Highway Safety Manual Knowledge Base - Cmfclearinghouse
Highway Safety Manual Knowledge Base This is an updated version of a document that was originally prepared by the NCHRP 17-27 project team that included the following individuals: Geni Bahar, P. Eng., iTRANS Consulting Ltd. Margaret Parkhill, P. Eng., iTRANS Consulting Ltd. Errol Tan, P. Eng., iTRANS Consulting Ltd. Chris Philp, P. Eng., iTRANS Consulting Ltd. Nesta Morris, M.Sc. (Econ), iTRANS Consulting Ltd. Sasha Naylor, EIT, iTRANS Consulting Ltd. Tammi White, iTRANS Consulting Ltd. in association with Dr. Ezra Hauer, University of Toronto Dr. Forrest M. Council, Bellomo-McGee Inc. Dr. Bhagwant Persaud, Ryerson University Charles Zegeer, UNC Highway Safety Research Center Dr. Rune Elvik, Institute of Transport Economics Dr. Alison Smiley, Human Factors North Inc. Betty Scott, Betty Scott & Associates The original document prepared by the NCHRP 17-27 project team included a review of studies that were published until December 2004. This updated version includes accident modification factors (AMFs) based on a review of studies from January 2005 until April 2008. The update was done by the following individuals based on funding from the Federal Highway Administration: Dr. Raghavan Srinivasan, UNC Highway Safety Research Center Dr. Darren Torbic, Midwest Research Institute Dr. Forrest Council, UNC Highway Safety Research Center David Harkey, UNC Highway Safety Research Center November 2009
Preface The Knowledge Base forms the foundation for the contents of each chapter of Part D of the First Edition of the Highway Safety Manual (HSM). It is expected that this Knowledge Base, which documents the extensive literature review completed, will be of interest to highway safety professionals, and will be of use for the development of future editions of the HSM. The following chapters are included in this document: Chapter 3: Roadway Segments Chapter 4: Intersections Chapter 5: Interchanges Chapter 6: Special Facilities and Geometric Situations Chapter 7: Road Networks In this document, safety effects are presented as Accident Modification Factors or Functions (AMFs). AMFs are typically estimated for three accident severities: fatal, injury, and non-injury. Fatal and injury are generally combined and noted as injury. Where distinct AMFs are available for fatal and injury severities, they are presented separately. Non-injury severity is also known as property-damageonly severity. Each AMF is accompanied by a measure of accuracy, the standard error. A small standard error indicates that an AMF is accurate. The development of the Knowledge Base of the Highway Safety Manual (HSM) required a formalized process and procedure to review, document, and filter the multitude of safety information published in the last 50 years until April 2008. The procedures that were applied in the development of the Knowledge Base including the method correction factors (MCFs) are provided in a companion document: “Inclusion Process and Literature Review Procedure for Part D”
Chapter 3: Roadway Segments
Chapter 3. Roadway Segments CONTENTS 3.1. 3.2. 3.3. Safety Effects of Roadway Segment Design Elements . 3-10 3.1.1. Roadway Elements . 3-10 3.1.1.1. Lanes . 3-10 3.1.1.2. Shoulders . 3-26 3.1.1.3. Medians . 3-37 3.1.2. Roadside Elements . 3-48 3.1.2.1. Roadside Geometry . 3-49 3.1.2.2. Roadside Features . 3-61 3.1.2.3. Roadside Barriers. 3-69 3.1.2.4. Roadside Safety Analysis Program . 3-78 3.1.2.5. Roadside Hazard Rating. 3-80 3.1.3. Alignment Elements . 3-85 3.1.3.1. Horizontal Alignment . 3-85 3.1.3.2. Vertical Alignment. 3-93 3.1.3.3. Combination Horizontal and Vertical Alignment [Future Edition]3-98 Safety Effects of Roadway Segment Traffic Control and Operational Elements. 