Turner-Fairbank Highway Research Center


Technical Summaries

Research reports are often summarized in executive summaries, technical briefs, or other abbreviated formats. Included here are those road safety summaries that involved research using HSIS data.

Title Pub Date Author Report Number
Safety Evaluation of Lane and Shoulder Width Combinations on Rural, Two-Lane, Undivided Roads May-09 FHWA FHWA-HRT-09-032
Two Low-Cost Safety Concepts for Two-Way STOP-Controlled, Rural Intersections on High-Speed Two-Lane Sep-08 Hughes, W., R. Jagannathan, and F. Gross FHWA-HRT-08-063
NCHRP Research Results Digest 329: Highway Safety Manual Data Needs Guide Jun-08 NCHRP
Safety Evaluation of Center Two-Way Left-Turn Lanes on Two-Lane Roads Mar-08 FHWA FHWA-HRT-08-046
Safety Evaluation of Flashing Beacons at Stop-Controlled Intersections Mar-08 FHWA FHWA-HRT-08-048
Safety Evaluation of STOP AHEAD Pavement Markings Mar-08 FHWA FHWA-HRT-08-045
NCHRP Research Results Digest 318: An Expert System for Recommending Speed Limits in Speed Zones May-07 NCHRP
NCHRP Research Results Digest 299: Crash Reduction Factors for Traffic Engineering and Intelligent T Nov-05 NCHRP

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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.

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