lower design speeds should be avoided at the when the cost or other adverse effects of realizing a end of long tangents, steep downgrades, or at other higher standard are inconsistent with the benefits. locations where high approach speeds may be As an aid to designers, Figure 202.2 displays the anticipated. maximum comfortable speed for various curve radii The horizontal and vertical alignments should be and superelevation rates. Use of Figure 202.2, in coordinated such that horizontal curves are not lieu of the above standards must be documented as hidden behind crest vertical curves. Sharp discussed in Index 82.2. horizontal curves should not follow long tangents The recommended minimum radii for freeways are because some drivers tend to develop higher speeds 5,000 feet in rural areas and 3,000 feet in urban on the tangent and could over drive the curve. areas. See “Combination of Horizontal and Vertical If a glare screen or a median barrier is contemplated, Alignment” in Chapter III of AASHTO, A Policy on either initially or ultimately, adjustments may be Geometric Design of Highways and Streets, for necessary to maintain the required sight distance on further guidance on alignment consistency. curves on divided highways. In such cases, a larger curve radius or a wider median may be required 203.4 Curve Length and Central Angle throughout the length of the curve. For design The minimum curve length for central angles less purposes, a planting screen is presumed to be 8 feet than 10 degrees should be 800 feet to avoid the wide. See Chapter 7 of the Traffic Manual for glare appearance of a kink. For central angles smaller screen criteria. than 30 minutes, no curve is required. Above a 20,000 -foot radius, a parabolic curve may be used. Table 203.2 In no event should sight distance or other safety considerations be sacrificed to meet the above Standards for Curve Radius requirements. Design Speed Minimum Radius On 2-lane roads a curve should not exceed a length mph of Curve (ft) of one-half mile and should be no shorter than 500 feet. 20 130 30 300 203.5 Compound Curves 40 550 Compound curves should be avoided because drivers who have adjusted to the first curve could 50 850 over drive the second curve if the second curve has 60 1,150 a smaller radius than the first. Exceptions can occur 70 2,100 in mountainous terrain or other situations where use 80 3,900 of a simple curve would result in excessive cost. Where compound curve is necessary, the shorter radius should be at least two-thirds the longer radius when the shorter radius is 1,000 feet or less. On one-way roads, the larger radius should follow the 203.3 Alignment Consistency smaller radius. Sudden reductions in alignment standards should be The total arc length of a compound curve should be avoided. Where physical restrictions on curve not less than 500 feet. radius cannot be overcome and it becomes necessary to introduce curvature of lower standard than the design speed for the project, the design speed between successive curves should change not

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All portions of the grade line must meet sight 203.6 Reversing Curves distance requirements for the design speed When horizontal curves reverse direction the classification of the road. connecting tangents should be long enough to In flat terrain, the elevation of the grade line is often accommodate the standard superelevation runoffs controlled by drainage considerations. In rolling given on Figure 202.5. If this is not possible, the terrain, some undulation in the grade line is often 6 percent per 100 feet rate of change should govern advantageous for construction economy. This (see Index 202.5(3)). When feasible, a minimum of should be done with appearance in mind; for 400 feet of tangent should be considered. example, a grade line on tangent alignment exhibiting a series of humps visible for some 203.7 Broken Back Curves distance ahead should be avoided whenever A broken back curve consists of two curves in the possible. In rolling hills or mountainous terrain, same direction joined by a short tangent. Broken however, the grade line usually is more closely back curves are unsightly and undesirable. dependent upon physical controls. In considering alternative profiles, economic 203.8 Spiral Transition comparisons involving earthwork quantities and/or Spiral transition curves are not standard practice. retaining walls should be made. A balanced earthwork design is most cost effective. When long 203.9 Alignment at Bridges or steep grades are involved, economic comparisons should include vehicle operating costs. Due to the difficulty in constructing bridges with superelevation rates greater than 10 percent, the The standards in Topic 204 also apply to portions of curve radii on bridges should be designed to local streets and roads within the State right of way accommodate superelevation rates of 10 percent or which connect directly to a freeway or expressway, less. See Index 202.2 for standard superelevation or are expected to do so in the foreseeable future. rates. For local facilities which are within the State right of way and where there is no connection or Superelevation transitions on bridges are difficult to the connection is to a non-controlled access construct and almost always result in an unsightly facility (conventional highway), AASHTO appearance of the bridge and the bridge railing. standards shall prevail. If the local agency having Therefore, if possible, horizontal curves should jurisdiction over the local facility in question begin and end a sufficient distance from the bridge maintains standards that exceed AASHTO so that no part of the superelevation transition standards, then the local agency standards should extends onto the bridge. prevail. Alignment and safety considerations, however, are paramount and must not be sacrificed to meet the 204.2 Position With Respect to Cross Section above criteria. The grade line should generally coincide with the axis of rotation for superelevation (see Index Topic 204 - Grade 202.4). Its relation to the cross section should be as follows: 204.1 General Controls (1) Undivided Highways. The grade line should The grade line is a reference line by which the coincide with the highway centerline. elevation of the pavement and other features of the (2) Ramps and Freeway-to-freeway Connections. highway are established. It is controlled mainly by Although the grade line is usually positioned at topography, type of highway, horizontal alignment, the left edge of traveled way, either edge of performance of heavy vehicles, right of way costs, traveled way or centerline may be used on safety, sight distance, construction costs, cultural multilane facilities. development, drainage, and pleasing appearance.

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(3) Divided Highways. The grade line should be Ramp grades should not exceed 8 percent. On positioned at the centerline of the median for descending on-ramps and ascending off-ramps, one paved medians 65 feet wide or less, thus percent steeper is allowed (see Index 504.2(5)). avoiding a “saw tooth” section, which can reduce horizontal stopping sight distance. 204.4 Vertical Curves The grade line may be positioned at the Properly designed vertical curves should provide ultimate median edge of traveled way when: adequate sight distance, safety, comfortable driving, good drainage, and pleasing appearance. (a) The median edges of traveled way of the two roadways are at equal elevation. A parabolic vertical curve is used. Figure 204.4 gives all necessary mathematical relations for (b) The two roadways are at different computing a vertical curve, either at crests or sags. elevations as described in Index 204.8. For algebraic grade differences of 2 percent and (c) The width of median is nonuniform (see greater, and design speeds equal to or greater than Index 305.6). 40 miles per hour, the minimum length of vertical curve in feet should be equal to 10V, where V = 204.3 Standards for Grade design speed. As an example, a 65 miles per hour design speed would require a 650-foot minimum Table 204.3 shows the maximum grades which vertical curve length. For algebraic grade shall not be exceeded for the condition indicated. differences of less than 2 percent, or design speeds Steep grades affect truck speeds and overall less than 40 miles per hour, the vertical curve length capacity. They also cause operational problems at should be a minimum of 200 feet. Vertical curves intersections. For these reasons it is desirable to are not required where the algebraic difference in provide the flattest grades practicable (see Index grades is 0.5 percent or less. Grade breaks should 204.5 for information on truck issues with grades). not be closer together than 50 feet and a total of all grade breaks within 200 feet should not exceed Table 204.3 0.5 percent. Since flat vertical curves may develop poor drainage Maximum Grades for Type of at the level section, adjusting the gutter grade or Highway and Terrain Conditions shortening the vertical curve may overcome any drainage problems. Type of Freeways and Rural Urban On 2-lane roads, extremely long crest vertical Terrain Expressways Highways Highways curves, over one-half mile, should be avoided, since Level 3% 4% 6% many drivers refuse to pass on such curves despite Rolling 4% 5% 7% adequate sight distance. It is sometimes more economical to construct passing lanes than to obtain Mountainous 6% 7% 9% passing sight distance by the use of a long vertical curve. Minimum grades should be 0.5 percent in snow Broken-back vertical curves consist of two vertical country and 0.3 percent at other locations. Except curves in the same direction separated by a short for conventional highways in urban or suburban grade tangent. A profile with such curvature areas, a level grade line is permissible in level normally should be avoided, particularly in sags terrain where side fill slopes are 4:1 or flatter and where the view of both curves is not pleasing. dikes are not needed to carry water in the roadbed. Flat grades are not permissible in superelevation transitions due to flat spots which cause ponding on the roadbed.

HIGHWAY DESIGN MANUAL 200-19 September 1, 2006

Figure 204.4 Vertical Curves

200-20 HIGHWAY DESIGN MANUAL September 1, 2006

the ADT exceeds 5000, 4-lane passing 204.5 Sustained Grades sections may be considered. See Index (1) General. Maximum grade is not a complete 305.1(2) for median width standards. design control. The length of an uphill grade The Headquarters Division of Traffic is important as well, because it affects Operations should be consulted regarding the capacity, level of service, and delay when length of climbing and passing lanes, which slow moving trucks, buses, and recreational will vary with the design speed of the vehicles are present. highway, the traffic volume, and other factors. A common criterion for all types of highways (4) Turnouts is to consider the addition of a climbing lane where the running speed of trucks falls (a) General. On a two-lane highway where 10 miles per hour or more below the running passing is limited, Section 21656 of the speed of remaining traffic. Figure 204.5 California Vehicle Code requires slow- shows the speed reduction curves for a moving vehicles followed by five or more 200 lb/hp truck, which is representative of vehicles to turn off at designated turnouts large trucks operating near maximum gross or wherever sufficient area for a safe weight. The 10 miles per hour reduction turnout exists. Designated turnouts may criterion may be used as one method of be constructed in hilly or mountainous determining need, however the Highway terrain or on winding roads in other areas. Capacity Manual should be consulted for (b) Length. Designated turnouts should be detailed analysis. from 200 feet to 500 feet long including a (2) Freeway Climbing Lanes. If design year short taper (usually 50 feet) at each end. traffic volumes are expected to be near Approach speeds, grades, traffic volumes, capacity, right of way acquisition and grading and available space are some factors to be for a future lane should be considered at considered in determining the length. The locations where the upgrade exceeds 2 percent Headquarters Traffic Liaison should be and the total rise exceeds 50 feet. consulted if longer turnouts are desired. Regardless of traffic volumes, the need for a (c) Width. Paved widths of at least 15 feet in climbing lane should be investigated on fill sections and 12 feet in cut sections are sustained upgrades greater than 2 percent if recommended. Width is measured from the total rise is greater than 250 feet. Refer to the edge of traveled way. On the outside the Highway Capacity Manual for passenger of curves along steep fill slopes or car equivalent factors and sample calculations. dropoffs, greater width or the installation of guardrail should be considered. Decision sight distance (Table 201.7) should be provided at climbing lane drops on (d) Location. Turnouts should be located freeways. where there is stopping sight distance for approaching drivers to see vehicles (3) Two-lane Road Climbing and Passing Lanes. leaving and re-entering the through lanes. Climbing and passing lanes are most effective on uphill grades and curving alignment where the speed differential among vehicles is significant. Climbing and passing lanes should normally not be constructed on tangent sections where the length of tangent equals or exceeds the passing sight distance, because passing will occur at such locations without a passing lane and the double barrier stripe increases delay for opposing traffic. Where