3-99 3.2.1. Signs. 3-99 3.2.2. Delineation . 3-108 3.2.3. Rumble Strips . 3-126 3.2.3.1. Shoulder Rumble Strips . 3-127 3.2.3.2. Centerline Rumble Strips. 3-134 3.2.3.3. Transverse Rumble Strips. 3-137 3.2.3.4. Mid-lane Rumble Strips [Future Edition] . 3-141 3.2.3.5. Edgeline Rumble Strips [Future Edition]. 3-141 3.2.4. Passing Zones on Two-Lane Roads . 3-142 3.2.5. Speed Limits [Future Edition]. 3-143 3.2.6. Traffic Calming . 3-144 3.2.7. Speed Zoning . 3-154 3.2.8. On-Street Parking . 3-157 3.2.9. Intelligent Transportation Systems and Traffic Management Systems [Future Edition]. 3-169 Pedestrian and Bicyclist Safety on Roadway Segments . 3-169 3.3.1. Sidewalks and Shoulders . 3-170 3.3.2. Mid-block Crossing Design and Traffic Control. 3-174 3-1
3.4. 3.3.3. Pedestrian Refuges . 3-187 3.3.4. Bicycle Routes. 3-193 3.3.5. School Routes and School Zones [Future Edition]. 3-205 3.3.6. Weather Issues [Future Edition]. 3-206 Safety Effects of Other Roadway Segment Elements. 3-206 3.4.1. Highway Illumination . 3-206 3.4.2. Increase Pavement Friction. 3-211 3.4.3. Access Points. 3-213 3.4.4. Transit Stop Placement [Future Edition]. 3-221 3.4.5. Weather Issues. 3-221 3.4.5.1. Adverse Weather and Low Visibility Warning Systems. 3-221 3.4.5.2. Snow, Slush, and Ice Control . 3-224 3.4.5.3. Wet Pavement [Future Edition] . 3-232 3.4.6. Pavement Materials [Future Edition]. 3-233 3.4.7. Animals [Future Edition]. 3-234 EXHIBITS Exhibit 3-1: Resources examined to investigate the safety effect of lane attributes on road segments . 3-11 Exhibit 3-2: Individual and combined AMFs for lane width for all crash types on two-lane rural roads as reviewed by (Hauer, 2000) (2). 3-18 Exhibit 3-3: AMFs for lane width for selected crash types on two-lane rural roads (7) . 3-19 Exhibit 3-4: AMFs for lane width on two-lane rural roads with AADT of 2,000 veh/day or more (7). 3-19 Exhibit 3-5: AMFs for lane width for four-lane roads (5). 3-21 Exhibit 3-6: Safety Effects of Lane Width for Rural Frontage Roads (169) . 3-22 Exhibit 3-7: AMFs for providing an additional lane on urban freeways by narrowing 12 ft lanes to 11 ft or wider and narrowing the inside shoulder (4). 3-23 Exhibit 3-8: AMFs for “Road Diets” (168) . 3-25 Exhibit 3-9: Resources examined to investigate the safety effect of shoulder attributes on roadway segments . 3-27 Exhibit 3-10: Summary of study characteristics for shoulder width on two-lane rural roads . 3-30 Exhibit 3-11: AMFs for shoulder width for related accidents on two-lane rural roads (7) . 3-31 Exhibit 3-12: AMFs for total crashes on two-lane rural roads with ADT of 2,500 veh/day or greater (7). 3-32 Exhibit 3-13: Summary of AMFs for paved shoulder widening on total crashes on two-lane rural roads with any volume . 3-32 3-2
Exhibit 3-14: Summary of study characteristics for shoulder width on multi-lane roads (9) . 3-33 Exhibit 3-15: AMFs for total crashes on urban or rural multi-lane roads with ADT of 2,500 veh/day or greater (5). 3-33 Exhibit 3-16: AMFs for crashes on urban or rural multi-lane roads (3). 3-34 Exhibit 3-17: Safety Effects of Paved Shoulder Width on Rural Frontage Roads (169). 3-35 Exhibit 3-18: Summary of study characteristics for shoulder type (7,9). 3-36 Exhibit 3-19: Accident Modification Factors for Shoulder Types on Two-Lane Highways for single-vehicle run-off-the-road and opposite-direction accidents (7). 3-36 Exhibit 3-20: AMFs for total crashes for conversion to/from different shoulder types on two-lane rural roads . 3-37 Exhibit 3-21: Resources examined to investigate the safety effect of medians on roadway segments . 3-38 Exhibit 3-22: Summary of study characteristics for median presence on two-lane roads. 