Statistical Analysis Resources
A Policy on Geometric Design of Highways and Streets, 5th Edition, AASHTO Green Book.
This fifth edition of AASHTO's "Green Book" contains the latest design practices in universal use as the standard for highway geometric design and has been updated to reflect the latest research on superelevation and side friction factors as presented in NCHRP Report 439.
AASHTO Strategic Highway Safety Plan [PDF 1.20 MB]
The AASHTO Strategic Highway Safety Plan contains 22 emphasis areas. This plan is built on existing safety programs, such as the National Safety Council’s (NSC’s) National Agenda for Safety Records, the Strategic Plan for Improving Roadside Safety—a program developed through the National Cooperative Highway Research Program (NCHRP) and the Emergency Medical Services (EMS) Strategic Plan.
Access Management in the Vicinity of Intersections: Technical Summary | Presentation
This technical summary is designed as a reference for State and local transportation officials, Federal Highway Administration (FHWA) Division Safety Engineers, and other professionals involved in the design, selection, and implementation of access management near traditional intersections (e.g., signalized, unsignalized and stop-controlled intersections).
Access Management Manual, ISBN: 0-309-07747-8, Transportation Research Board, The National Academies, 2003.
This TRB Manual provides technical information on access management techniques, together with information on how to develop and administer effective access management programs. It presents access management—the systematic control of the location, spacing, design, and operation of driveways, median openings, interchanges, and street connections to a roadway—comprehensively, in an effort to integrate planning and engineering practices with the transportation and land use decisions that contribute to access outcomes.
- To order the Access Management Manual, contact the TRB Business Office at 202-334-3213 or TRBSales@nas.edu
Appendix A: Summary of Intersection Safety Studies
Appendix to Safety Effectiveness of Intersection Left and Right Turn Lanes. D.W. Harwood, et. al., FHWA-RD-02-089, July 2002.
- Complete Report [PDF 1.49 MB]
Crash Reduction Factors Desktop Reference [PDF 834 KB]
Driver Attitudes and Behaviors at Intersections and Potential Effectiveness of Engineering Countermeasures, FHWA-HRT-05-158, March 2006. [HTML, PDF 289KB]
Research was conducted to provide FHWA with information about key attitudes and behavioral influences in intersection driving performance, perceptual and cognitive bottlenecks, and constraints that can have a negative impact on intersection safety. The research also addresses engineering or educational countermeasures for intersection safety that have the greatest likely impact on performance and safety. This research includes a task analysis of driver performance at intersections, a literature review on human factors research as it relates to highway infrastructure and focus group discussions that explore driver attitudes and behaviors at intersections.
FHWA's Intersection Resources Library CD-ROM, FHWA-SA-09-27
Resources included in this library represent a broad cross section of publications, educational materials and other media published by the Federal Highway Administration and other transportation safety partners.
FHWA Report Summaries
- Roundabouts: An Informational Guide (2000) [DOC 44 KB]
- Signalized Intersections: Informational Guide (2004) [DOC 44 KB]
- Innovative Intersection Safety Improvement Strategies and Management Practices - A Domestic Scan (2006) [DOC 47 KB]
- Making Intersections Safer: A Toolbox of Engineering Countermeasures to Reduce Red-Light Running, An Informational Report (2003) [DOC 46 KB]
- Field Guide for Inspecting Signalized Intersections to Reduce Red-Light Running (2005) [DOC 46 KB]
- Red Light Camera Systems Operational Guidelines (2005) [DOC 44 KB]
- Safety Evaluation of Red-Light Cameras (2005) [DOC 44 KB]
- Toolbox on Intersection Safety and Design (2004) [DOC 44 KB]
- Railroad-Highway Grade Crossing Handbook (2007) [DOC 44 KB]
Florida Intersection Design Guide for New Construction and Major Reconstruction of At-Grade Intersections on the State Highway System [PDF 3.58 MB]
The chapters within this document contain the following: (1) Introduction; (2) Intersection Design Concepts; (3) Geometric Design; (4) Signalization; (5) Signs and Markings; and (6) Objects and Amenities.