HIGHWAY DESIGN MANUAL 200-21 September 1, 2006

Figure 204.5

Critical Lengths of Grade for Design

ASSUMED TYPICAL HEAVY TRUCK

OF 200 lb/hp

200-22 HIGHWAY DESIGN MANUAL September 1, 2006

differences between opposing grade lines in special 204.6 Coordination of Horizontal and situations. Vertical Alignment In addition, for either interim or ultimate A proper balance between curvature and grades expressways, any appreciable grade differential should be sought. When possible, vertical curves between roadbeds should be avoided in the vicinity should be superimposed on horizontal curves. This of at-grade intersections. For traffic entering from reduces the number of sight restrictions on the the crossroad, confusion and wrong-way project, makes changes in profile less apparent, movements could result if the pavement of the far particularly in rolling country, and results in a roadway is obscured because of excessive grade pleasing appearance. Where the change in differential. horizontal alignment at a grade summit is moderate, a pleasing appearance may be attained 204.8 Grade Line of Structures by making the vertical curve overlap the horizontal (1) Structure Depth. The depth to span ratio for curve. each structure is dependent on many factors. When horizontal and vertical curves are Some of these are: span, type of construction, superimposed, the combination of superelevation aesthetics, cost, falsework limitations, and and profile grades may cause distortion in the outer vertical clearance limitations. For purposes of pavement edges which could create drainage preliminary planning and design, the depth to concerns or confuse drivers at night. In such span ratios listed below may be used in setting situations edge of pavement profiles should be grade lines at grade separations. plotted and smooth curves introduced to eliminate (a) Railroad Underpass Structures. any irregularities or distortion. • Single track, through girder type On highways in mountainous or rolling terrain structures: use 5-foot depth from top of where horizontal and vertical curves are rail to structure soffit (bottom of superimposed at a grade summit or sag, the design girder). speed of the horizontal curve should be at least equal to that of the crest or sag, and not more than • Deck-type structures: for simple spans 10 miles per hour less than the measured or use d/s (depth to span ratio)= 0.08; for estimated running (85th percentile) speed of continuous multiple span structures use vehicles on the approach roadway. d/s= 0.07. These ratios do not include the additional 2 feet required above the On long open curves, a uniform grade line should deck for ballast and rail height. be used because a rolling profile makes for a poor appearance. (b) Highway Structures. Horizontal and vertical curvature at intersections • Structures with single spans of 100 feet should be as flat as physical conditions permit. or less, use d/s= 0.06. See “Combination of Horizontal and Vertical • Structures with single spans between Alignment” in Chapter III of AASHTO, A Policy 100 feet and 180 feet use d/s= 0.045. on Geometric Design of Highways and Streets, for • Continuous structures with multiple further guidance on a alignment consistency. spans of 100 feet or less, use d/s= 0.055. 204.7 Separate Grade Lines • Continuous structures with multiple Separate or independent grade lines are appropriate spans of more than 100 feet, use in some cases for freeways and expressways. d/s= 0.04. They are not normally considered appropriate where medians are less than 65 feet wide (see Index 305.6). Exceptions to this may be minor

HIGHWAY DESIGN MANUAL 200-23 September 1, 2006

Table 204.8

Falsework Span and Depth Requirements

Depth of Superstructure(4) Minimum Up to Up to Up to Up to Normal Resulting 6 feet 8 feet 10 feet 12 feet Width of Falsework Facility to Traffic Opening Width Normal Minimum Falsework Depth be Spanned Opening Provides for Span(1)

Freeway 25' 1 Lane + 8' & 5' Shoulders 33' 1'-10½" 2'-1' 2'-1' 2'-8½" 37' 2 Lanes + 8' & 5' Shoulders 45' 2'-9" 2'-11½" 3'-0" 3'-3" 49' 3 Lanes + 8' & 5' Shoulders 57' 3'-3" 3'-3½" 3'-3½" 3'-3½" 61' 4 Lanes + 8' & 5' Shoulders 69' 3'-4" 3'-5" 3'-7" 3'-7½" Nonfreeway 20' 1 Lane + 2-4' Shoulders 28' 1'-9" 1'-10" 1'-10" 1'-10½" 32' 2 Lanes + 2-4' Shoulders 40' 2'-0" 2'-8½" 2'-9" 3'-0" 40' 2 Lanes + 2-8' Shoulders 48' 3'-0" 3'-0" 3'-2½" 3'-3" 52' 3 Lanes + 2-8' Shoulders 60' 3'-3" 3'-3½" 3'-3½" 3'-4" 64' 4 Lanes + 2-8' Shoulders 72' 3'-5" 3'-7½" 3'-7½" 3'-8" Special 20' 1 Lane + 2-4' Shoulders 20' (3) 1'-9" 1'-10" 1'-10" 1'-10½" (2) Roadways 32' 2 Lanes + 2-4' Shoulders 32' (3) 2'-0" 2'-8½" 2'-9" 3'-0" Notes: (1) Includes 8' for 2 temporary K-rails and deflection space. (2) Uses such as fire or utility access or quasi-public roads with very light traffic. (3) No temporary K-rail provided. (4) See Index 204.8 for preliminary depth to span ratios. For more detailed information, contact the Division of Engineering Services, Structure Design and refer to the Bridge Design Aids.

Geometric plans should be submitted to the permit lower grade lines and reduced DOS prior to preparation of the Project approach fill heights. Potential cost savings Report so that preliminary studies can be from elimination of falsework, lowered grade prepared. Preliminary bridge type selection lines, and the ability to accomodate settlement should be a joint effort between the DOS and beneath the abutments should be considered in the District. structure type selection along with unit price, aesthetics, uniformity, and any other relevant (2) Steel or Precast Concrete Structures. Steel factors. Note that grade lines at grade and precast concrete girders in lieu of cast-in- separations frequently need to be adjusted place concrete eliminate falsework, and may after final structure depths are determined (see

200-24 HIGHWAY DESIGN MANUAL October 4, 2010

Index 309.2(3)). Details of traffic handling In special cases, where existing constraints and stage construction should be provided make it impractical to comply with the when the bridge site plan is submitted to the minimum widths of traffic openings set forth DOS if the design or construction of the in Table 204.8, a lesser width may be structure is affected (see Drafting and Plans approved by the District Director with Manual, Section 3-3.2). concurrence from the Headquarters Design Coordinator. (3) Depressed Grade Line Under Structures. Bridge and drainage design will frequently be The minimum vertical falsework clearance simplified if the low point in the grade line is over freeways and nonfreeways shall be set a sufficient distance from the intersection 15 feet. The following items should be of the centerlines of the structure and the considered: highway so that drainage structures clear the • Mix, volume, and speed of traffic. structure footings. • Effect of increased vertical clearance (4) Grade Line on Bridge Decks. Vertical curves on the grade of adjacent sections. on bridge decks should provide a minimum fall of 0.05-foot per station. This fall should • Closing local streets to all traffic or not extend over a length greater than 100 feet. trucks only during construction. The flattest allowable tangent grade should be • Detours. 0.3 percent. • Carrying local traffic through (5) Falsework. In many cases, it is economically construction on subgrade. justified to have falsework over traffic during construction in order to have a support-free • Temporary or permanent lowering of open area beneath the permanent structure. the existing facility. The elimination of permanent obstructions • Cost of higher clearance versus cost of usually outweighs objections to the temporary traffic control. inconvenience of falsework during construction. • Desires of local agency. Because the width of traffic openings through Worker safety should be considered when falsework can, and oftentimes does, determining vertical falsework clearance. significantly affect costs, special care should Requests for approval of temporary vertical be given to determining opening widths. The clearances less than 15 feet should discuss the following should be considered: staging and impact on worker safety. traffic handling requirements, the width of Temporary horizontal clearances less than approach roadbed that will exist at the time shown in Table 204.8 or temporary vertical the bridge is constructed, traffic volumes, clearances less than 15 feet should be noted in desires of the local agencies, controls in the the PS&E Transmittal Report. form of existing facilities, and the practical problems of falsework construction. To establish the grade of a structure to be constructed with a falsework opening, The normal minimum width of traffic allowance must be made for the depth of the openings and required falsework spans for falsework. The minimum depths required for various lane and shoulder combinations various widths of traffic opening are shown in should be as shown in Table 204.8. Table 204.8. When temporary K-rail is used to protect the Where vertical clearances, either temporary or falsework, space must be provided for its permanent are critical, the District and the deflection. The normal spans shown in Table DOS should work in close conjunction during 204.8 provide 2 feet for this deflection. the early design stage when the preliminary