3-42 Exhibit 3-23: Summary of study characteristics for median presence . 3-43 Exhibit 3-24: Summary of study characteristics for median width . 3-45 Exhibit 3-25: Summary of findings concerning AMFs for increasing median width . 3-46 Exhibit 3-26: AMFs for changing median widths on full access control roadways (168) . 3-47 Exhibit 3-27: AMFs for changing median widths on partial or no access control roadways (168)3-47 Exhibit 3-28: Roadside geometry (25) . 3-50 Exhibit 3-29: Resources examined to investigate the safety effect of roadside geometry on segments . 3-51 Exhibit 3-30: Percent reductions in “related accidents” due to increasing the roadside clear recovery distance on two-lane rural roads (Zegeer et al., 1988 as cited in (16)) . 3-54 Exhibit 3-31: Relationship between single-vehicle accident rate (run-off-road; per mile per year) and ADT for two-lane highways with various clear zone policies (28) . 3-55 Exhibit 3-32: Safety effectiveness of flattening sideslopes from 1V:3H to 1V:4H (8) (20) . 3-56 Exhibit 3-33: Safety effectiveness of flattening sideslopes from 1V:4H to 1V:6H (8) (20) . 3-57 Exhibit 3-34: Relationship between single-vehicle accident rate and sideslope, relative to accident rate for a sideslope of 7:1 [1V:7H] or flatter (Zegeer et al., 1987 as cited by (28)) . 3-57 Exhibit 3-35: Percentage reduction of single-vehicle and total crashes due to sideslope flattening on two-lane rural roads (Zegeer et al., 1987 as cited by (16)). . 3-58 Exhibit 3-36: Safety effectiveness of raised curbs on urban four-lane undivided roads (3) . 3-59 Exhibit 3-37: Safety Effectiveness of raised curbs on high-speed suburban multi-lane highways (non-freeways) (29) . 3-60 Exhibit 3-38: Resources examined to investigate the safety effect of roadside features on segments . 3-61 Exhibit 3-39: Safety effects of increased distance to roadside features (8). 3-65 Exhibit 3-40: AMFs for specific types of obstacle accidents due to clearing/relocating obstacles farther from the roadway on two-lane rural roads (Zegeer et al., 1990 as cited in (16)) . 3-66 Exhibit 3-41: AMFs for utility poles accidents for moving poles farther from the roadway (Zegeer and Cynecki, 1984 as cited in (30)) . 3-67 3-3
Exhibit 3-42: Roadside adjustment factors for placing utility lines underground, increasing lateral offsets, and multiple pole use; for use in conjunction with Exhibit 3-41 (33). 3-68 Exhibit 3-43: Resources examined to investigate the safety effect of roadside barriers on roadway segments . 3-70 Exhibit 3-44: Safety effect of guardrails along the roadside (8) . 3-73 Exhibit 3-45: Safety effect of guardrails and guardrail type in the median of multi-lane divided highways (8) . 3-74 Exhibit 3-46: Safety effect of placing beam barrier in 4 ft median on expressway with ADT 130,000 veh/day (15) . 3-75 Exhibit 3-47: Safety effect of wire guardrails between opposing lanes of traffic on three-lane undivided roads (8) . 3-76 Exhibit 3-48: Safety effect of new crash cushions at permanent objects (8). 3-77 Exhibit 3-49: Resources examined for the Roadside Safety Analysis Program. 3-78 Exhibit 3-50: Resources examined for the Roadside Hazard Rating . 3-80 Exhibit 3-51: Quantitative descriptors for the seven Roadside Hazard Ratings (7). 3-81 Exhibit 3-52: Typical roadway with Roadside Hazard Rating of 1. 3-82 Exhibit 3-53: Typical roadway with Roadside Hazard Rating of 2. 3-82 Exhibit 3-54: Typical roadway with Roadside Hazard Rating of 3. 3-83 Exhibit 3-55: Typical roadway with Roadside Hazard Rating of 4. 3-83 Exhibit 3-56: Typical roadway with Roadside Hazard Rating of 5. 3-84 Exhibit 3-57: Typical roadway with Roadside Hazard Rating of 6. 3-84 Exhibit 3-58: Typical roadway with Roadside Hazard Rating of 7. 