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.
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.
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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.
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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.
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Safety Effects of Horizontal Curve and Grade Combinations on Rural Two-Lane Highways | January | FHWA-HRT-13-078 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Safety Evaluation of Converting Traffic Signals from Incandescent to Light-Emitting Diodes | August | Raghavan Srinivasan, Daniel Carter, Sarah Smith, Bo Lan | FHWA-HRT-13-070 |
| Safety Evaluation Of Discontinuing Late-Night Flash Operations at Signalized Intersections | August | Bo Lan, Raghavan Srinivasan | FHWA-HRT-13-069 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Safety Evaluation of Transverse Rumble Strips on Approaches to Stop-Controlled Intersections in Rural Areas | May | Srinivasan, R., J. Baek, and F. Council | FHWA-HRT-12-047 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Safety Evaluation of the Safety Edge Treatment | January | Graham, J., K. Richard, M. O’Laughlin, and D. Harwood | FHWA-HRT-11-025 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Evaluation of Lane Reduction "Road Diet" Measures on Crashes | June | Persaud, B. and C. Lyon | FHWA-HRT-10-053 |
| Factors Contributing to Pedestrian and Bicycle Crashes on Rural Highways | June | Carter, D. and F. Council | FHWA-HRT-10-052 |
| Development of a Speeding-Related Crash Typology | May | Council, F.M., R. Srinivasan, S. Masten, D. Carter, and M. Reurings | FHWA-HRT-10-039 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Safety Effects of Using Narrow Lanes and Shoulder-Use Lanes to Increase the Capacity of Urban Freeways | June | Bauer, K.M., D.W. Harwood, K.R. Richard, and W.E. Hughes | FHWA-HRT-05-001 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| An Examination of Fault, Unsafe Driving Acts, and Total Harm in Car-Truck Collisions | June | Council, F.M., D.L. Harkey, D.T. Nabors, A.J. Khattak, and Y.M. Mohamedshah | FHWA-HRT-04-085 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Review of the Impacts of the Towaway Reporting Threshold on a Highway Safety Program | July | Lacy, K., C. Zegeer, and R. Schneider | FHWA-RD-01-114 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Association of Selected Intersection Factors with Red-Light-Running Crashes | May | Yusuf M. Mohamedshah, Li Wan Chen, and Forrest M. Council | FHWA-RD-00-112 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Safety Evaluation of Rolled-in Continuous Shoulder Rumble Strips Installed on Freeways | December | Michael S. Griffith | FHWA-RD-00-032 |
| Safety Effects of the Conversion of Rural Two-Lane Roadways to Four-Lane Roadways | November | Forrest M. Council and J. Richard Stewart | FHWA-RD-99-206 |
| Using GIS in the Analysis of Truck Crashes | June | David Harkey | FHWA-RD-99-119 |
| GIS-Based Crash Referencing and Analysis System | February | David L. Harkey | FHWA-RD-99-081 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Effects of a Towaway Reporting Threshold on Crash Analysis Results | August | 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 | April | 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 | February | Forrest M. Council, J. Richard Stewart, and Yusuf M. Mohamedshah | FHWA-RD-98-056 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Safety Effects of Cross-Section Design on Rural Multilane Highways | June | Jun Wang, Warren E. Hughes, and Richard Stewart | FHWA-RD-97-027 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Investigation of Highway Work Zone Crashes: What We Know and What We Don't Know | October | Jun Wang, Warren E. Hughes, Forrest M. Council, and Jeffrey F. Paniati | FHWA-RD-96-100 |
| Accident Analysis of Older Drivers On Freeways | August | David L. Harkey, Herman Huang, and Charles V. Zegeer | FHWA-RD-96-035 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Comparison of the Safety of Lighting Options on Urban Freeway | May | Michael S. Griffith | FHWA-RD-94-188 |
| Investigation of Crashes with Animals | March | Warren E. Hughes and Reza Saremi | FHWA-RD-94-156 |
| Accident Analysis of Older Drivers at Intersections | February | FHWA-RD-94-021 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| The Magnitude and Severity of Passing Accidents on Two-Lane Rural Roads | November | FHWA-RD-94-068 | |
| The Application of an Improved Accident Analysis Method for Highway Safety Evaluations | October | Jun Wang | FHWA-RD-94-082 |
| Truck Accident Models | August | FHWA-RD-94-022 | |
| Accident Relationships of Roadway Widths on Low-Volume Roads | June | Charles V. Zegeer | FHWA-RD-94-023 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| The Association of Median Width and Highway Accident Rate | August | Matthew W. Knuiman, Forrest M. Council, and Donald W. Reinfurt | FHWA-RD-93-046 |
| Title | Publication Date | Author | Report Number |
|---|---|---|---|
| Analysis of Commercial Bus Crashes | November | Charles V. Zegeer (HSRC) | FHWA-RD-93-018 |
Last updated: Tuesday, July 18, 2023