HIGHWAY DESIGN MANUAL 200-25 October 4, 2010

grades, structure depths, and falsework depths can be adjusted without incurring major Topic 205 - Road Connections design changes. and Driveways Where the vertical falsework clearance is less than 15 feet, advance warning devices are to 205.1 Access Openings on Expressways be specified or shown on the plans. Such devices may consist of flashing lights, Access openings are used only on expressways. overhead signs, over-height detectors, or a The term access opening applies to openings combination of these or other devices. through the right of way line which serve abutting land ownerships whose remaining access rights Warning signs on the cross road or in advance have been acquired by the State. of the previous off-ramp may be required for overheight permit loads. Check with the (1) Criteria for Location. Access openings Regional Permit Manager. should not be spaced closer than one-half mile to an adjacent public road intersection or to After establishing the opening requirements, a another private access opening that is wider field review of the bridge site should be made than 30 feet. When several access openings by the District designer to ensure that existing are closely spaced, a frontage road should be facilities (drainage, other bridges, or road- considered (see Index 104.3). To discourage ways) will not conflict with the falsework. wrong-way movements, access openings The placement and removal of falsework should be located directly opposite, or at least requires special consideration. During these 300 feet from a median opening. operations, traffic should either be stopped for Sight distance equivalent to that required short intervals or diverted away from the span for public road intersections shall be where the placement or removal operations provided (see Index 405.1). are being performed. The method of traffic handling during these operations is to be (2) Width. The normal access opening width included in the Special Provisions. should be 30 feet. A greater width may result in large savings in right of way costs in some instances, but should be considered with caution because of the possibility that public use might develop. Conversion of a private opening into a public road connection requires the consent of the CTC, which cannot be committed in advance (see the Project Development Procedures Manual). (3) Recessed Access Openings. Recessed access openings, as shown on Figure 205.1, are desirable at all points where private access is permitted and should be provided whenever they can be obtained without requiring alterations to existing adjacent improvements. When recessed openings are required, the opening should be located a minimum distance of 75 feet from the nearest edge of the traveled way. (4) Joint Openings. A joint access opening serving two or more parcels of land is desirable whenever feasible. If the property

200-26 HIGHWAY DESIGN MANUAL July 24, 2009

line is not normal to the right of way line, care are not applied to urban driveways. See Index should be taken in designing the joint opening 405.1(2) for further information. so that both owners are adequately served. (1) Correlation with Local Standards. Where (5) Surfacing. All points of private access should there is a local requirement regulating be surfaced with adequate width and depth of driveway construction, the higher standard pavement to serve the anticipated traffic. The will normally govern. surfacing should extend from the edge of the (2) Driveway Width. The width of driveways for traveled way to the right of way line. both residential and commercial usage is measured at the throat, exclusive of any flares. Figure 205.1 (“W” as shown in Standard Plan A87A).

Access Openings on (3) Residential Driveways. The width of single Expressways residential driveways should be 12 feet minimum and 20 feet maximum. The width of a double residential driveway such as used for multiple dwellings should be 20 feet minimum and 30 feet maximum. The width selected should be based on an analysis of the anticipated volume, type and speed of traffic, location of buildings and garages, width of street, etc. (4) Commercial Driveways. Commercial driveways should be limited to the following RECESSED OPENING maximum widths: NOTES: (a) When the driveway is used for one-way traffic, the maximum width should be • By widening the expressway shoulder, 25 feet. If the driveway serves a large deceleration lanes may be provided where parcel, where large volumes of vehicles or justified. large vehicles are expected, the entrance • This detail, without the recess, may be used on maximum width should be 40 feet and the conventional highways. exit maximum width should be 35 feet. (b) When the driveway is used for two-way 205.2 Private Road Connections traffic, the maximum width should be The minimum private road connection design is 35 feet. If the driveway serves a large shown on Figure 205.1. Sight distance parcel, where large volumes of vehicles or requirements for the minimum private road large vehicles are expected, then the connection are shown on Figure 405.7 (see Index maximum width should be 45 feet. 405.1(2)(c)). (c) When only one driveway serves a given 205.3 Urban Driveways property, in no case should the width of the driveway including the side slope These instructions apply to the design of driveways distances exceed the property frontage. to serve property abutting on State highways in cities or where urban type development is (d) When more than one driveway is to serve encountered. a given property, the total width of all driveways should not exceed 70 percent Details for driveway construction are shown on the of the frontage where such a frontage is Standard Plans. Corner sight distance requirements 100 feet or less. Where the frontage is more than 100 feet, the total driveway

HIGHWAY DESIGN MANUAL 200-27 July 24, 2009

width should not exceed 60 percent of the • In many cases providing the pathway along frontage. In either case, the width of the the back of the driveway will lower the individual driveway should not exceed elevation at the back of the sidewalk. those given in the preceding paragraphs. Depending on grades behind the sidewalk Where more than one driveway is the potential may exist for roadway necessary to serve any one property, not generated runoff to enter private property. less than 20 feet of full height curb should The need for features such as low berms be provided between driveways. This within the construction easement, or distance between driveways also applies installation of catch basins upstream of the to projects where curbs and gutters are not driveway should be determined. to be placed. When pedestrian activity is neither present, (e) Certain urban commercial driveways may nor expected to be present within the need to accommodate the maximum legal reasonable future, the designer may develop vehicle. The width will be determined by driveway details that eliminate the flatter the use of truck turn templates. portion along the back edge in lieu of using the Standard Plans for driveways. Refer to (5) Surfacing. Where curbs, gutters, and Topic 105 for additional information related to sidewalks are to be placed, driveways should pedestrian facilities. be constructed of portland cement concrete. Where only curbs and gutters are to be placed and pedestrian traffic or adjacent 205.4 Driveways on Frontage Roads and in improvements do not warrant concrete Rural Areas driveway construction, the driveway may be On frontage roads and in rural areas where the paved with the same materials used for maximum legal vehicle must be accommodated, existing surfacing on the property to be standard truck-turn templates should be used to served. determine driveway widths where the curb or edge (6) Pedestrian and Disabled Persons Access. of traveled way is so close to the right of way line Where sidewalks traverse driveways, that a usable connection cannot be provided within accessibility regulations require that a the standard limits. relatively level (2 percent max. cross fall) Where county or city regulations differ from the path, at least 4 feet wide, is provided. State's, it may be desirable to follow their Provision of this feature, as indicated in the regulations, particularly where jurisdiction of the Standard Plans, may require the acquisition of frontage road will ultimately be in their hands. a construction easement or additional right of way. Assessment of these needs must be Details for driveway construction are shown on the performed early enough in the design to allow Standard Plans. For corner sight distance, see time for acquiring any necessary permits or Index 405.1(2)(c). right of way. Additionally, designers should 205.5 Financial Responsibility consider the following: Reconstructing or relocating any access openings, • Where restricted parking zones have been private road connections, or driveways required by established (either blue or white painted revisions to the State highway facility should be zones) adjacent to driveways, but no done at State expense by the State or its agents. reasonably close ramp access to the Reconstruction or relocation requested by others sidewalk exists, consideration should be should be paid for by the requesting party. given to reducing the maximum slope of the driveway from 10 percent to 8.33 percent to provide sidewalk access to the disabled.

200-28 HIGHWAY DESIGN MANUAL October 4, 2010

Topic 206 - Pavement Transitions of situations should be at 10:1 (longitudinal to lateral). 206.1 General Transition Standards (4) Shoulder Widening. Shoulder widening Pavement transition and detour standards should be should normally be accomplished in a manner consistent with the section having the features built that provides a smooth transition, but can be to the highest design standards. The transition accomplished without a taper if necessary. should be made on a tangent section whenever possible and should avoid locations with horizontal 206.3 Pavement Reductions and vertical sight distance restrictions. Whenever (1) Through Lane Drops. When a lane is to be feasible, the entire transition should be visible to dropped, it should be done by tapering over a the driver of a vehicle approaching the narrower distance equal to WV, where W = Width of section. The design should be such that lane to be dropped and V = Design Speed. In intersections at grade within the transition area are general, the transition should be on the right avoided. For decision sight distance at lane drops, so that traffic merges to the left. Figure 206.2 see Index 201.7. provides several examples of acceptable lane drops at 4-lane to 2-lane transitions. The 206.2 Pavement Widenings exception to using the WV criteria is for the (1) Through Lane Additions. Where through lane drop/freeway merge movement on a lanes, climbing lanes, or passing lanes are branch connection which is accomplished added, the minimum recommended distance using a 50:1 taper. over which to transition traffic onto the (2) Ramp and Speed Change Lanes. As shown in additional width is 250 feet per lane. Figure Figures 504.2A and 504.3L, the standard taper 206.2 shows several examples of acceptable for a ramp merge into a through traffic lane is methods for adding a lane in each direction to 50:1 (longitudinal to lateral). Where ramp a two-lane highway. lanes are dropped prior to the merge with the (2) Turning, Ramp, and Speed Change Lanes. through facility, the recommended taper is Transitions for lane additions, either for left or 50:1 for design speeds over 45 miles per hour, right turns or to add a lane to a ramp, should and the taper distance should be equal to WV typically occur over a length of for speeds below 45 miles per hour. 120 feet. Lengths shorter than 120 feet are The "Ramp Meter Design Guidelines" also acceptable where design speeds are below provide information on recommended and 45 miles per hour or for conditions as stated in minimum tapers for ramp lane merges. These Index 405.2(2)(c). guideline values are typically used in retrofit Where insufficient median width is available or restricted right-of-way situations, and are to provide for left turn lanes, through traffic acceptable for the specific conditions stated in will have to be shifted to the outside. See the guidelines. Figures 405.2A, B and C for acceptable Figure 405.9 shows the standard taper to be methods of widening pavement to provide for used for dropping an acceleration lane at a median turn lanes. signalized intersection. This taper can also be (3) Lane Widening. An increase in lane width can used when transitioning median acceleration occur at short radius curves which are lanes. widened for truck off-tracking, at ramp Figures 405.2A, B and C show the terminals with large truck turning volumes, or recommended methods of transitioning when new construction matches existing pavement back into the median area on roadways with narrow lane widths. Extensive conventional highways after the elimination of transition lengths are not necessary as the left-turn lanes. widening does not restrict the drivers expectations. Transition tapers for these types

