U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000


Skip to content U.S. Department of Transportation/Federal Highway AdministrationU.S. Department of Transportation/Federal Highway Administration

Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

 
Report
This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-RD-99-128
Date: October 1999

Crash Models for Rural Intersections: Four-Lane by Two-Lane Stop-Controlled and Two-lane by Two-lane Signalized

 

 

FOREWORD

This report provides direct input into the Accident Analysis Module (AAM) of the Interactive Highway Safety Design Model. The AAM is a tool that highway engineers can use to evaluate the impacts of highway design elements in project planning and preliminary design. Three crash models were developed relating crashes to three types of rural intersections. These types are: (1) three-legged intersections with major four-lane roads and minor two-lane roads that are stop-controlled, (2) four-legged intersections with major four-lane roads and minor two-lane roads that are stop-controlled, and (3) signalized intersections with both major and minor two-lane roads.

Elaborate sets of data were acquired from State data sources (Michigan and California) and collected in the field. The final data sets consist of 84 sites of three-legged intersections, 72 sites of the four-legged intersections, and 49 sites of the signalized intersections. Negative binomial models -- variants of Poisson models that allow for overdispersion -- were developed for each of the three data sets. Significant variables included major and minor road traffic; peak major and minor left-turn percentage; peak truck percentage; number of driveways; and channelization, intersection median widths, vertical alignment, and, in the case of signalized intersections, the presence or absence of protected left-turn phases. Separate models were developed for crashes resulting in injuries and total crashes.


Michael F. Trentacoste
Director, Office of Safety
Research and Development

 

Crash Models for Rural Intersections: Four-Lane

PDF Version (7.16 MB)

PDF files can be viewed with the Acrobat® Reader®

 


TECHNICAL REPORT DOCUMENTATION PAGE

1. Report No.

FHWA–RD–99–128

2. Government Accession No. 3. Recipient's Catalog No.
4. Title and Subtitle

Crash Models for Rural Intersections: Four–Lane by Two–lane Stop–Controlled and Two–lane by Two–lane Signalized

5. Report Date

October 1999

6. Performing Organization Code
7. Author(s)

Andrew Vogt

8. Performing Organization Report No.
9. Performing Organization Name and Address

Pragmatics, Inc.
7926 Jones Branch Drive, Suite 711
McLean, Virginia 22102

10. Work Unit No. (TRAIS)

3A5A

11. Contract or Grant No.

DTFH61–96–C–00076

12. Sponsoring Agency Name and Address

Office of Safety R&D
Federal Highway Administration
6300 Georgetown Pike, T-304
McLean, Virginia 22101-2296

13. Type of Report and Period Covered
14. Sponsoring Agency Code
15. Supplementary Notes

Contracting Officer's Technical Representative (COTR) - Joe G. Bared, HRDS

16. Abstract

This report describes the collection, analysis, and modeling of crash and roadway data for intersections on rural roads in California and Michigan for the years 1993–1995. Three classes of intersection are considered: (1) three–legged intersections with major four–lane roads and minor two–lane roads that are stop–controlled, (2) four–legged intersections with major four–lane roads and minor two–lane roads that are stop–controlled, and (3) signalized intersections with both major and minor two–lane roads. Data was acquired from the Highway Safety Information System, State and Federal photologs, and field work at all intersections. The field work included morning and evening traffic counts by movement and vehicle type as well as alignment measurements out to 800 feet (244 meters) along the major road. The final data sets consist of 84 three –legged intersections, 72 four–legged intersections, and 49 signalized intersections. Other variables collected include Roadside Hazard Rating, number of driveways, channelization, intersection angles, and speed limits.

Negative binomial models –– variants of Poisson models that allow for overdispersion –– were developed for each of the three data sets. Significant variables included major and minor road traffic, peak major and minor left–turn percentage, number of driveways, channelization, median widths, vertical alignment, and, in the case of signalized intersections, the presence or absence of protected left–turn phases and peak truck percentage. Models are developed for all crashes within 250 feet (76 meters) of the intersection center, for intersection–related crashes within 250 feet (76 meters), and for injury crashes. For injury crashes, intersection angle and minor road posted speed are significant. Models of crashes at signalized intersections by approach flows are also investigated, and other model forms are proposed for future consideration.

17. Key Words

Highway safety, crash prediction models, negative binomial regression, intersection design

18. Distribution Statement

No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161.

19. Security Classification (of this report)

Unclassified

20. Security Classification (of this page)

Unclassified

21. No. of Pages

182

22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized

 

FHWA-RD-99-128

ResearchFHWA
FHWA
United States Department of Transportation - Federal Highway Administration