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S > 221hh > Where: L= Length of vertical curve (ft) S= Sight distance (ft) A= Algebraic difference in grades (%) > h1= Eye height (3.50 ft) > h2= Object height— see text (ft) Sight Distance, Crest Vertical Curve > Figure 650-4 When SL ASL > 221 200 2 hh A 100 2LS2 > 21 hh > When S 2212200 hh > AS L > A200L S > ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
difference in grades. The sight distance greater than the length of curve equation is not used in Figure 650-1 2. When the sight distance is greater than the length of curve and the length of curve is critical, the S>L equation given in Figure 650-5 may be used to find the minimum length of curve. When a new sag vertic...	{ "page_id": null, "source": 7320, "title": "from dpo" }
Distance, Sag Vertical Curve > Figure 650-5 Where: L = Curve length (ft) A = Algebraic grade difference (%) S = Sight distance (ft) Sight Distance, Sag Vertical Curve Figure 650-5 (5) Horizontal Curves Use Figure 650-13 a or the equation in Figure 650-7 to check for adequate stopping sight distance where sight obstruct...	{ "page_id": null, "source": 7320, "title": "from dpo" }
a roadside object is a sight obstruction.) When evaluating an existing roadway, see 650.04(7) . > »¼º«¬ª¸¹·¨©§RS28.65 cos RM1 »¼º«¬ª ¸¹·¨©§ RMRcos 28.65 RS 1‑ Sight Distance, Horizontal Curves > Figure 650-7 > »¼º«¬ª¸¹·¨©§RS28.65 cos RM1 »¼º«¬ª ¸¹·¨©§ RMRcos 28.65 RS 1‑ Sight Distance, Horizontal Curves > Figure ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
being reconstructed, existing stopping sight distance values in Figure 650-8 may be used. The minimum length of an existing sag vertical curve may be found using the equations in Figure 650-5, or using the K S values from Figure 650-8. In some cases, when continuous illumination is provided, a lesser length may be allo...	{ "page_id": null, "source": 7320, "title": "from dpo" }
encroachment on the opposing lane. • The distance the passing vehicle travels in the opposing lane. • The distance that an opposing vehicle travels during two-thirds of the time the passing vehicle is in the opposing lane. • A clearance distance between the passing vehicle and the opposing vehicle at the end of the pas...	{ "page_id": null, "source": 7320, "title": "from dpo" }
are not a restriction to passing sight distance. (3) Horizontal Curves Passing sight distance can be restricted on the inside of a horizontal curve by roadside objects that are 3.50 feet or more above the roadway surface. Use the distance from Figure 650-9 and the equation in Figure 650-7 to determine whether the objec...	{ "page_id": null, "source": 7320, "title": "from dpo" }
include interchanges; intersections; changes in cross section (such as at toll plazas and drop lanes); and areas of concentrated demand where sources of information compete (for example, those from roadway elements, traffic, traffic control devices, and advertising signs). If possible, locate these highway features whe...	{ "page_id": null, "source": 7320, "title": "from dpo" }
Curve, L (ft) Algebraic Differance in Grade, A (%) > 30 mph, S=200 ft 35 mph, S=250 ft 40 mph, S=305 ft 45 mph, S=360 ft 50 mph, S=425 ft 55 mph, S=495 ft 60 mph, S=570 ft 65 mph, S=645 ft 70 mph, S=730 ft 75 mph, S=820 ft 80 mph, S=910 ft The minimum length can also be determined by multiplying the algebraic differenc...	{ "page_id": null, "source": 7320, "title": "from dpo" }
mph, S=495 ft 60 mph, S=570 ft 65 mph, S=645 ft 70 mph, S=730 ft 75 mph, S=820 ft 25 mph, S=155 ft 35 mph, S=250 ft 80 mph, S=910 ft The minimum length can also be determined by multiplying the algebraic difference in grades by the K S value from Figure 650-1 (L=K S*A). Both the figure and equation give approximately t...	{ "page_id": null, "source": 7320, "title": "from dpo" }
70 mph, S=730 ft 75 mph, S=820 ft 35 mph, S=250 ft 80 mph, S=910 ft 2.00 ft and 2.75 ft above the center-Design Manual M 21-01 Sight Distance May 2006 Page 650-11 Horizontal Stopping Sight Distance > Figure 650-13b When ¸¸¹·¨¨©§ ! > s > o ½C 0.75X 2h , roadside object is a sight obstruction. Where: M = Lateral clearan...	{ "page_id": null, "source": 7320, "title": "from dpo" }
7000 8000 9000 10,000 Length of Vertical Curve, L (ft) Algebraic Differance i n Gr ade, A (%) > 25 mph, S=900 ft 30 mph, S=1090 ft 35 mph, S=1280 ft 40 mph, S=1470 ft 45 mph, S=1625 ft 50 mph, S=1835 ft 55 mph, S=1985 ft 70 mph, S=2480 ft 60 mph, S= 2135 ft 65 mph, S=2285 ft Where S>L A2800 ‑2S L A1400 2LS Where S A2...	{ "page_id": null, "source": 7320, "title": "from dpo" }