HIGHWAY DESIGN MANUAL 200-29 September 1, 2006

Figure 206.2

Typical Two-lane to Four-lane Transitions

200-30 HIGHWAY DESIGN MANUAL January 4, 2007

(3) Lane Reductions. At any location where lane widths are being reduced, the minimum 207.2 Clearances length over which to accomplish the transition (a) Civil Airports--See Figure 207.2A. should be equal to WV. See Index 504.6 for (b) Heliports--See Figure 207.2B. mainline lane reductions at interchanges. (c) Military Airports--See Figure 207.2C. (4) Shoulder Reduction Shoulder reductions . (d) Navy Carrier Landing Practice Fields--See should typically occur over a length equal to Figure 207.2D. ¾WV. However, when shoulder widths are being reduced in conjunction with a lane 207.3 Submittal of Airway-Highway addition or widening (as in Alt. A of Figure 504.3K), the shoulder reduction should be Clearance Data accomplished over the same distance as the The following procedure must be observed in addition or widening. connection with airway-highway clearances in the vicinity of airports and heliports. 206.4 Temporary Freeway Transitions Notice to the FAA is required when highway It is highly desirable that the design standards for a construction is planned near an airport (civil or temporary transition between the end of a freeway military) or a heliport. A "Notice of Proposed construction unit and an existing highway should Construction or Alteration" should be submitted to not change abruptly from the freeway standards. the FAA Administrator when required under Temporary freeway transitions must be reviewed criteria listed in Paragraph 77.13 of the latest by the Design Coordinator. Federal Aviation Regulations, Part 77. Such notice should be given as soon as highway alignment and Topic 207 - Airway-Highway grade are firmly established. It should be noted that these requirements apply to both permanent Clearances objects and construction equipment. When required, four copies of FAA Form 7460-1, “Notice 207.1 Introduction of Proposed Construction”, and accompanying scaled maps must be sent to the FAA, Western- (1) Objects Affecting Navigable Airspace. An Pacific Regional Office, Chief-Air Traffic object is considered an obstruction to air Division, AWP-520, 15000 Aviation Boulevard, navigation if any portion of that object is of a Hawthorne, CA 90260. Copies of FAA Form height greater than the approach and 7460-1 may be obtained from the FAA, Western- transverse surfaces extending outward and Pacific Regional Office or Caltrans, Division of upward from the airport runway. These Aeronautics. objects include overhead signs, light standards, moving vehicles on the highway The scaled maps accompanying FAA Form 7460-1 and overcrossing structures, equipment used should contain the following minimum during construction, and plants. information. (2) Reference. The Federal Aviation Administra- • Distance from project to nearest runway. tion (FAA) has published a Federal Aviation • Elevation of runway thresholds. Regulation (FAR) relative to airspace clearance entitled, “FAR Part 77, Obstructions • Relationship between the proposed Affecting Navigable Airspace”, dated March highway horizontal alignment and vertical 1993. This is an approved reference to be profile to the nearest runway or heliport used in conjunction with this manual. primary surface. Include elevations of objects referenced to the elevation of the end of the runway, such as overhead lights, signs, structures, landscaping, and vehicles.

HIGHWAY DESIGN MANUAL 200-31 September 1, 2006

Figure 207.2A

Airway-Highway Clearance Requirements (Civil Airports)

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Figure 207.2B

Airway-Highway Clearance Requirements (Heliport)

HIGHWAY DESIGN MANUAL 200-33 September 1, 2006

Figure 207.2C

Airway-Highway Clearance Requirements (Military Airports)

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Figure 207.2D

Airway-Highway Clearance Requirements (Navy Carrier Landing Practice Field)

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One copy of FAA form 7460-1 should be If the undercrossing street or road has no forwarded to the Division of Design for median, one should be provided where information and one copy to the Division of necessary to accommodate left-turn lanes Aeronautics for information and land use or the center piers of the undercrossing compatibility review. structure. Where it appears that a 2-lane road will be Topic 208 – Bridges, Grade adequate for the foreseeable future, but no Separation Structures, and right of way width has been established, a minimum span length sufficient for a 40- Structure Approach Embankment foot roadbed should be provided. Additional span length should be provided 208.1 Bridge Width to permit future sidewalks where there is a (1) State Highways. The clear width of all foreseeable need. If it is reasonably bridges, including grade separation foreseeable that more than two lanes will structures, shall equal the full width of the be required ultimately, a greater width traveled way and paved shoulders on the should be spanned. approaches with the following exceptions: (c) For horizontal and vertical clearances, see (a) Bridges to be constructed as Topic 309. replacements on existing 2-lane, 2-way roads shall not have less than a 32-foot 208.2 Cross Slope wide roadbed for ADT less than 400, The crown is normally centered on the bridge and not less than 40-foot wide roadbed except for one-way bridges where a straight cross for ADT greater than 400. (see Index slope in one direction should be used. The cross 307.2). slope should be the same as for the approach pavement (see Index 301.2). (b) When the approach shoulder width is less than 4 feet, the minimum offset on 208.3 Median each side shall be 4 feet, and shall be On multilane divided highways a bridge median documented in accordance with Index that is 36 feet wide or less should be decked. 82.2. Exceptions require individual analysis. See The width should be measured normal to the Chapter 7 of the Traffic Manual for median barrier center line between faces of curb or railing warrants. measured at the gutter line. For offsets to safety shape barriers see Figure 208.1. 208.4 Bridge Sidewalks For horizontal and vertical clearances, see Bridge sidewalks should be provided where Topic 309. justified by pedestrian traffic (see Figure 208.10B). (2) Roads Under Other Jurisdictions. 208.5 Open End Structures (a) Overcrossing Widths--(See Index 308.1.) Embankment end slopes at open end structures (b) Undercrossing Span Lengths--Initial should be no steeper than 1½:1 for all highways. construction should provide for the 208.6 Pedestrian Overcrossings and ultimate requirements. In areas where the local jurisdiction has a definite plan of Undercrossings development, the ultimate right of way The minimum width of walkway for pedestrian width or at least that portion needed for overcrossings should be 8 feet. the roadbed and sidewalks should be spanned.

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Figure 208.1 Offsets to Safety-Shape Barriers

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Determination of the width and height of pedestrian (a) A deer crossing or other structure for undercrossings requires individual analysis to environmental protection purposes. insure adequate visibility through the structure and (b) Equipment crossings for the Forest approaches (see Index 105.2). Service or other governmental agencies or Pedestrian ramps should be provided on all as a right of way obligation. pedestrian separation structures. The ramp should These facilities should be installed where necessary have a maximum longitudinal slope of 8.33 percent as determined by consultation with the appropriate with a maximum rise of 30 inches between affected entities. landings. The landing should be a minimum of 5 feet in length. A clear line of sight should be provided through the structure. See Topic 309 for vertical clearances. 208.9 Railroad Underpasses and Overheads 208.7 Equestrian Undercrossings Generally, it is desirable to construct overheads Such structures should normally provide a clear rather than underpasses whenever it is necessary opening 10 feet high and 10 feet wide. Skewed for a highway and railroad to cross. Railroads crossings should be avoided. The structure should should be carried over highways only when there is be straight so the entire length can be seen from no other reasonable alternative. each end. Sustained grades should be a maximum of 10 percent. Decomposed granite or similar Some undesirable features of underpasses are: material should be used for the trail surface. While (a) They create bottlenecks for railroad flexible pavement is permissible, a rigid pavement operations. should be avoided. (b) It is difficult to widen the highway. 208.8 Cattle Passes, Equipment, and Deer (c) Pumping plants are often required to drain Crossings the highway. Private cattle passes and equipment crossings may (d) They are likely to lead to cost be constructed when economically justified by a participation controversies for initial and right of way appraisal, as outlined in Section future construction. 7.09.09.00 of the Right of Way Manual. (e) Shooflies (temporary tracks) are generally The standard cattle pass should consist of either a required during construction. standard box culvert with an opening 8 feet wide and 8 feet high or a metal pipe 120 inches in (f) Railroads are concerned about the diameter. The invert of metal pipe should be paved structure maintenance and liability costs with concrete or bituminous paving material. they incur. If equestrian traffic is expected to use the culvert a Advantages of overheads are: minimum 10 feet wide by 10 feet high structure (a) Railroads can use most of their right of may be provided. However, the user of the facility way for maintenance. should be contacted to determine the specific requirements. (b) Overheads can be widened at a relatively low cost and with little difficulty. If conditions indicate a reasonable need for a larger than standard cattle pass, it may be provided if (c) Less damage may be incurred in the event economically justified by the right of way of a derailment. appraisal. (d) Agreements for design and maintenance In some cases the installation of equipment or deer can be reached more easily with railroads. crossings is justified on the basis of public interest (e) Initial costs are generally lower. or need rather than economics. Examples are:

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The State, the railroads, and the public in general Railings and barriers with sidewalks should can usually benefit from the construction of an not be used on structures with posted speeds overhead structure rather than an underpass. greater than 45 miles per hour without barrier separation. All structure railings with a See Topic 309 for vertical clearances. sidewalk in the Standard Plans are approved for posted speeds up to 45 miles per hour. 208.10 Bridge Barriers and Railings Any use of railings and barriers with (1) General. There are four classes of railings, sidewalks on structures with posted speeds each intended to perform a different function. greater than 45 miles per hour shall have a (a) Vehicular Barrier Railings--The primary barrier separation between the roadway function of these railings is to retain and and the sidewalk. The barrier separation type redirect errant vehicles. and the bridge rail selection requires approval by the HQ Traffic Liaison. (b) Combination Vehicular Barrier and Pedes- trian Railings--These railings perform the The approved types of railings for use on dual function of retaining both vehicles bridge structures are listed below and and pedestrians on the bridge. They illustrated in Figures 208.10A, B, and C. consist of two parts--A concrete parapet Railing types not listed are no longer in barrier, generally with a sidewalk, and general use; however, they may be specified metal handrailing or fence-type railing. in those cases where it is desirable to match an existing condition. (c) Pedestrian Railings--These railings pre- vent pedestrians from accidentally falling The District should specify in the bridge site from the structure and, in the case of data submittal the rail type to be used after fence-type railing, reduce the risk of consideration has been given to the objects being dropped on the roadway recommendations of the local agency (where below. Where the facility is accessible to applicable) and the DES-SD. disabled persons and the profile grade (3) Vehicular Barriers. See Figure 208.10A. exceeds 5 percent, a handrail for use by (a) Concrete Barrier Type 732 and 736-- the disabled meeting both the State and These vehicular barriers are for general Federal regulations must be provided. use adjacent to traffic. Figure 208.1 (d) Bicycle Railings--These railings retain illustrates the position of the barrier bicycles and riders on the structure. They relative to the edge of traveled way. may be specifically designed for bicycles, (b) Concrete Barrier Type 80--Use of this or may be a combination type consisting barrier requires approval by the HQ of a vehicular barrier surmounted by a Traffic Liaison. It is intended for use in fence or metal handrail. lower speed scenic areas where more see- (2) Policies. To reduce the risk of objects being through area is desired than is provided by dropped or thrown upon vehicles, protective a solid concrete parapet. screening in the form of fence-type railings should be installed along new overcrossing (4) Combination Railings. See Figure 208.10B. structure sidewalks in urban areas (Sec.92.6 (a) Barrier Railing Type 26--This is the California Streets and Highways Code). barrier railing for general use when Screening should be considered for the sidewalks are provided on a bridge. It opposite side of structures having one must be accompanied with a tubular sidewalk. Screening should be installed at handrailing or a fence-type railing. The such other locations determined to be minimum sidewalk width is 5 feet, appropriate. however, this width may be varied as circumstances require.