3-85 Exhibit 3-59: Resources examined to investigate the safety effect of horizontal alignment on road segments . 3-86 Exhibit 3-60: AMFs for off-the-road accidents for one degree increase in horizontal curvature on urban and suburban arterials (3) . 3-89 Exhibit 3-61: AMFs for superelevation deficiency (SD) of horizontal curves on two-lane rural roads (7) . 3-90 Exhibit 3-62: AMFs for superelevation deficiency (SD) of horizontal curves on two-lane rural roads (7) . 3-90 Exhibit 3-63: AMFs for short tangents (T) followed by a sharp curve (R radius) (42) . 3-91 Exhibit 3-64: Resources examined to investigate the safety effect of vertical grade on roadway segments . 3-94 Exhibit 3-65: List of studies reviewed by Hauer (Table 7.18 from (46)). 3-96 Exhibit 3-66: Accident Modification Factors for all accidents for Increased Grade of Two-Lane Rural Roadway Sections (7) . 3-97 Exhibit 3-67: Potential resources for the relationship between combined horizontal and vertical alignment and safety . 3-99 Exhibit 3-68: Resources examined to investigate the safety effect of Signs on Roadway Segments3-100 Exhibit 3-69: Safety effectiveness of installing signs to conform to MUTCD (8). 3-102 Exhibit 3-70: Safety effectiveness of active close-following warning signs on road segments (8)3-103 3-4
Exhibit 3-71: Safety effectiveness of limited sight distance signs on road segments(as cited in (51)) . 3-103 Exhibit 3-72: Safety effectiveness of changeable curve speed warning signs on horizontal curves3-104 Exhibit 3-73: Safety effectiveness of horizontal alignment signs . 3-105 Exhibit 3-74: Safety effectiveness of combination horizontal alignment/ advisory speed signs (W1-1a, W1-2a) . 3-106 Exhibit 3-75: Safety effectiveness of dynamic/variable accident warning signs on roadway segments (8). 3-107 Exhibit 3-76: Safety effectiveness of changeable queue warning signs on roadway segments (8)3-107 Exhibit 3-77: Safety effectiveness of changeable speed warning signs on road segments (8). 3-108 Exhibit 3-78: Resources examined to investigate the safety effect of delineation on road segments3-109 Exhibit 3-79: Safety effectiveness of post-mounted delineators on roadway segments (8). 3-113 Exhibit 3-80: Safety effectiveness of chevron signs on horizontal curves (62) . 3-116 Exhibit 3-81: Safety effectiveness of placing standard edgeline markings (8) . 3-117 Exhibit 3-82: Safety effectiveness of placing wide edgeline markings (8) . 3-117 Exhibit 3-83: Safety effectiveness of placing centerline markings (8). 3-118 Exhibit 3-84: Safety effectiveness of installing lane lines on multilane roadway segments (8)3-119 Exhibit 3-85: Safety effectiveness of installing distance markers (angle symbols) on roadway segments (8). 3-119 Exhibit 3-86: Safety effectiveness of edgelines and background/directional markings on horizontal curves (8) . 3-120 Exhibit 3-87: Safety effectiveness of combination of raised pavement markers and transverse rumble strips on approach to horizontal curves . 3-121 Exhibit 3-88: Safety effectiveness of edgelines and centerlines on roadway segments. 3-123 Exhibit 3-89: Safety effectiveness of edgelines, centerlines and post-mounted delineators . 3-123 Exhibit 3-90: Safety effectiveness of snowplowable permanent RPMs on two-lane roadway segments (57). 3-124 Exhibit 3-91: Safety Effectiveness of Snowplowable PRPMs on Four-Lane Freeways. 3-125 Exhibit 3-92: Safety effectiveness of converging chevron pattern markings on roadway segments3-126 Exhibit 3-93: Resources examined to investigate the safety effect of shoulder rumble strips . 3-129 Exhibit 3-94: Safety effectiveness of shoulder rumble strips on rural multi-lane highways, including freeways. 