to accident severity when selecting a mitigative measure. Use traffic barriers only when other measures cannot reasonably be accomplished. See Chapter 710 for additional information on traffic barriers. ## 700.02 References A Policy on Geometric Design of Highways and Streets (Green Book), AASHTO, 2001 Revised Code of ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
vehicle will continue until it reaches the bottom, without having the ability to recover control. Fill slopes steeper than 4H:1V, but no steeper than 3H:1V, are considered nonrecoverable. recoverable slope A slope on which the driver of an errant vehicle can regain control of the vehicle. Slopes of 4H:1V or flatter are...	{ "page_id": null, "source": 7320, "title": "from dpo" }
placement of a new fixed object on the roadside or median. Use the Design Clear Zone Inventory form (Figures 700-2a & 2b) to identify potential hazards and propose corrective actions. Guidance for establishing the Design Clear Zone for highways outside of incorporated cities is provided in Figure 700-1. This guidance a...	{ "page_id": null, "source": 7320, "title": "from dpo" }
Towns For managed access state highways within an urban area, it is recognized that in many cases it will not be practical to provide the Design Clear Zone distances shown in Figure 700-1. Roadways within an urban area generally have curbs and sidewalks and might have objects such as trees, poles, benches, trash cans, ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
slopes are defined as nonrecoverable slopes. A vehicle might be able to begin recovery on the shoulder, but will be unable to further this recovery until reaching a flatter area (4H:1V or flatter) at the toe of the slope. Under these conditions, the Design Clear Zone distance is called a recovery area. The method used ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
consideration: • Locations with high accident rate histories. • Locations with pedestrian and bicycle usage. See Chapters 1020, “Bicycle Facilities,” and 1025, “Pedestrian Design Considerations.” Roadside Safety Design Manual Page 700-4 May 2006 • Playgrounds, monuments, and other locations with high social or economic...	{ "page_id": null, "source": 7320, "title": "from dpo" }
ADT and height of fill intersect on the “Barrier Recommended” side of the embankment slope curve, then provide a barrier if flattening the slope is not feasible or cost effective. Do not use Figure 700-5 for slope design. Design guidance for slopes is in Chapters 430 and 640. Also, if the figure indicates that barrier ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
• Wooden poles or posts with cross sectional area greater than 16 square inches that do not have breakaway features. • Nonbreakaway steel sign posts. • Nonbreakaway light standards. • Trees having a diameter of 4 inches or more measured at 6 inches above the ground surface. Design Manual Roadside Safety May 2006 Page 7...	{ "page_id": null, "source": 7320, "title": "from dpo" }
inches to 4 feet if requested by the mail carrier. If the desired height is to be different from 3 feet 3 inches provide the desired height in the contract plans. See Figure 700-6 for installation guidelines. In urban areas where sidewalks are prevalent, contact the postal service to determine the most appropriate mail...	{ "page_id": null, "source": 7320, "title": "from dpo" }
verify these conditions. If debris drift is a concern, consider options to reduce the amount of debris that can enter the pipe. (See the Hydraulics Manual ). Other treatments are extending the culvert to move the end outside the Design Clear Zone or installing a traffic barrier. Roadside Safety Design Manual Page 700-6...	{ "page_id": null, "source": 7320, "title": "from dpo" }
generally not an option. However, since speeds near signals are generally lower, the potential for a severe impact is reduced. For these reasons, the only mitigation is to locate the support as far from the traveled way as possible. In locations where signals are used for ramp meters, the supports can be made breakaway...	{ "page_id": null, "source": 7320, "title": "from dpo" }
by an errant vehicle must be considered for mitigation on a project-by-project basis. Consider the length of time traffic is exposed to this hazard and its location in relationship to other highway features such as curves. Analyze the potential motorist risk and the benefits of treatment of bodies of water located with...	{ "page_id": null, "source": 7320, "title": "from dpo" }
a curve to provide the required stopping sight distance. When median barrier is being placed in an existing median, identify the existing crossovers and enforcement observation points. Provide the necessary median crossovers in accordance with Chapter 960, considering enforcement needs. Chapter 1050 provides guidance o...	{ "page_id": null, "source": 7320, "title": "from dpo" }