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(b) Barrier Railing Type 80SW--Similar to is restricted to those locations where the Type 80, modified with a raised object dropping or throwing will not be a sidewalk and tubular handrailing. Use of problem. this barrier requires approval by the HQ (d) Chain Link Railing (Modification)-- Traffic Liaison. It is intended for use in Existing railing may be modified for lower speed scenic areas where more see- screening under the protective screening through area is desired than is provided by policy. The DES-SD should be contacted a solid concrete parapet. for details. (c) Chain Link Railing Type 7--This is the (6) Bicycle Railing. The minimum height of fence-type railing for general use with bicycle rail is 54 inches above the deck Type 26 barrier railing with sidewalk to surface. Pedestrian railings and combination reduce the risk of objects being dropped railings consisting of a concrete barrier on the roadway below. When a sidewalk surmounted by a fence or tubular railing are (Type 26 railing) is provided on one side satisfactory for bicycles, if at least 54 inches of a bridge and Type 732 barrier railing high. Bicycles are not considered to operate on the other side, Type 7 railing may be on a sidewalk, except in special cases where placed on top of the Type 732 as signs specifically direct cyclists to use the additional protection from dropped sidewalk. objects. Consideration should be given to the effect of the Type 7 railing on sight As a general policy, bicycle railings should be distance at the bridge ends and view over installed at the following locations: the side of the bridge. Lighting fixtures (a) On a Class I bikeway, except that a lower may be provided with Type 7 railings. rail may be used if a curbed sidewalk, not (d) Chain Link Railing Type 6--This railing signed for bicycle use, separates the may be used in lieu of Type 7 when bikeway from the rail or a shoulder at special architectural treatment is required. least 8 feet wide exists on the other side of It should not be used on curved alignment the rail. because of fabrication difficulties. (b) On the outside of a Class II or III (e) Tubular Handrailing--This railing is used bikeway, unless a curbed sidewalk, not with Type 26 and Type 80SW to increase signed for bicycle use, separates the the combined rail height for the safety of bikeway from the rail. pedestrians. It should be used in lieu of (c) In other locations where the designer Type 7 where object dropping will not be deems it reasonable and appropriate. a problem or at the ends of bridges to increase sight distance if fence-type (7) Bridge Approach Railings. Approach railing would restrict sight distance. railings shall be installed at the ends of bridge railings exposed to approach traffic. (5) Pedestrian Railings. See Figure 208.10C Refer to Chapter 7 of the Traffic Manual for (a) Chain Link Railing Type 3--This railing is placement and design criteria of guardrail. used on pedestrian structures to reduce the risk of objects being dropped on the 208.11 Structure Approach Embankment roadway below. (1) General. Structure approach embankment is (b) Chain Link Railing Type 7 (Modified)-- that portion of the fill material within This railing is similar to Type 7 except approximately 150 feet longitudinally of the that it is mounted on the structure at the structure. Refer to Figure 208.11A for limits, sidewalk level. the Standard Specifications, and Standard (c) Chain Link Railing --This railing is not as Special Provisions for more information. high as Types 3 or 7 and therefore, its use

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Quality requirements for embankment abutment embankments, the designer may material are normally specified only in the specify select material, local borrow, or case of imported borrow. When select imported borrow to satisfy the design material or local borrow for use in structure requirements. abutment embankments is shown on the (3) Abutment Drainage. Special attention must plans, the Resident Engineer (RE) is be given to providing a positive drainage responsible for assuring the adequacy of the system that minimizes the potential for water quantity and quality of the specified material. damage to the structure approach The Project Engineer should include adequate embankment, see Chapter 870 for further information and guidance in the RE File to details. The Division of Engineering Services assist the RE in fulfilling this responsibility. (DES), Structures Design (DES-SD) is (2) Foundations and Embankment Design. responsible for the design of the structure Overall performance of the highway approach approach drainage system, which includes: to the bridge depends, to a significant degree, • A geocomposite drain covered with filter upon the long-term settlement/consolidation fabric placed behind both the abutment of the approach foundation and structure wall and wingwalls, as indicated in Figure abutment embankment. A design that 208.11B. minimizes this post construction settlement/consolidation is essential. Factors • A slotted plastic pipe drain, encapsulated that influence settlement/consolidation with treated permeable material, placed include soil types and depths, static and along the base of the inside face of the dynamic loads, ground water level, adjacent abutment wall as illustrated in Figure operations, and changes in any of the above. 208.11B. The PE must follow the foundation and (4) Slope Treatment. See Topic 707, Slope embankment recommendations by the Treatment Under Structures, for guidance Division of Engineering Services, regarding the treatment of bridge approach Geotechnical Services (DES-GS) and District end slopes. Materials Engineer (DME). The DME and/or DES-GS must approve any deviations from The District Hydraulic Engineer or Project their recommendations including Engineer must design a pipe outlet that ties Construction Change Orders (CCO’s). into the structure approach drainage system as it exits the structure. A pipe outlet system The relative compaction of material within the should carry the collected water to a location embankment limits must be at least 95 where it will not cause erosion. Storm Water percent, except for the outer 5 feet of Best Management Practices should be embankment measured horizontally from the incorporated. For further information on side slope (see Figure 208.11A). The DME Storm Water Management, visit the Division and/or OSF may recommend using select of Design Storm Water website. material, local and/or imported borrow to assure that the compaction requirements are Coordination with DES is necessary for the met and that shrink/swell problems are exit location of the pipe system. The outlet avoided. They may also recommend a height type should be chosen from the standard edge and duration of embankment surcharge to drain outlet types shown in the Standard Plans accelerate foundation consolidation. or tied into an underground drainage system. The PE must review the drainage design to Poor quality material, such as expansive soils, ensure the adequacy of the drainage ties must be precluded from structure abutment between the structure approach drainage embankments unless treated. If sufficient system and either new or existing drainage quality roadway excavation material is facilities. For alternative details, see Bridge unavailable for constructing of structure Design Aids.

HIGHWAY DESIGN MANUAL 200-41 September 1, 2006

Figure 208.10A

Vehicular Railings for Bridge Structures

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Figure 208.10B

Combination Railings for Bridge Structures

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Figure 208.10C

Pedestrian Railings for Bridge Structures

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Figure 208.11A

Limits of Structure Approach Embankment Material

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Figure 208.11B

Abutment Drainage Details

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reinforcement is placed behind the face of Topic 209 – (currently not in use) the reinforced slope or earth retaining system. It should be noted that if a “Retaining Wall” earth retaining system is Topic 210 - Reinforced Earth to be used in a cut situation, a temporary Slopes and Earth Retaining back cut or shoring system is required Systems behind the wall. The District Project Engineer (PE) should 210.1 Introduction conduct an initial site visit and assessment to Constructing roadways on new alignments, determine all potential construction widening roadways on an existing alignment, or limitations. The preferred construction repairing earth slopes damaged by landslides are method is top-down due to the reduced situations that may require the use of reinforced shoring, excavation and backfilling. However, earth slopes or earth retaining systems. Using cut this method is not always available or and embankment slopes that are configured at slope appropriate based on the physical and ratios that are stable without using reinforcement is geotechnical site conditions. The site should usually preferred; however, topography, also be examined for R/W or utility environmental concerns, and right of way (R/W) constraints that would restrict the type of limitations may require the need for reinforced excavation or limit the use of some earth slopes or an earth retaining system. equipment. In addition, the accessibility to the site for construction and contractor staging The need for reinforced earth slopes or an earth areas should be considered. retaining system should be identified as early in the project development process as possible, preferably Table 210.2 summarizes the various during the Project Initiation Document (PID) reinforced earth slopes and earth retaining phase. systems that are currently available for use, along with the method in which they are 210.2 Construction Methods and Types constructed. (1) Construction Methods. (2) Reinforced Earth Slopes (PS&E by District PE) Both reinforced earth slopes and earth retaining systems can be classified by the Reinforced earth slopes incorporate metallic method in which they are constructed, either or non-metallic reinforcement in construction top-down or bottom-up. of embankments and cut slopes with a slope angle flatter than 70 degrees from the • “Top-down” construction –This method horizontal plane. Reinforced earth slopes of construction begins at the top of the should be used in conjunction with erosion reinforced slope or earth retaining system mitigation measures to minimize future and proceeds in lifts to the bottom of the maintenance costs. The slope face is typically reinforced slope or earth retaining system. erosion protected with the use of systems such If required, reinforcement is inserted into as geo-synthetics, bio-stabilization, rock slope the in situ material during excavation. protection, or reinforced concrete facing. • “Bottom-up” construction – This method (3) Earth Retaining Systems of construction begins at the bottom of the Earth retaining systems can be divided into reinforced slope or earth retaining system, five major categories depending upon the where a footing/leveling pad is nature of the design and whether they are constructed, construction then proceeds designed by the owner (State designed), a towards the top of the reinforced slope or Proprietary vendor or a combination thereof. earth retaining system. If required, The term “State designed” as referenced

