Turner-Fairbank Highway Research Center


HSIS Summaries

HSIS Summary Reports are two to eight pages in length and include a brief description of the issue addressed, data used, methodology applied, significant results, and practical implications.

Title Pub Date Author Report Number
Safety Effects of the Conversion of Rural Two-Lane Roadways to Four-Lane Roadways Nov-99 Forrest M. Council and J. Richard Stewart FHWA-RD-99-206
Using GIS in the Analysis of Truck Crashes Jun-99 David Harkey FHWA-RD-99-119
GIS-Based Crash Referencing and Analysis System Feb-99 David L. Harkey FHWA-RD-99-081
Effects of a Towaway Reporting Threshold on Crash Analysis Results Aug-98 Charles V. Zegeer, Herman F. Huang, J. Richard Stewart, Ron Pfefer, Jun Wang FHWA-RD-98-114
Investigation of National Highway System Roadways in the HSIS States Apr-98 Charles V. Zegeer, Herman F. Huang, J. Richard Stewart, and Carolyn Williams FHWA-RD-98-080
The Effects of Airbags on Severity Indices for Roadside Objects Feb-98 Forrest M. Council, J. Richard Stewart, and Yusuf M. Mohamedshah FHWA-RD-98-056
Safety Effects of Cross-Section Design on Rural Multilane Highways Jun-97 Jun Wang, Warren E. Hughes, and Richard Stewart FHWA-RD-97-027
Investigation of Highway Work Zone Crashes: What We Know and What We Don't Know Oct-96 Jun Wang, Warren E. Hughes, Forrest M. Council, and Jeffrey F. Paniati FHWA-RD-96-100
Analysis of Older Drivers On Freeways Aug-96 David L. Harkey, Herman Huang, and Charles V. Zegeer FHWA-RD-96-035
Comparison of the Safety of Lighting Options on Urban Freeway May-95 Michael S. Griffith FHWA-RD-94-188
Investigation of Crashes with Animals Mar-95 Warren E. Hughes and Reza Saremi FHWA-RD-94-156
The Application of an Improved Accident Analysis Method for Highway Safety Evaluations Oct-94 Jun Wang FHWA-RD-94-082
The Magnitude and Severity of Passing Accidents on Two-Lane Rural Roads Nov-94 FHWA-RD-94-068
Accident Relationships of Roadway Widths on Low-Volume Roads Jun-94 Charles V. Zegeer FHWA-RD-94-023
Truck Accident Models Aug-94 FHWA-RD-94-022
Accident Analysis of Older Drivers at Intersections Feb-95 FHWA-RD-94-021
The Association of Median Width and Highway Accident Rate Aug-93 Matthew W. Knuiman, Forrest M. Council, and Donald W. Reinfurt FHWA-RD-93-046
Analysis of Commercial Bus Crashes Nov-92 Charles V. Zegeer (HSRC) FHWA-RD-93-018
Review of the Impacts of the Towaway Reporting Threshold on a Highway Safety Program Jul-01 Lacy, K., C. Zegeer, and R. Schneider FHWA-RD-01-114
Association of Selected Intersection Factors with Red-Light-Running Crashes May-00 Yusuf M. Mohamedshah, Li Wan Chen, and Forrest M. Council FHWA-RD-00-112

Show items on each page

previous 1 2 

Search Products

Safety Effects of Horizontal Curve and Grade Combinations on Rural Two-Lane Highways

The safety effects of horizontal curves and grades on rural two-lane highways have been quantified in the American Association of State Highway and Transportation Officials (AASHTO) Highway Safety Manual (HSM), but it was not previously known whether and how the safety performance of horizontal curves and grades interact. Furthermore, there are no established safety effects for crest and sag vertical curves, and it is unknown whether and how the safety performance of crest or sag vertical curves is affected by the presence of horizontal curves.

The objective of this study was to quantify the combined safety effects of horizontal curves and grade combinations and express the results as crash modification factors (CMFs) that can be considered for use in the AASHTO HSM.

Download PDF version
View HTML version


Download the Excel calculator tool here.


Highlighted Products

Safety Evaluation of Converting Traffic Signals from Incandescent to Light-Emitting Diodes

Across the Nation, many agencies have been replacing conventional incandescent light bulbs in traffic signals with light-emitting diodes (LED). LEDs are primarily installed to reduce energy consumption and decrease maintenance. In addition, LEDs are expected to last much longer compared with incandescent bulbs and tend to age gradually. However, a recent study revealed several potential problems with LEDs, including their inability to melt snow and issues related to visual discomfort caused by glare at night.

Download PDF version
View HTML version


Safety Evaluation Of Discontinuing Late-Night Flash Operations at Signalized Intersections

During late-night flash (LNF) mode (from late night to early morning hours), traffic signals flash yellow for one road (typically, the major road), requiring caution but no stopping, and flash red for the other road (typically, the minor road), requiring drivers to stop and then proceed through the intersection after yielding to the traffic on the major road. The intent of LNF is to reduce energy consumption and delay during periods of low traffic demand. However, in recent years, many agencies have begun replacing LNF with normal phasing operation because of safety concerns.

Download PDF version
View HTML version