present. Where bicycle travel is allowed, discontinue SRS at locations where shoulder width reductions can cause bicyclists to move into or across the area where rumble strips would normally be placed, such as shoulders adjacent to bridges with reduced shoulder widths. SRS patterns vary depending on the likelihood of b...	{ "page_id": null, "source": 7320, "title": "from dpo" }
comfort and control of bicycle riders; consequently, their use is to be limited to highway corridors that experience high levels of run-off-the-road accidents. Apply the following criteria in evaluating the appropriateness of rumble strips on the shoulders of undivided highways. • Use on rural roads only. • Ensure shou...	{ "page_id": null, "source": 7320, "title": "from dpo" }
process. Consult the following web site for guidance on conducting an engineering analysis: > RoadsideSafety/Chapter700/Chapter700B.htm Design Manual Roadside Safety May 2006 Page 700-9 (c) Centerline rumble strips are placed on the centerline of undivided highways to alert drivers that they are entering the opposing ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
adequacies. • Centerline rumble strips are not appropriate where two-way left-turn lanes exist. (2) Headlight Glare Considerations Headlight glare from opposing traffic can cause safety problems. Glare can be reduced by the use of wide medians, separate alignments, earth mounds, plants, concrete barrier, and by glare s...	{ "page_id": null, "source": 7320, "title": "from dpo" }
Safety Design Manual Page 700-10 May 2006 • At an interchange where an on-ramp merges with a collector distributor and the ramp traffic might be unable to distinguish between collector and main line traffic. In this instance, consider other solutions, such as illumination. • Where headlight glare is a distraction to ad...	{ "page_id": null, "source": 7320, "title": "from dpo" }
15 15 15 15 15 15 * 19 18 17 16 15 Under 250 11 11 11 11 11 11 * 16 14 13 12 11 251-800 12 12 13 13 13 13 * 18 16 14 14 13 45 801-2000 13 13 14 14 14 14 * 20 17 16 15 14 2001-6000 15 15 16 16 16 16 * 22 19 17 17 16 Over 6000 16 16 17 17 17 17 * 24 21 19 18 17 Under 250 11 12 13 13 13 13 * 19 16 15 13 13 251-800 13 14 1...	{ "page_id": null, "source": 7320, "title": "from dpo" }
20 22 22 24 24 * 38 31 29 26 25 65 801-2000 19 22 24 25 26 27 * 41 34 31 29 28 2001-6000 20 25 27 27 29 30 * 46 37 35 32 31 Over 6000 22 27 29 30 31 32 * 50 41 38 34 33 Under 250 16 19 21 21 23 23 * 36 29 27 25 24 251-800 18 22 23 24 26 26 * 41 33 31 28 27 70 801-2000 20 24 26 27 28 29 * 45 37 34 31 30 2001-6000 22 27 ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
Way Description Corrective Actions Considered (2) Estimated Cost to Correct Correction Planned (1) Yes No L R > (1) Only one “Yes” or “No” per item number. Corrections not planned must be explained on reverse side. > (2) A list of Location 1 & 2 Utility Objects to the forwarded to the region Utility Office for coordina...	{ "page_id": null, "source": 7320, "title": "from dpo" }
ee t horizontal beyond beginning of back slope Design Clear Zone = 19 f eet Case 2 Cut section with ditch (fore slope 3H:1V or steeper and back slope not steeper than 3H:1V) Conditions: Speed - 45 mph Traffic - 3000 ADT Foreslope - 2H:1V Back slope 4H:1V Criteria: Use recovery area formula Recovery Area = (shoulder wid...	{ "page_id": null, "source": 7320, "title": "from dpo" }
Recovery Area = (shoulder width) + (horizontal distance) + (Design Clear Zone distance - > Design Clear Zone = 23 ft Edge of traveled way 4H:1V 3H:1V 8 ft 6 ft shld 3 ft > Design Clear Zone = 19 ft Edge of traveled w ay 3H:1V 2H:1V 10 ft 6ft 3ft shld Recovery Area = 21 ft Edge of traveled way 2H:1V 4H:1V 6 ft 6 ft shld...	{ "page_id": null, "source": 7320, "title": "from dpo" }
720.03 Selection 720.04 Documentation ## 720.01 Impact Attenuator Systems Impact attenuator systems are protective systems that prevent an errant vehicle from impacting a hazard by either gradually decelerating the vehicle to a stop when hit head-on or by redirecting it away from the hazard when struck on the side. The...	{ "page_id": null, "source": 7320, "title": "from dpo" }
The system uses a brake and cable device for head-on impacts and for redirection. The cable is embedded in a concrete anchor at the end of the system. 4. Foundation: A concrete foundation is not required for this system, but a paved surface is recommended. 5. Slope: 10H:1V or flatter slope between the edge of the trave...	{ "page_id": null, "source": 7320, "title": "from dpo" }
two cables running longitudinally through the system and attached to foundations at each end of the system. (See Figure 720-2c.) 3. Function: Overlapping panels, structural support diaphragms, cable supports, cables, and foundation anchors allow the system to resist angled impacts and mitigate head-on impacts. 4. Found...	{ "page_id": null, "source": 7320, "title": "from dpo" }