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herein is utilized to encompass earth retaining height. See Standard Plans B3-5 and systems that are designed by the State or by B3-6 for further details. Local or Private entities on behalf of the • Retaining Wall Type 5 (Concrete L- State. No assignment of roles and Type Cantilever). This wall has a responsibilities is intended. The five design height up to 12 feet. Although categories are as follows: more costly than cantilever walls, (a) State Designed Earth Retaining Systems these walls may be required where which utilize Standard Plans (PS&E by site restrictions do not allow for a District PE). footing projection beyond the face of the wall stem. See Standard Plan B3-7 Standard Plans are available for a variety for further details. of earth retaining systems (retaining walls). Loading conditions and foundation • Retaining Wall Type 6 (Concrete requirements are as shown on the Masonry Walls). These walls may be Standard Plans. For sites with used where the design height of the requirements that are not covered by the wall does not exceed 6 feet. These Standard Plans, a special design is walls are generally less costly than all required. To assure conformance with the other standard design walls or gravity specific Standard Plan conditions and walls. Where traffic is adjacent to the requirements, and subsequent completion top of the wall, guardrail should be set of the PS&E in a timely fashion, the back as noted in the Standard Plans. District PE should request a foundation See Standard Plan B3-11 for further investigation for each location where a details. retaining wall is being considered. • Crib Walls. The following types are Retaining walls that utilize Standard Plans available: are as follows: Concrete Crib Wall - This type of • Retaining Wall Types 1, 1A and 2 crib wall may be used for design (Concrete Cantilever). These walls heights up to 50 feet. Concrete have design heights up to 36 feet, 12 crib walls are suited to coastal feet and 122 feet, respectively, but are areas and higher elevations where most economical below 20 feet. salt air and deicing salts may limit Concrete cantilever walls can the service life of other types of accommodate traffic barriers, and crib walls. See Standard Plans drainage facilities efficiently. See C7A to C7G for further details. Standard Plans B3-1, B3-2, B3-3, B3- 4, B3-8 and B3-9 for further details. Steel Crib Wall - This type of crib wall may be used for design • Retaining Wall Types 3 and 4 heights up to 36 feet. Steel crib (Concrete Counterfort). These walls walls are light in weight; easily have design heights up to 36 feet and transported and installed; and, 30 feet respectively. These walls may therefore, suited for relatively be used where minimum horizontal inaccessible installations and for wall deflection is desired. When used emergency repairs. See Standard in conjunction with concrete Plans C8A to C8C for further cantilever walls, there should be an details. offset in the plane of the wall faces to mask the difference in deflection Timber Crib Wall - This type of between the two wall types. The cost crib wall may be used for design of these walls is generally more than heights up to 22 feet. Timber crib for concrete cantilever walls of similar walls have a rustic appearance

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which makes them suitable for walls, secant soldier pile walls, slurry use in rural environments. When diaphragm walls, and deep soil mixing all of the wood members are walls. These walls are most practical in pressure preservative treated, the cut sections and are best suited for service life of timber crib walls is situations where excavation for a comparable to that of concrete or retaining wall with a footing is steel crib walls. See Standard impractical because of traffic, utilities, Plans C9A and C9B for further existing buildings, or R/W restrictions. details. In embankment sections, a non-gravity cantilevered wall is a practical solution Timber and concrete crib walls for a roadway widening where design constructed on horizontal alignments heights are less that 15 feet. They are with curves or angle points require also practical for slip-out corrections. special details, particularly when the Non-gravity cantilevered walls can wall face is battered. Because crib wall consist of concrete, steel, timber, or faces can be climbed, they are not cemented soil piles that may be either recommended for use in urban driven into place or placed in drilled locations where they may be accessible holes and trenches. to the public. • Anchored Walls (PS&E by Structure (b) State Designed Earth Retaining Systems PE). These walls are typically which requires Special Designs. composed of the same elements as non- Some locations will require a special gravity cantilevered walls, but derive design to accommodate ground contours, additional lateral resistance from traffic, utilities, man-made features, site ground anchors (tiebacks), concrete geology, economics, or aesthetics. anchors, or pile anchors. These Some special design earth retaining anchors are located behind the systems are as follows: potential failure surfaces in the retained soil and are connected to the wall • Standard Plan Walls (PS&E by structurally. The method of support Structure PE). The design loadings, and anchorage depends on site heights, and types of walls in the conditions, design height, and loading Standard Plans cover frequent imposed. The cost of these walls is applications for earth retaining variable depending on earth retaining systems. However, special designs are requirements, site geology, aesthetic necessary if the imposed loading consideration, and site restraints, but is exceeds that shown on the Standard generally higher than “Standard Design Plan. Railroad live loads; building Walls” for the same wall geometry and surcharge; loads imposed by sign loading conditions. Anchored walls structures, electroliers, or noise barriers may be used to stabilize an unstable are examples of loading conditions that site provided that adequate material will require special designs. exists at the site for the anchors. Foundation conditions that require pile Economical wall heights up to 80 feet support for the wall and angle points in are feasible. the wall geometry necessitate a special design. • Gravity Wall Systems that require special designs are Concrete Gravity, • Non-Gravity Cantilevered Walls Rock Gravity, and Gabion Basket (PS&E by Structure PE). These walls Walls. include sheet pile walls, soldier pile walls with lagging, tangent soldier pile

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Table 210.2 (1) Types of Reinforced Earth Slopes and Earth Retaining Systems EARTH RETAINING SYSTEM Construction PS&E Typical Facing Recommended Ability to Method(2) By Material Maximum Tolerate Vertical Differential Height, ft Settlement(3) Reinforced Earth Slopes Reinforced Embankments BU District PE Vegetation/Soil 160 E Rock/Soil Anchors TD District PE Soil/Rock 130 E State Designed Earth Retaining Systems with Standard Plans Concrete Cantilever Wall, Type 1, 1A & 2 BU District PE Concrete 36, 12, 22(4) P Concrete Counterfort Wall, Type 3 & 4 BU District PE Concrete 36, 30(4) P Concrete L-Type Cantilever Wall, Type 5 BU District PE Concrete 12(4) P Concrete Masonry Wall, Type 6 BU District PE Masonry 6(4) P Crib Wall: Concrete, Steel or Timber BU District PE Concrete, Steel, 50, 36, 22(4) P Timber State Designed Earth Retaining Systems Which Require Special Designs Standard Plan Walls with modified wall BU Structure PE Concrete, Steel, 50 P-F geometry, foundations or loading Timber conditions Non-Gravity Cantilevered Walls Sheet Pile Wall TD Structure PE Steel 20 F Soldier Pile Wall with Lagging TD/BU Structure PE Concrete, Steel, 20 F-G Timber Tangent Soldier Pile Wall TD/BU Structure PE Concrete 30 F Secant Soldier Pile Wall TD Structure PE Concrete 30 F Slurry Diaphragm Wall TD Structure PE Concrete,Shotcrete 80(5) F Deep Soil Mixing Wall TD Structure PE Shotcrete 80(5) F-G Anchored Wall (Structural or Ground TD Structure PE Concrete, Steel, 80(6) F-G Anchors) Timber Gravity Walls Concrete Gravity Wall BU Structure PE Concrete 6 P Rock Gravity Wall BU District PE Rock 13 E Gabion Basket Wall BU District PE Wire & Rock 26 E Soil Reinforcement Systems Mechanically Stabilized Embankment BU Structure PE Concrete 50 G Salvaged Material Retaining Wall BU District PE Steel, Timber 16 G Soil Nail Wall TD Structure PE Concrete,Shotcrete 80 F Tire Anchored Timber Wall BU District PE Timber 32 G Proprietary Earth Retaining Systems (Pre-approved) The list of Pre-approved systems is available at the website shown in Index 210.2(3)(c). Proprietary Earth Retaining Systems (Pending) These systems are under review by DES-SD. For more information, see Index 210.2(3)(d). Experimental State Designed Earth Retaining Systems Geosynthetic Reinforced Walls BU Structure PE/ Concrete Blocks, 65 E District PE Steel, Vegetation, Fabric Mortarless Concrete Blocks Gravity Walls BU District PE Concrete Blocks 8 P Notes: 1. Comparative cost data is available from DES-SD. 4. Maximum Design Height 2. BU = Bottom Up; TD = Top Down 5. Anchors may be required 3. E = Excellent; G = Good; F = Fair; P = Poor 6. With lagging

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Concrete Gravity Walls (PS&E by situ soil mass. The reinforced soil Structure PE). Concrete gravity walls mass functions similar to a gravity are most economical at design heights wall. below 4 feet. However, they may be Soil reinforcing elements can be any constructed at heights up to 6 feet. material that provides tensile strength These walls can be used in connection and pullout resistance, and possesses with a cantilever wall if long lengths of satisfactory creep characteristics and wall with design heights of less than service life. Generally, reinforcing 4 feet are required. A Type 50C elements are steel, but polymeric and concrete barrier, see Standard Plans, fiberglass systems may be used. can serve as a gravity retaining wall at locations where the differential height Facing elements for most systems are between the adjoining roadway grades either reinforced concrete, light guage is equal to or less than 3 feet. steel, or treated wood. Polymeric reinforced walls may be faced with Rock Gravity Walls (PS&E by District masonry-like elements or even planted PE). Rock gravity walls consist of with local vegetation. Selection of rocks that are 100 pounds to 200 facing type is governed by aesthetics pounds, stacked on top of each other at and service life. slight batter. These walls are typically used in areas where a rock appearance Wall heights of soil reinforcement is desirable for aesthetic reasons. Wall systems are controlled mainly by heights range from 1 foot 6 inches to bearing capacity of the foundation 15 feet, but are most economical for material and site stability. Wall heights less than 10 feet. heights in excess of 60 feet are feasible where conditions permit. Foundation Gabion Basket Walls (PS&E by investigations for soil reinforcement District PE). Gabion basket walls use systems are similar to investigations compartmented units filled with stones for conventional retaining walls. and can be constructed up to 26 feet in height. Each unit is a rectangular Special details are required when basket made of galvanized steel wire. drainage structures, overhead sign The stone fill is 4 inches to 16 inches supports or noise barriers on piles are in size. Gabion basket walls are within the reinforced soil mass. typically used for soil and stream bank Concrete traffic barriers require a stabilization. Service life of the gabion special design support slab when used basket wall is highly dependent on the at the top of the facing of these environment in which they are placed. systems. These systems cannot be Corrosion, abrasion, rock impact, fire used where site restrictions do not and vandalism are examples of site- allow necessary excavation or specific factors that would influence placement of the soil reinforcing the service life of the wall and should elements. be taken into consideration by the Soil reinforcement systems that require District PE during the design of the special design are as follows: project. See Standard Plans D100A and D100B for further details. • Mechanically Stabilized Embankment (MSE) (PS&E by Structure PE). This • Soil Reinforcement Systems. Soil system uses welded steel wire mats, reinforcement systems consist of facing steel strips or polymeric materials as elements and soil reinforcing elements soil reinforcing elements. The facing incorporated into a compacted or in elements are precast concrete. In many