Innovative Intersection Safety Improvement Strategies and Management Practices; A Domestic Scan, FHWA-SA-06-016, September 2006.
A primary objective was to identify and document selected innovative intersection treatments implemented at intersections in the United States and that demonstrate, or have the potential to improve safety at intersections. Another objective was to identify and document selected comprehensive safety processes and procedures that have been implemented by transportation agencies specifically to improve transportation safety. The five locations visited during this scan were: Southeastern, Michigan; North Central, Texas; North Central, Oregon; Charlotte, NC; and West Palm Beach, FL. This report provides a discussion on the successes and challenges to enhancing safety for highway users.
Interactive Highway Safety Design Model (IHSDM)
IHSDM is a suite of software analysis tools for evaluating safety and operational effects of geometric design decisions on two-lane rural highways. IHSDM is a decision-support tool. It checks existing or proposed two-lane rural highway designs against relevant design policy values and provides estimates of a design’s expected safety and operational performance. IHSDM results support decision making in the highway design process. IHSDM currently includes five evaluation modules (Crash Prediction, Design consistency, Intersection Review, Policy Review, and Traffic Analysis). A sixth module (Driver/Vehicle) is under development. The linked Website also provides a library of the research reports documenting their development.
Intersection Safety Case Studies
Intersection Safety Implementation
Intersection Safety Individual Guide Sheets
This key sheet and the accompanying intersection safety strategy guide sheets are companions to the NCHRP Report 500 series on strategies to reduce crashes at unsignalized (Volume 5) and signalized (Volume 12) intersections.
Intersection Safety Issue Briefs, Third Edition
This resource is a series of Issue Briefs on various intersection safety-related topics. Many products have developed over the past 5 years to help practitioners evaluate causes of intersection crashes and potential solutions. The issue briefs provide practitioners with a substantial number of references and resources for subsequent review and consideration. The topics that are included within this intersection safety communications kit include:
- The National Intersection Safety Problem
- Traffic Control Devices: Uses and Misuses
- Stop Signs
- Engineering Countermeasures to Reduce Red-Light Running
- Red-Light Cameras
- Intersection Safety Countermeasures
- Pedestrian Safety
- Older Road Users
- ADA Considerations at Intersections
- Human Factors
- Access Management
- Road Safety Audits
- Work Zones
Intersection Safety Needs Identification Report
This report identifies needs in developing and achieving safety performance through enhanced activities that can reduce crashes and their impacts—specifically the fatalities and serious injuries associated with intersection safety within their jurisdictions.
Intersection Safety Strategies Brochure
Intersection Safety Technologies
Stop-Controlled Intersection Safety: Through Route Activated Warning System, FHWA-SA-11-023, May 2011
An infrastructure-based Intelligent Transportation System (ITS) used to help reduce the potential for and severity of crashes.
Advanced Dilemma-Zone Detection System, FHWA-SA-09-008, May 2009
This system enhances safety at signalized intersections by modifying traffic control signal timing to reduce the number of drivers that may have difficulty deciding whether to stop or proceed during a yellow phase.
Embedded LEDs in Signs, FHWA-SA-09-006, May 2009
LEDs in sign faces that improve safety at intersections by enhancing driver awareness of traffic-control signs.
LED Raised Pavement Markers, FHWA-SA-09-007, May 2009
These pavement markers improve the safety of intersection approaches, as well as pedestrian, bicycle and other crossings. These markers enhance delineation and driver awareness, especially in low visibility conditions.
Rectangular Rapid Flash Beacon (RRFB), FHWA-SA-09-009, May 2009
RRFB can enhance safety by reducing crashes between vehicles and pedestrians at unsignalized intersections and mid-block pedestrian crossings by increasing driver awareness of potential pedestrian conflicts.
Red-Signal Enforcement Lights, FHWA-SA-09-005, May 2009
Lights that enhance safety at signalized intersections by improving red-light compliance, resulting in a reduction of red-light running violations.
Key Intersection Safety Resources
Low-Cost Safety Enhancements for Stop-Controlled and Signalized Intersections
The purpose of this document is to present information on suggested effective, low-cost intersection countermeasures developed using intersection safety research results and input from an intersection safety expert panel.