shape when the system is reset. It is anticipated that this system will require very few replacement parts or extensive repair. 4. Foundation: The system is installed on a concrete foundation. 5. Slope: If the site has excessive grade or cross slope, additional site preparation or modification to the units in accordanc...	{ "page_id": null, "source": 7320, "title": "from dpo" }
to 10 feet wide. 2. Description: The system consists of polyethylene cylinders with varying wall thickness, internal struts, space frame diaphragms, and a monorail. (See Figure 720-2d.) 3. Function: When hit head-on, the cylinders compress, absorb the impact energy, and immediately return to much of their original shap...	{ "page_id": null, "source": 7320, "title": "from dpo" }
not appropriate where high angle impacts are likely. Impact Attenuator Systems Design Manual M 22-01 Page 720-4 May 2006 4. Foundation : A concrete or paved surface is recommended. 5. Slope : If the site has excessive grade or cross slope, additional site preparation or modification to the units in accordance with the ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
and in Figure 720-5: (a) ABSORB 350 1. Purpose: The ABSORB 350 is an end treatment limited to temporary installations for both concrete barrier and the Quickchange Moveable Barrier (QMB). 2. Description: The system contains water-filled Energy Absorbing Elements. Each element is 2 feet wide, 2 feet 8 inches high, and 3...	{ "page_id": null, "source": 7320, "title": "from dpo" }
units in accordance with the manufacturer’s literature is required. Excessive is defined as steeper than 8% for the ADIEM 350. 6. Manufacturer/Supplier: Trinity Industries, Inc. (c) QuadGuard CZ This system is like the permanent QuadGuard listed for permanent systems above except that it can be installed on a 6-inch-mi...	{ "page_id": null, "source": 7320, "title": "from dpo" }
face) is positioned over the upstream end of the guidance tracks and contains a hardened steel blade that cuts the metal plates on the sides of the guidance tracks as it is forced backward when hit head-on. 4. Foundation: The system requires a concrete foundation. 5. Slope: 10H:1V or flatter slope between the edge of t...	{ "page_id": null, "source": 7320, "title": "from dpo" }
barriers. (See Figure 720-4a.) (b) TREND The TREND is an end treatment with a built-in transition and was used at the end of rigid barriers including bridge rails. The system is similar to the QuadTrend 350 except that it uses thrie beam fender panels. (See Figure 720-4a.) (c) G-R-E-A-T (Guard Rail Energy Absorption Te...	{ "page_id": null, "source": 7320, "title": "from dpo" }
and deformation. When impacted from the side, the QUEST System restrains lateral movement by dynamic tension developed between the end restraints. Design Manual M 22-01 Impact Attenuator Systems May 2006 Page 720-7 (d) Low Maintenance Attenuator System (LMA) The LMA is an end treatment for concrete barrier and beam gua...	{ "page_id": null, "source": 7320, "title": "from dpo" }
all existing curbing be removed and the surface smoothed with asphalt or cement concrete pavement before an impact attenuator is installed. However, curbs 4 inches or less in height may be retained depending on the practicality of their removal. In general, attenuators are aligned parallel to the roadway except the ine...	{ "page_id": null, "source": 7320, "title": "from dpo" }
impact rate. If few impacts are anticipated, lower-cost devices such as inertial barriers might meet the need. Inertial barriers have the lowest initial cost and initial site preparation. However, maintenance will be costly and necessary after every impact. Labor and equipment are necessary to clean up the debris and i...	{ "page_id": null, "source": 7320, "title": "from dpo" }
is to be used as a starting point. As the considerations discussed previously are analyzed, inappropriate systems may be identified and eliminated from further consideration. Systems that are not eliminated may be appropriate for the project. When the site conditions vary, it might be necessary to have more than one li...	{ "page_id": null, "source": 7320, "title": "from dpo" }
350 Inertial Barrier Impact Attenuator Systems – Permanent Installations Figure 720-2d REACT 350 Wide Design Manual M 22-01 Impact Attenuator Systems May 2006 Page 720-13 Impact Attenuator Systems – Permanent Installations Figure 720-2e SCI100GM / SCI70GM Impact Attenuator Systems Design Manual M 22-01 Page 720-14 May ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