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cases, this system can be constructed height of wall has been excavated and using on-site backfill materials. reinforced, a finish layer of concrete facing is placed either by the When the bottom-up construction shotcreting method or by casting method is possible and other conditions within a face form. permit their use, these systems are generally the most economical choice When top-down construction is for wall heights greater than 20 feet. possible and conditions permit its use, They may also be the most economical soil nail wall systems are generally the system for wall heights in the 10-foot most economical choice for wall to 20-foot range, depending on the heights greater than 10 feet. Wall specific project requirements. heights in excess of 80 feet are feasible in specific locations. Because of the articulated nature of the facing elements these systems use, they Because soil nailing is accomplished can tolerate greater differential concurrent with excavation, and thus settlement than can monolithic results in an unloading of the conventional rigid retaining walls, such foundation, there is typically no as concrete cantilever retaining walls. significant differential settlement. Steel elements used in this method are Steel "soil nails" used in this method sized to provide sacrificial steel to are protected against corrosion either compensate for anticipated corrosion; by being epoxy coated or encapsulated and may be galvanized to provide within a grout filled corrugated plastic additional protection. sheath, and surrounded by portland cement grout placed during • Salvaged Material Retaining Wall construction. Soil nail lengths (PS&E by District PE). This system typically range from 80 to 100 percent utilizes C-channel sections as soil of the wall height, the actual length reinforcement. Galvanized metal beam depends on the nail spacing used and guardrail, timber posts or concrete the competency of the in situ soil. panels are used as facing elements. Often these materials can be salvaged • Recycled Tire Anchor Timber (TAT) from projects. The District Recycle Walls (PS&E by District PE). This Coordinator should be consulted as to system utilizes steel bars with recycled the availability of salvaged materials. tire sidewalls attached by cross bars as soil reinforcing elements. The facing • Soil Nail Wall (PS&E by Structure elements are treated timber. TAT PE). This system reinforces either the walls have a rustic appearance, which original ground or an existing makes them suitable in rural embankment during the excavation environments. The length of process. Soil nailing is always commercially available timber post accomplished from the top-down in generally controls the height of wall stages that are typically 4 feet to 6 feet but heights up to in height. After each stage of 32 feet are feasible. excavation, corrosion protected soil reinforcing elements, "soil nails", are (c) Proprietary Earth Retaining Systems (Pre- placed and grouted into holes which approved). have been drilled at angles into the in These conventional retaining walls, situ material. The face of each stage of cribwalls, and soil reinforcement systems excavation is protected by a layer of are designed, manufactured, and marketed reinforced shotcrete. After the full by vendors. These systems are termed

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“proprietary” because they are patented. Every earth retaining system is evaluated “Pre-approval” status means that these before being approved for routine use by systems may be listed in the Special the Department. Newly introduced Provisions of the project as an Alternative designs, unproven combinations of Earth Retaining System (AERS), see proprietary and non-proprietary designs or Index 210.3, when considered appropriate products, are considered experimental. for a particular location. For a proprietary Once an experimental system has been system to be given “pre-approval” status, evaluated and approved, it will be made the vendor must submit standard plans available for routine use. The use of these and design calculations to the Division systems is only permitted upon of Engineering Services – Structure consultation with the Division of Design (DES-SD) for their review and Engineering Services – Geotechnical approval. The Proprietary earth retaining Services (DES-GS). systems that have been pre-approved are Some earth retaining systems which are included in the Department’s Pre- currently considered experimental follow: Qualified Products List, located on the following website: www.dot.ca.gov/hq/ • Geo-synthetic Reinforced Walls esc/approved_products_list/ . (PS&E by District PE). These systems utilize geo-synthetic material as the Design details and specifications of “pre- soil reinforcing elements. The face of approved” proprietary earth retaining these walls can be left exposed if the systems may be found on the vendor geo-synthetic material has been treated websites listed in the Pre-Qualified to prevent decay from ultra-violet rays. Products List. New systems are added to Concrete panels, mortarless masonry, the website list once they are pre- tar emulsion, or air blown mortar may approved for use. be used as facing materials or the face (d) Proprietary Earth Retaining Systems may be seeded if a more aesthetic (Pending). treatment is preferred. Design is by DES-GS. The systems in this category have been submitted by vendors to DES-SD for • Mortarless Concrete Block Gravity evaluation. Upon approval of DES-SD, Walls (PS&E by District PE). These pending systems are added to the website wall types consist of vertically stacked, list of “pre-approved” proprietary earth dry cast, concrete blocks. This system retaining systems and included in the utilizes the friction and shear project specific Special Provisions. developed between the blocks and the combined weight of the blocks to If a proprietary system is the only retain the backfill. Some of these walls retaining system deemed appropriate for have been used as erosion protection at use at a specific location, the construction abutments and on embankments. They of that system must be justified or can be used as an aesthetic treatment designated an experimental construction for geo-synthetic material reinforced feature in accordance with existing walls. All of these walls require a Departmental Policy concerning sole batter. Design is by the DES-GS. source purchases. See Index 110.10 for additional guidance on the use of 210.3 Alternative Earth Retaining Systems proprietary items. (AERS) (e) Experimental State Designed Earth Retaining Systems. Using the Alternative Earth Retaining Systems (AERS) procedure encourages competitive bidding and potentially results in project cost savings.

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Therefore, AERS must be considered in all projects The earth retaining systems utilizing this procedure where earth retaining systems are required. are to be measured and paid for by the square yard area of the face of the earth retaining system. The AERS procedure may result in one or more Should an AERS be constructed, payment will be earth retaining systems being included in the made based on the measurements of the State contract bid package. Under this procedure, a fully designed system which was designated as the basis detailed State designed earth retaining system will of payment. The contract price paid per square be provided for each location, and will be used as yard is for all items of work involved and includes the basis for payment. Additional systems may be excavation, backfill, drainage system, reinforcing presented in the contract documents as alternatives steel, concrete, soil reinforcement, and facing. Any to the fully detailed State design and can be barrier, fence, or railing involved is measured and considered for use at specified locations. The fully paid for as separate contract cost items. detailed State designed earth retaining system may be either a Standard Plan system or a special design system. Alternative systems may also be State 210.4 Cost Reduction Incentive Proposals designed systems, “pre-approved” proprietary (CRIP) systems or experimental systems, as appropriate. Sometimes Contractors submit proposals for an The State designed alternative systems, both earth retaining system under Section 5-1.14 of the Standard Plan walls and special design systems, are Standard Specifications, “Cost Reduction to be completely designed and specified in the Incentive.” The Contractor proposed system may PS&E. Alternative systems are to be listed in the modify or replace the earth retaining system Special Provisions as AERS. permitted by the contract. The CRIP process The AERS procedure requires the involvement of allows vendors of proprietary earth retaining the District PE, DES-SD, and the DES-GS. The systems an alternative method for having their District PE should submit pertinent site information systems used prior to obtaining “pre-approval” (see (site plans, typical sections, etc.) to DES-GS for a Index 210.2(c)). CRIP submittals are administered feasibility study as early as possible in the project by the Resident Engineer. However, Contract development process. Change Orders are not to be processed until the CRIP is approved by Headquarters Construction Under the AERS procedure, parts of the PS&E with review assistance provided by the District or package which pertain to the earth retaining Structure PE as appropriate. systems will be prepared as follows: • Contract plans for State designed systems 210.5 Aesthetic Consideration can be prepared by the District PE The profile of the top of wall should be designed to (Standard Plan systems), the DES-GS be as pleasing as the site conditions permit. All (special design soil reinforcement systems changes in the slope at the top of cast-in-place and experimental systems), or the Structure concrete walls should be rounded with vertical PE (Standard Plan systems and special curves at least 20 feet in length. Abrupt changes in design systems). the top of the wall profile should be avoided by • “Pre-approved” proprietary systems that using vertical curves, slopes, steps, or combinations are determined, based on consultation with thereof. Side slopes may be flattened or other DES-SD, to be appropriate alternatives to adjustments made to provide a pleasing profile. the State designed earth retaining system, Where walls are highly visible, special surface are to be listed in the Special Provisions. treatments or provisions for landscaping should be • Specifications and Estimates shall be considered. The aesthetic treatment of walls should developed for the fully detailed State be discussed with the District Landscape Architect designed system, which will be used as the and when necessary referred to DES Structure basis for payment. Design Services & Earthquake Engineering for