Manual on Uniform Traffic Control Devices
National Agenda for Intersection Safety
The National Agenda for Intersection safety was developed as a result of the information, data and discussions that occurred at the National Intersection Safety Workshop held in Milwaukee, WI on November 14-16, 2001. The National Agenda for Intersection Safety should be viewed as a “living document”, and as such, will be modified periodically based on comments received and actions implemented by transportation and safety agencies.
NCHRP Report 457: Evaluating Intersection Improvements: An Engineering Study Guide, 2001. [PDF 3.33 MB]
This is a guide to the engineering study of intersections having operational problems. It describes a process for evaluating the operational effectiveness of various intersection improvements and also shows how capacity analysis and traffic simulation models can be used to assess the operational impacts of those improvements. Junior traffic engineers, especially, will find the guide enhances the decision-making process and can reduce inappropriate traffic control signal installations. The Texas Transportation Institute developed the report for NCHRP.
NCHRP Report 486: Systemwide Impact of Safety and Traffic Operations Design Decisions for 3R Projects [PDF 3.85 MB]
Existing knowledge of the safety and traffic-operational effects of geometric improvements has not previously been sufficiently organized and evaluated to assist highway agencies in assessing the trade-offs between these competing goals. TRB Special Report 214 and the design policies of several states provide general guidelines for improving intersections in 3R projects. In particular, TRB Special Report 214 recommends that State highway agencies develop consistent procedures and checklists for evaluating intersection improvements on 3R projects.
NHI Course FHWA-NHI-380074 Designing and Operating Intersections for Safety
Through numerous interactive discussions, exercises, and case studies, this course examines various aspects of design and operations and how they affect the safety of an intersection and its various users. The full course contains a total of six modules: Users and Intersections, Diagnostics and Countermeasures, Geometric Design, Unsignalized Intersections, Signalized Intersections, and Case Studies.
NEW Proven Safety Countermeasures
Several intersection safety related treatments are featured among the nine Proven Safety Countermeasures that are the subject of the 2012 Guidance Memorandum on Promoting the Implementation of Proven Safety Countermeasures.
Report on the National Agenda for Intersection Safety
The agenda lists strategies and implementation follow-on activities that need to be assessed to determine uses, relevance and implementation of the Agenda, and potential future updating, as well as, implementation approaches and activities.
Safety Analyst is envisioned as a set of software tools used by state and local highway agencies to improve their programming of site-specific highway safety improvements. Safety Analyst will incorporate state-of-the-art safety management approaches into computerized analytical tools for guiding the decision-making process to identify safety improvement needs and develop a system wide program of site-specific improvement projects. Safety Analyst will have a strong basis in cost-effectiveness analysis.
Safety Effectiveness of Intersection Left- and Right-Turn Lanes, FHWA-RD-02-089, July 2002. [HTML, PDF 1.48 MB]
Report presents results of research that performed a well-designed before-after evaluation of the safety effects of providing left- and right-turn lanes for at-grade intersections. Geometric design, traffic control, traffic volume, and traffic accident data were gathered for a total of 280 improved intersections, as well as 300 similar intersections that were not improved during the study period. The types of improvement projects evaluated included installation of added left-turn lanes, added right-turn lanes, and extension of the length of existing left- or right-turn lanes. An observational before-after evaluation of these projects was performed using several alternative evaluation approaches. The three contrasting approaches to before-after evaluation used were the yoked comparison or matched-pair approach, the comparison group approach, and the empirical Bayes approach. The research not only evaluated the safety effectiveness of left- and right-turn lane improvements, but also compared the performance of these three alternative approaches in making such evaluations. The research developed quantitative safety effectiveness measures for installation design improvements involving added left-turn lanes and added right-turn lanes. The research concluded that the empirical Bayes method provided the most accurate and reliable results.
Stop-Controlled Intersection Safety: Through Route Activated Warning Systems
This report provides information on low cost infrastructure based ITS technologies that may be applied to stop-controlled intersections to improve safety.
Strategic Intersection Safety Program Guide
This guide serves as a tool to assist agencies at the State and local levels in developing strategic, systematic approaches for planning, developing, implementing, and maintaining an intersection safety program.