T 2.75-3.25 13.1-22.1 N 3.3 C (5) N-E-A-T(8) T 1.9 9.7 N (3) A(5) TRACC (12) T 2.6 21.3 N 8 BTriton CET (9) T 1.8 40 N (3) AQUEST T 2.8 22.2 Y 3.5 B Impact Attenuator Comparison > Figure 720-5a Design Manual M 22-01 Impact Attenuator Systems May 2006 Page 720-19 1) A ($5,000 to $10,000); B ($10,000 to $15,000); C ($15,...	{ "page_id": null, "source": 7320, "title": "from dpo" }
given dimension is the approximate outside width of each system. In most cases, this width is slightly wider than the effective width. To determine the width of an object that may be shielded refer to the manufacture’s specifications. (See the WSDOT Design Policy, Standards, & Safety Research Unit web site for links to...	{ "page_id": null, "source": 7320, "title": "from dpo" }
be justified if the existing delineation is unaffected by construction and an evaluation of accident rates clearly shows that delineation is not a contributing factor. It is important to maintain an adequate level of retroreflectivity for both traffic signs and traffic markings to enhance safety for motorists during ho...	{ "page_id": null, "source": 7320, "title": "from dpo" }
Page 830-2 May 2006 mcd/m 2/lux Pavement marking retroreflectivity is represented by the coefficient of retroreflected luminance (R L) measured in millicandelas per square meter. mil Unit of measurement equivalent to 0.001 inches. MUTCD Manual on Uniform Traffic Control Devices. pavement marking A colored marking appli...	{ "page_id": null, "source": 7320, "title": "from dpo" }
applicable), and edge lines (except as noted), are required on all paved state highways, unless an exception is granted by the State Traffic Engineer with justification. Guidelines for the application of various pavement markings are provided in the Standard Plans and the MUTCD. (a) Longitudinal pavement markings defin...	{ "page_id": null, "source": 7320, "title": "from dpo" }
2006 Page 830-3 drop lane line A wide broken white line used in advance of a wide line to delineate a lane that ends at an off-ramp or intersection. edge line A solid white or yellow line used to define the outer edges of the traveled way. Edge lines are not required where curbs or sidewalks are 4 feet or less from the...	{ "page_id": null, "source": 7320, "title": "from dpo" }
and high occupancy vehicle (HOV) lanes, or business access and transit (BAT) lanes, bike lanes, and other preferential lanes where crossing is discouraged. (b) Transverse pavement markings define pedestrian crossings and vehicle stopping points at intersections. They are also used to warn the motorist of approaching co...	{ "page_id": null, "source": 7320, "title": "from dpo" }
line used to indicate the stopping point at an intersection or railroad crossing. traffic arrow A white marking used in storage lanes and two-way left-turn lanes to denote the direction of turning movement. Arrows are also used at ramp terminals and intersections on divided highways to discourage wrong-way movements. D...	{ "page_id": null, "source": 7320, "title": "from dpo" }
the marking. For the recommended pavement marking material for different highway types and snow removal practices, see Figure 830-1. Consult with the region’s Traffic Office and Maintenance Office to select the best material for the project. (a) Paint. Paint is the most common pavement marking material. It is relativel...	{ "page_id": null, "source": 7320, "title": "from dpo" }
They can, however, be a more cost-effective measure than paint because of their longer service life. Plastic marking materials may provide a year-round retroreflective pavement marking, while paint may not last until the next restriping. Plastic marking materials currently listed in the Standard Specifications include ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
Tape. Preformed tape is composed of thermoplastic or other materials that are fabricated under factory conditions. After curing, the material is cut to size and shipped to the work site in rolls or in flat pieces. The material is then applied to the roadway with an adhesive on the underside of the tape. Preformed tape ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
range of 40º to 105º Fahrenheit, provided the pavement surface is dry. The material can be used for both transverse and longitudinal applications. The material can also be applied with bumps (Type D profiled) that slightly enhance wet night retroreflectivity. The bumps also produce the rumble effect similar to raised p...	{ "page_id": null, "source": 7320, "title": "from dpo" }
are applied directly to the pavement surface. In steel bit snow plowing areas, the pavement markings may be inlaid or grooved to protect the markings. Pavement markings, because they are higher than the surrounding pavement surface, are subject to rapid wear caused by traffic and snowplows. As they wear, they lose visi...	{ "page_id": null, "source": 7320, "title": "from dpo" }