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additional study by the Office of Transportation 210.7 Design Responsibility Architecture. The Structure PE has primary responsibility for the The wall area between the grade line and 6 feet structural design and preparation of the contract above it shall be free of any designed indentations documents (PS&E) for special design earth or protrusions that may snag errant vehicles retaining systems involving Standard Plans non- When alternative wall types are provided on gravity cantilevered walls, anchored walls, concrete projects with more than one wall site, any and rock gravity walls, mechanically stabilized restrictions as to the combination of wall types embankment, and soil nail walls. The DES-GS has should be specified in the Special Provisions. primary responsibility for the geotechnical design of all reinforced earth slopes and earth retaining 210.6 Safety Railing, Fences, and Concrete systems. DES-SD will prepare the Specifications and Engineer's Estimate for contracts when the Barriers AERS procedure is used. DES-SD reviews and Cable railing shall be installed for employee approves standard plan submittals for proprietary protection in areas where employees may work earth retaining systems submitted by vendors. adjacent to and above vertical faces of retaining DES-SD and DES-GS assist Headquarters walls, wingwalls, abutments, etc. where the Construction in evaluating the CRIP submitted by vertical fall is 4 feet or more. contractors. If cable railing is required on a wall which is less Districts may prepare contract plans, specifications, than 4 feet 6 inches tall and that wall is located and engineer's estimate for Standard Plan retaining within the clear recovery zone, then the cable walls provided the foundation conditions and site railing should be placed behind the wall. See requirements permit their use. A foundation Standard Plan B11-47 for details of cable railing. investigation is required for all reinforced earth slopes and earth retaining systems. PS&E’s for Special designs for safety railing may be slurry walls, deep soil mixing walls, gabion walls, considered where aesthetic values of the area tire anchored timber walls, salvaged material walls, warrant special treatment. In addition, if the and experimental walls will be prepared by the retaining wall is accessible to the public and will District PE with assistance from DES-GS. Earth have pedestrians or bicycles either above or below retaining systems may be included in the PS&E as the retaining wall, then the provisions of Index either highway or structure items. 208.10 shall apply. The time required for DES-SD to provide the Concrete barriers may be mounted on top of special design of a retaining system is site and retaining walls. Details for concrete barriers project dependent. Therefore, the request for a mounted on top of retaining walls Type 1 through 5 special design should be submitted by the District are shown in the Standard Plans. A concrete PE to DES-SD as far in advance as possible, but barrier slab is required if a concrete barrier is to be not less than 20 feetonths prior to PS&E delivery. used at the top of a special design earth retaining At least 3 months is required to conduct a system. DES-SD should be contacted for foundation investigation for an earth retaining preparation of the plans involved in the special system. A site plan, index map, cross sections, design. vertical and horizontal alignment, and utility and Retaining walls joining right of way fences should drainage requirements should be sent along with be a minimum of 6 feet clear height. the request. The District PE should examine the proposed DES-GS has the responsibility for preparing a retaining wall location in relation to the provisions feasibility study for AERS. The District PE should of Index 309.1 to ensure adequate horizontal submit project site information (site plans, typical clearances to the structure or to determine the type sections, etc.) as early in the planning stage as and placement of the appropriate roadside safety possible so that determination of the most devices.

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appropriate earth retaining system to use can be Any log of test boring sheets accompanying made. the foundation reports must be included with the contract plans as project information, for 210.8 Guidelines for Type Selection and the bidders use. Plan Preparation (3) Earth Retaining Systems with Standard Plans. (1) Type Selection. Type selection for reinforced The following guidelines should be used to earth slopes and earth retaining systems prepare the contract plans for earth retaining should be based on considerations set forth in systems, which are found in the Standard Index 210.2. Plans: The District PE should request a feasibility (a) Loads. All wall types selected must be study for a reinforced slope or earth retaining capable of supporting the field surcharge system from DES-GS as early as possible in conditions. The design surcharges can be the project development process. After the found in the Standard Plans. Deviance feasibility study, the District PE should from these loadings will require a special request an Advanced Planning Study (APS) design from DES-SD for all special design earth (b) Footing Steps. For economy and ease of retaining systems that DES-SD may be construction of wall Types 1 through 6, required to include in the PS&E. the following criteria should be used for If the District PE decides that the course of layout of footing steps. action favors an earth retaining system in • Distance between steps should be in which the PS&E will be delivered by DES- multiples of 8 feet. SD, then a Bridge Site Data Submittal – Non- Standard Retaining Wall/Noise Barrier must • A minimum number of steps should be be submitted to DES-Structure Design used even if a slightly higher wall is Services & Earthquake Engineering – necessary. Small steps, less than 1 foot Preliminary Investgations (PI) Branch. A in height, should be avoided unless the copy of this submittal will be forwarded to distance between steps is 96 feet or DES-SD and DES-GS by PI. more. The maximum height of steps should be held to 4 feet. If the footing The Structure PE, with input from DES-GS thickness changes between steps, the and the District PE, will then type select the bottom of footing elevation should be appropriate earth retaining system for the site adjusted so that the top of footing and project. After an earth retaining system remains at the same elevation. has been type selected, then DES-GS will prepare a Geotechnical Design Report. (c) Sloping Footings. The following criteria should be used for layout of sloping The process for type selecting and developing footings. the PS&E for reinforced earth slopes and earth retaining systems is set forth in Figure 210.8. • The maximum permissible slope for reinforced concrete retaining walls is All appropriate State designed and proprietary 3 percent. Maximum footing slope earth retaining systems should be considered for masonry walls is 2 percent. for inclusion in the contract documents to promote competitive bidding, which can result • When sloping footings are used, form in cost savings. and joint lines are permitted to be perpendicular and parallel to the (2) Foundation Investigations. DES-GS should footing for ease of construction. be requested to provide a foundation recommendation for all sites involving a • In cases where vertical electroliers or reinforced slope or an earth retaining system. fence posts are required on top of a

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wall, the form and joint lines must alignment or areas between return walls also be vertical. A sloping footing must be drained by downspouts passing should not be used in this situation through the walls. Standard Plan B3-9 since efficiency of construction shows typical drainage details. Special would be lost. design of surface water drainage facilities may be necessary depending on the Sloping footing grades should be constant amount of surface water anticipated. for the entire length of the wall. Breaks in Where ground water is likely to occur in footing grade will complicate forming and any quantity, special provisions must be result in loss of economy. If breaks in made to intercept the flow to prevent footing grade are necessary, a level inundation of the backfill and unsightly stepped footing should be used for the continuous flow through weep holes. entire wall. (f) Quantities. When the AERS procedure is • When the top of wall profile of crib not utilized, quantities for each wall item walls is constant for the entire length, of work are usually developed for the bottom of wall profile may be payment. The quantities for concrete, sloped to avoid steps in the top of expansion joint waterstop, structure wall. In this case, all steps to excavation, structure backfill, pervious compensate for changes of wall backfill material, concrete barrier or height and original ground profile railing, and gutter concrete must also be would be made in the bottom of wall. tabulated. Quantities should be tabulated The maximum permissible slope is 6 on the plans for each wall. percent. If vertical electroliers or fence posts are required on top of the (4) Soil Reinforcement Systems. The following wall, the crib wall should not be guidelines should be used to prepare the sloped. Sloping crib walls are contract plans for soil reinforcement systems: permissible with guard railing with (a) Leveling Pads. Most soil reinforcement vertical posts. systems do not require extensive foundation preparation. It may be (d) Wall Joints. General details for required necessary, however, to design a concrete wall joints on wall Types 1, 1A, 2, and 5 leveling pad on which to construct the face are shown on Standard Plan B0-3. elements. A reinforced concrete leveling Expansion joints, Bridge Detail 3-3, pad will be required in areas prone to should be shown at maximum intervals of consolidation or frost disturbance. 96 feet. Shorter spaces should be in multiples of 8 feet. Expansion joints • Steps in the leveling pad should be the generally should be placed near angle same height as the height of the facing points in the wall alignment. When elements or thickness of the soil layer concrete barriers are used on top of between the soil reinforcement. retaining walls, the waterstop in the • Distance between steps in the leveling expansion joint must be extended 6 inches pad should be in increments equivalent into the barrier. This detail should be to the length of individual facing shown or noted on the wall plans. elements. Weakened plane joints, Bridge Detail 3-2, should be shown at nearly equal spaces • A minimum number of steps should be between joints. used even if a slightly higher wall is necessary. (e) Drainage. Gutters should be used behind walls in areas where it is necessary to (b) Drainage. Gutters should be used behind carry off surface water or to prevent walls in areas where it is necessary to scour. Low points in wall vertical carry off surface water or to prevent

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scour. Low points in wall vertical DES-SD a complete cross section of the alignment or areas between return walls roadway at the sign and the layout and must be drained by downspouts passing profile of the earth retaining system. through the walls. Special design of (c) Fence and Railing Post Pockets. Post surface water drainage facilities will be pocket details shown for cable railing in necessary and should be prepared by the Standard Plans may also be used for DES-SD. Where ground water is likely to mounting chain link fence on top of occur in any quantity, special provisions retaining walls. Special details may be must be made to intercept the flow to necessary to accommodate the reinforce- prevent inundation of the backfill. ment in soil reinforcement systems. (c) Quantities. When the AERS procedure is (d) Return Walls. Return walls should be not utilized, quantities for each item of considered for use on the ends of the walls work are usually developed for payment. to provide a finished appearance. Return Bid items must include, but not be limited walls are necessary when wall offsets are to: excavation and backfill for the used or when the top of wall is stepped. embedment depth, soil reinforcement, Return walls for soil reinforcement systems facing elements, and concrete for leveling will require special designs to pad construction. Additional bid items for accommodate the overlapping of soil inclusion are any drainage system, reinforcing elements. pervious backfill, concrete barrier, railings, and concrete gutters. Quantities All special wall details such as sign bases, should be tabulated on the plans for each utility openings, drainage features, fences, wall. and concrete barriers should be shown on the plan sheet of the wall concerned or (5) Earth Retaining Systems. The following included on a separate sheet with the wall miscellaneous details are applicable to all plan sheets. Details should be cross- earth retaining systems: referenced on the wall sheets to the sheets (a) Utilities. Provisions must be made to on which they are shown. relocate or otherwise accommodate utilities

conflicting with the retaining wall. A utility opening for a Type 1 wall is shown on Standard Plan B3-9. Any other utility openings will require special design details and should be reviewed by DES-SD. (b) Electroliers and Signs. Details for mounting electroliers and signs on earth retaining systems are designed by DES-SD. Requests for preparation of details should be made at least 3 months in advance of the PS&E submittal to District Officer Engineer date. To accommodate the base plates for overhead signs, a local enlargement may affect the horizontal clearance to both the edge of pavement and the right of way line. This type of enlargement should be considered at the time of establishing the wall layout and a need for a Mandatory Design Exception determined. For mounting details, furnish

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Figure 210.8 Type Selection and PS&E Process for Reinforced Earth Slopes and Earth Retaining Systems