TechBrief: Safety Effectiveness of Intersection Left- and Right-Turn Lanes. [HTML, PDF 668 KB]
This report presents the results of research on the safety effectiveness of providing left- and right-turn lanes for at-grade intersections.
Toolbox on Intersection Safety and Design
This informational report (1) demonstrates practical design measures and tools that will improve intersection safety, balanced with intersection operational capacity, (2) provides examples of effective applications, and (3) discusses experiences with innovative solutions. Many of these measures, tools, applications and innovative solutions were presented and discussed during the ITE 2004 Technical Conference and Exhibit, “Intersection Safety: Achieving Solutions Through Partnerships.” ITE 2004. ISBN No: 0-935403-91-4.
Traffic Control Devices Handbook
The Traffic Control Devices Handbook provides guidance and information to implement the provisions of the MUTCD. The objective of the Handbook is to bridge the gap between the MUTCD requirements and field applications. Additional guidance is provided on the new MUTCD requirements to clarify these Manual provisions. ITE, 2001, 521 pp., ISBN No: 0-935403-66-3
Traffic Safety Toolbox: A Primer on Traffic Safety
The following topics are covered: Safety Management; Traffic Planning; Traffic Control Devices; Tort Liability, Risk Management and Sign Inventory Systems; Geometric Design; One-Way Streets and Reversible Lanes; Roadside Safety; Enforcement; Automated Enforcement of Red Light Running; Infrastructure Maintenance: Traffic Control Devices; Work Zone Traffic Management; Designing for Pedestrians; Bicycling Element; Driver Behavior and Qualification; Traffic Calming; Teaching Safety; Before-After Evaluations in Highway Safety; Statistical Approach to the Analysis of Intersection Safety; Safety Improvements and Secondary Roadways; Low-Cost Safety Improvements; Safety Impacts of Roundabouts; Road Safety Audit. ITE, 1999. ISBN 0-935403-43-4.
Validation of Accident Models for Intersections, May 2005, FHWA-RD-03-037. [HTML, PDF 1.61 MB]
This report describes the results of validation and calibration of motor vehicle crash models for rural intersections. Both the validation and recalibration activities were conducted in pursuit of one overriding research objective, which was to make marginal improvements to an existing set of statistical models for predicting crashes at two and four lane intersections, with the primary intent to be used in the Interactive Highway Safety Design Module (IHSDM).
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Statistical Analysis Resources
Intersection Decision Support Project Seeks to Prevent Broadside Crashes. [HTML, PDF 271 KB].
Method for Prioritizing Intersection Improvements, Washington State Transportation Center (TRAC), January 1997. [PDF 163 KB].
Statistical Model of At-Grade Intersection Accidents-Addendum, FHWA-RD-99-094, March 2000. [PDF 343 KB].
Validation of Accident Models for Intersections, May 2005, FHWA-RD-03-037. [HTML, PDF 1.61MB].
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State DOT Reports
Safety Evaluation of Left-Turn Lane Width at Intersections with Opposing Left-Turn Lanes, University of Nebraska, SPR-PI(03) P554, December 2004. [PDF 2.53 MB]
Update of Florida Crash Reduction Factors and Countermeasures to Improve the Development of District Safety Improvement Projects. Final Report, State of Florida Department of Transportation, April 2005. [PDF 2.33 MB].
Best Practices Resources
Case Study 5 – Preliminary Design Stage Audit: Route 22/Spring Street Intersection – Upgrade; Westbrook, Maine
Michigan Intersection Safety Strategy and Near-Term Action Plan. January 2006. [PDF 294 KB]
Michigan’s intersection crash data parallels the national data. In 2002, the Governor’s Traffic Safety Advisory Commission (GTSAC) identified Intersection Safety as one of its three main issues to address. The GTSAC created an Intersection Safety Action Team and using the National Agenda as a guide developed the Michigan Intersection Safety Action Plan (ISAP). Issues and strategies from the National Agenda were carried forward into the Michigan Plan, as well as other issues and strategies not mentioned in the National Plan.
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