to 250 mils deep and 4 inches wide. Coordinate with the region’s Traffic Office on the use and dimensions of grooved plastic line marking. (4) Raised Pavement Markers Raised Pavement Markers (RPMs) are installed as positioning guides with long line pavement markings. They can also be installed as a complete substitutio...	{ "page_id": null, "source": 7320, "title": "from dpo" }
installed in a groove ground into the pavement in accordance with the Standard Plans. RRPMs provide guidance similar to RPMs in ice chisel and steel blade snow removal areas. RRPMs can also be used in rubber blade snow removal areas in accordance with region policy. RRPMs, when specified, are installed at the locations...	{ "page_id": null, "source": 7320, "title": "from dpo" }
both sides, and green reflective sheeting below the silver-white sheeting on the side facing traffic. They are used at intersections of undivided highways without illumination. (f) Type G2 guideposts have silver-white reflective sheeting on both sides, and green reflective sheeting below the silver-white reflective she...	{ "page_id": null, "source": 7320, "title": "from dpo" }
to mark obstructions within or adjacent to the roadway. The MUTCD details three types of object markers. The Type 3 object marker with yellow and black sloping stripes is the most commonly used object marker. The MUTCD contains criteria for the use of object markers to mark objects in the roadway and objects adjacent t...	{ "page_id": null, "source": 7320, "title": "from dpo" }
Paint Collector Paint Paint Paint Paint Paint Steel Blade Snow Removal Areas Roadway Classification Marking Type (3) Centerlines (5) Lane Lines (5) Edge Lines Wide Lines Transverse Markings Interstate-Urban N.A. Plastic (2) Paint or Plastic (2) Paint or Plastic (2) Paint or Plastic (2) Interstate-Rural N.A. Paint Paint...	{ "page_id": null, "source": 7320, "title": "from dpo" }
illuminated sections. (6) PMMA refers to profiled methyl methacrylate. (7) Consult region striping policy. (8) FMMA refers to flat methyl methacrylate. Pavement Marking Material Guide Figure 830-1 Delineation Design Manual M 22-01 Page 830-10 May 2006 Highway Type Guideposts on Tangents (See Notes 1 & 3) Guideposts on ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
or less from the roadway. Use delineator spacing > of 40 feet or less. Guidepost Placement > Figure 830-2 Design Manual M 22-01 Intersections At Grade May 2006 Page 910-1 910.01 General 910.02 References 910.03 Definitions 910.04 Design Considerations 910.05 Design Vehicle 910.06 Right-Turn Corners 910.07 Channelizatio...	{ "page_id": null, "source": 7320, "title": "from dpo" }
of Highways and Streets (Green Book), 2001, AASHTO Guidelines and Recommendations to Accommodate Older Drivers and Pedestrians ,FHWA-RD-01-051 , USDOT, FHWA, May 2001 Highway Capacity Manual (HCM), Special Report 209, Transportation Research Board, National Research Council Highway Research Record No. 211 Aspects of Tr...	{ "page_id": null, "source": 7320, "title": "from dpo" }
(T) intersection An intersection with three legs in the general form of a “T.” split tee A four leg intersection with the cross road intersecting the through roadway at two tee intersections. The crossroad must be offset at least the width of the roadway. wye (Y) intersection An intersection with three legs in the gene...	{ "page_id": null, "source": 7320, "title": "from dpo" }
and traffic service vehicles. (See Chapter 960.) roundabout A circular intersection at which all traffic moves counterclockwise around a central island. (See Chapter 915) rural intersection An intersection in a nonurban area. Design Manual M 22-01 Intersections At Grade May 2006 Page 910-3 urban intersection An interse...	{ "page_id": null, "source": 7320, "title": "from dpo" }
Existing intersections with an intersection angle between 60° and 120° may remain. Intersection angles outside this range tend to restrict visibility, increase the area required for turning, increase the difficulty to make a turn, increase the crossing distance and time for vehicles and pedestrians, and make traffic si...	{ "page_id": null, "source": 7320, "title": "from dpo" }
to the right less than the required intersection spacing [see 910.04(4)] unless traffic is restricted to right-in right-out only. Intersections At Grade Design Manual M 22-01 Page 910-4 May 2006 (d) Other Nonstandard Configurations. Do not design intersections with nonstandard configurations such as: • Intersections wi...	{ "page_id": null, "source": 7320, "title": "from dpo" }