3-132 Exhibit 3-95: Safety effectiveness of shoulder rumble strips in conjunction with shoulder widening on freeways (74) . 3-133 Exhibit 3-96: Resources examined to investigate the safety effect of centerline rumble strips on undivided roadways . 3-134 Exhibit 3-97: Safety effectiveness of centerline rumble strips on rural two-lane roads (75) . 3-136 Exhibit 3-98: Resources examined to investigate the safety effect of transverse rumble strips on segments . 3-138 Exhibit 3-99: Safety effectiveness of transverse rumble strips and raised pavement markers on approach to horizontal curves on rural two-lane roads . 3-140 3-5
Exhibit 3-100: Potential resources on the relationship between mid-lane rumble strips and safety3-141 Exhibit 3-101: Potential resources on the relationship between edgeline rumble strips and safety3-141 Exhibit 3-102: Resources examined to investigate the relationship between passing zones and safety. 3-143 Exhibit 3-103: Potential resources on the relationship between speed limits and safety . 3-144 Exhibit 3-104: Resources examined on the safety effect of traffic calming. 3-145 Exhibit 3-105: Studies included in synthesis of evidence of safety effects of traffic calming (8)3-147 Exhibit 3-106: Studies that have evaluated effects of speed humps, raised pedestrian crosswalks and transverse rumble strips (8). 3-147 Exhibit 3-107: Summary estimates of the effect on accidents of traffic calming (8). 3-149 Exhibit 3-108: Relationship between effect on speed and effect on injury accidents of traffic calming (8). 3-150 Exhibit 3-109: Effects on injury accidents of speed humps (8). 3-151 Exhibit 3-110: Effects on injury accidents of raised pedestrian crosswalks (8). 3-152 Exhibit 3-111: Effects on accidents of transverse rumble strips (8). 3-153 Exhibit 3-112: Resources examined to investigate the safety effect of speed zoning on roadway segments . 3-154 Exhibit 3-113: Effects on accidents of changes in the mean speed of traffic (84) . 3-156 Exhibit 3-114: Relationship between changes in speed limits (km/h) and change in the mean speed of traffic (km/h). Based on studies reviewed by Elvik et al. (84) . 3-157 Exhibit 3-115: Resources examined to investigate the safety effect of on-street parking on roadway segments. 3-158 Exhibit 3-116: Safety effectiveness of prohibiting on-street parking on urban roadway segments3-161 Exhibit 3-117: Safety effectiveness of prohibiting on-street parking on urban roadway segments to off-the-road areas. 3-163 Exhibit 3-118: Safety effectiveness of prohibit on-street parking on one side of urban roadway segments . 3-163 Exhibit 3-119: Safety effectiveness of converting free to regulated on-street parkings (8) . 3-164 Exhibit 3-120: Safety effectiveness of implementing time-limited on-street parking (8). 3-165 Exhibit 3-121: Safety effectiveness of converting angle parking to parallel parking on urban roadway segments. 3-166 Exhibit 3-122: Safety effectiveness of converting parallel parking to angle parking on urban roadway segments. 3-168 Exhibit 3-123: Safety effectiveness of marking parking spaces on urban roadway segments . 3-168 Exhibit 3-124: Potential resources on the relationship between intelligent transportation systems and safety . 3-169 Exhibit 3-125: Resources examined to investigate the relationship between the provision of sidewalks or shoulders and safety. 3-171 Exhibit 3-126: Model results for three variables (Table 4 of (102)) . 3-173 Exhibit 3-127: Potential resources on the relationship between the mid-block pedestrian crossings and safety . 3-175 3-6