provide for safety and the desired operational characteristics for the highway. The minimum spacing for highways with limited access control is covered in Chapter 1430. For other highways, the minimum spacing is dependent on the Highway Access Management Class. See Chapter 1435 for minimum intersection spacing on Manag...	{ "page_id": null, "source": 7320, "title": "from dpo" }
impacts include possible capacity reductions and greater speed differences between turning vehicles and through vehicles. Select a design vehicle that is the largest vehicle that normally uses the intersection. The primary use of the design vehicle is to determine radii requirements for each leg of the intersection. It...	{ "page_id": null, "source": 7320, "title": "from dpo" }
than the design vehicle are allowed and are anticipated to occasionally use the intersection make certain that they can make the turn without leaving the paved shoulders or encroaching on a sidewalk. The amount of encroachment allowed is dependent on the frequency of the vehicle and the resulting disruption to other tr...	{ "page_id": null, "source": 7320, "title": "from dpo" }
taper or large radius curve at the beginning of the turn and a small radius curve at the end. This allows larger islands while forcing the turning traffic to slow down. Figure 910-7 shows right-turn corner designs for the design vehicles. These are considered the minimum pavement area to accommodate the design vehicles...	{ "page_id": null, "source": 7320, "title": "from dpo" }
left-turn lanes, consider impacts to all intersection movements and users. At signalized intersections, use a traffic signal analysis to determine if a left-turn lane is needed and what the storage requirements are. (See Chapter 850.) At unsignalized intersections, use the following as a guide to determine whether or n...	{ "page_id": null, "source": 7320, "title": "from dpo" }
the 4-foot clearance may remain with split signal phasing, an evaluate upgrade, and concurrence from the HQ Traffic Office. Where one-way left-turn channelization with curbing is to be provided, ensure that surface water will drain. Provide illumination at left-turn lanes in accordance with the guidelines in Chapter 84...	{ "page_id": null, "source": 7320, "title": "from dpo" }
be provided where the median is 23 f ee t or wider. The median acceleration lane might not be necessary at a signalized intersection. When a median acceleration lane is to be used, design it in accordance with 910.07(3) Speed Change Lanes. Where medians have sufficient width, provide a 2-foot shoulder adjacent to a lef...	{ "page_id": null, "source": 7320, "title": "from dpo" }
of traffic. However, they do not provide a safe refuge for pedestrians and can encourage strip development with additional closely spaced access points. Consider other alternatives, before using a TWLTL, such as prohibiting midblock left-turns and providing for U-turns. See Chapters 440 and 1435 for additional restrict...	{ "page_id": null, "source": 7320, "title": "from dpo" }
capacity analysis may be used to determine if right-turn lanes are necessary to maintain the desired level of service. Where adequate right of way exists, providing right-turn lanes is relatively inexpensive and can provide increased safety and operational efficiency. The right-turn pocket or the right-turn taper (Figu...	{ "page_id": null, "source": 7320, "title": "from dpo" }
provided on other through roadways. Justification for a speed change lane depends on many factors such as speed, traffic volumes, capacity, type of highway, the design and frequency of intersections, and accident history. A deceleration lane is advantageous because, if a deceleration lane is not provided the driver lea...	{ "page_id": null, "source": 7320, "title": "from dpo" }
design of the intersection as necessary to allow for vehicle tracking. Reducing the shoulder width at intersections facilitates the installation of turn lanes without unduly affecting the overall width of the roadway. A narrower roadway also reduces pedestrian exposure in crosswalks and discourages motorists from using...	{ "page_id": null, "source": 7320, "title": "from dpo" }
are for islands with vertical curbs 6 inches or higher. Where painted islands are used, such as in rural areas, these widths are desirable but may be omitted. See Chapter 641 for turning roadway widths. Island markings may be supplemented with reflective raised pavement markers. Barrier-free access must be provided at ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
the use of curbs. ## 910.08 Roundabouts Modern roundabouts are circular intersections. They can be an effective intersection type. Modern roundabouts differ from the old rotaries and traffic circles in two important respects: they have a smaller diameter, which lowers speeds; and they have splitter islands that provide...	{ "page_id": null, "source": 7320, "title": "from dpo" }