Exhibit 3-128: Effects on injury accidents of raised pedestrian crosswalks (8). 3-181 Exhibit 3-129: Comparison of crashes before and after installation of pedestrian overpasses (Tokyo, Japan) (83). 3-184 Exhibit 3-130: Resources examined for the relationship between pedestrian refuge islands (medians) and safety . 3-187 Exhibit 3-131: Safety effectiveness of raised medians on pedestrian crashes on segments. 3-190 Exhibit 3-132: Safety Performance of Pedestrian Devices in Toronto (123). 3-191 Exhibit 3-133: Types of Crashes at Pedestrian Refuge Islands and Split Pedestrian Crossovers (123). 3-191 Exhibit 3-134: Resources examined to investigate the safety effect of bicycle facilities on roadway segments. 3-194 Exhibit 3-135: Potential resources on safety of school routes and school zones . 3-205 Exhibit 3-136: Potential resources on weather issues and pedestrian and bicycle safety on segments .
Highway Safety Manual Knowledge Base This is an updated version of a document that was originally prepared by the NCHRP 17-27 project team that included the following individuals: Geni Bahar, P. Eng., iTRANS Consulting Ltd. Margaret Parkhill, P. Eng., iTRANS Consulting Ltd. Errol Tan, P. Eng., iTRANS Consulting Ltd.
download the sample spreadsheets and color PDF file of this guide. 16. Abstract The Highway Safety Manual User Guide is a user friendly document that helps safety analysts begin to use the Highway Safety Manual (HSM). The Highway Safety Manual User Guide is a companion document to the HSM and is used as a reference document. It is not a
1.2 Highway Safety Manual . The Highway Safety Manual (HSM) is a resource that provides safety knowledge and tools in a useful f orm to facilitate improved decision making based on safety performance. The HSM is an AASHTO manual that includes methodologies to quantitatively predict a facility's safety performance. The "Predictive Method"
The Highway Safety Manual (HSM) is the national manual on highway safety just as the Highway Capacity Manual, the AASHTO Green Book, and the Manual of Uniform Traffic Control Devices are national manuals on capacity/level-of-service, geometric design, and traffic control devices. With the advent of the HSM, transportation engineers now have a .
that would serve the field of highway safety in the same way that the Highway Capacity Manual had served the field of operations. This group became the core of a larger team that has focused substantial amounts of professional and volunteer time on this vision. The vision became reality 11 years later, with the publication of the Highway Safety .
Highway Safety Program Manual: Volume 8: Alcohol in Relation to Highway Safety. National Highway Traffic Safety Administration (DOT), Washington, D. C. Mar 75 66p.; For related documents, see CE 003 883-901 Superintendent of Documents, U. S. Government Printing Office, Washington, D. C. 20402 (No price given) EDRS PRICE MF- 0.76 HC- 3.32 PLUS .
implement their Strategic Highway Safety Plans (SHSP). A new generation of safety analysis tools and methods has been developed to help identify safety issues and provide recommendations for improvements. These safety analysis tools, such as the Highway Safety Manual (HSM), SafetyAnalyst, and the Interactive Highway Safety Design
NJDOT operations dictate that Interstate, US Highway and State Highway designations are considered higher order routes than Highway Authority Routes. The full hierarchy follows in descending order: 1 – Interstate 2 – US Highway 3 – State Highway 4 – Highway Authority Route 5 – 500
Adopt-A-Highway Program Guidelines and Coordinators Handbook Adopt-A-Highway Signs March 2008 2-3 PURPOSE OF SIGNS Caltrans recognizes donations made through the Adopt-A-Highway Program with Adopt-A-Highway courtesy signs. Courtesy signs also alert motorists and the California Highway Patrol that workers may be present on the roadside.File Size: 964KB