arterial intersects a collector or local road. See Chapter 915 for information and requirements on the design of roundabouts. ## 910.09 U-Turns For divided highways without full access control that have access points where a median prevents left turns, consider providing locations designed to allow U-turns. Normally, t...	{ "page_id": null, "source": 7320, "title": "from dpo" }
react accordingly. Provide decision sight distance, where practical, in advance of stop signs, traffic signals, and roundabouts. See Chapter 650 for guidance. The driver of a vehicle that is stopped, waiting to cross or enter a through roadway, needs obstruction-free sight triangles in order to see enough of the throug...	{ "page_id": null, "source": 7320, "title": "from dpo" }
WB-67 rather than the SU. In areas where SU or WB vehicles are minimal, and right of way restrictions prohibit adequate sight triangle clearing, only the P vehicle need be considered. At existing intersections, when sight obstructions within the sight triangle cannot be removed due to limited right of way, the intersec...	{ "page_id": null, "source": 7320, "title": "from dpo" }
periodic scheduled maintenance of vegetation in the sight triangle within the WSDOT right of way or state maintenance easement. At intersections controlled by traffic signals, provide sight distance for right-turning vehicles. Designs for movements that cross divided highways are influenced by the median widths. If the...	{ "page_id": null, "source": 7320, "title": "from dpo" }
assign right of way through the use of traffic control devices to maximize capacity for all users of the intersection. Turn prohibitions may be used to increase intersection capacity. • Reduce Conflict Points. The crossing, converging, and diverging of traffic creates conflicts which increase the potential for accident...	{ "page_id": null, "source": 7320, "title": "from dpo" }
generators adjacent to an interchange, width for a median on the local road is desirable whenever such development is believed imminent. This allows for future left-turn channelization. Use median channelization when justified by capacity determination and analysis, or by the need to provide a smooth traffic flow. Dete...	{ "page_id": null, "source": 7320, "title": "from dpo" }
for Approval Check List on the following web site: > default.htm (3) Local Agency or Developer Initiated Intersections There is a separate procedure for local agency or developer-initiated projects at intersections with state routes. The project initiator submits an intersection plan, and the documentation of design c...	{ "page_id": null, "source": 7320, "title": "from dpo" }
storage lane and the median acceleration lane. (2) For left-turn storage length, see Figures 910-8b for 4-lane roadways or 9a throug9c for 2-lane roadways. (3) Desirable radius not less than 50 ft. Use templates to verify that the design vehicle can make the turn. (4) See Figure 910-7 for right-turn corner design. (5) ...	{ "page_id": null, "source": 7320, "title": "from dpo" }
than 17 ft, widen to 17 ft or use Figure 910-10b. (4) See Standard Plans and MUTCD for pavement marking details. Median Channelization (Minimum Protected Storage) Figure 910-10e Design Manual M 22-01 Intersections At Grade January 2005 Page 910-37 U-Turn Locations > Figure 910-16 ChapterF9104.doc WSDOT Design Manual In...	{ "page_id": null, "source": 7320, "title": "from dpo" }
shoulder pavement designed to the same depth as the through lanes for the acceleration length and taper. Intersections At Grade Design Manual M 22-01 Page 910-38 May 2006 Design Manual for Design-Build Projects Intersections At Grade November 2004 Page 910-41 SiLine of Sight SiLine of Sight VVgi 1.47Vt S Where: Si = In...	{ "page_id": null, "source": 7320, "title": "from dpo" }
V = Design speed of the through roadway (mph) tg = Time gap for the minor roadway traffic to enter or cross the through roadway (sec) Intersection Sight Distance Equation Table 1 Design Vehicle Time Gap (t g )in sec Passenger car (P) 9.5 Single unit trucks and buses (SU & BUS) 11.5 Combination trucks (WB-40, WB-50, & W...	{ "page_id": null, "source": 7320, "title": "from dpo" }
1,000 feet to accommodate future ramp improvements. This distance may be decreased to improve winter maintenance efficiency based on an operational analysis. Include an operational analysis in the Design Documentation Package. ## 960.03 Design Utilize the following design criteria for all median crossovers, while takin...	{ "page_id": null, "source": 7320, "title": "from dpo" }

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