Evaluation of Dynamic Speed Feedback Signs on Curves: A National Demonstration Project

Hallmark, Shauna; Hawkins, Neal; Smadi, Omar; Iowa State University. Center for Transportation Research and Education

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Evaluation of Dynamic Speed Feedback Signs on Curves: A National Demonstration Project

2015-01-01
By Hallmark, Shauna ; Hawkins, Neal ; Smadi, Omar

[PDF-4.99 MB]

English

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Creators:

Hallmark, Shauna ; Hawkins, Neal ; Smadi, Omar

Hallmark, Shauna ; Hawkins, Neal ; Smadi, Omar Less -
Corporate Creators:

Iowa State University. Center for Transportation Research and Education
Corporate Contributors:

Midwest Transportation Consortium ; United States. Federal Highway Administration ; Iowa Highway Research Board ; Texas Dept. of Transportation

Midwest Transportation Consortium ; United States. Federal Highway Administration ; Iowa Highway Research Board ; Texas Dept. of Transportation Less -
Subject/TRT Terms:

[+]

85th Percentile Speed Before And After Studies Crash Mitigation Curve Speed Safety Demonstration Projects Evaluation Highway Curves Highways Horizontal Curves I73: Traffic Control I83: Accidents And The Human Factor Lane Position Low-cost Safety Improvements Operations And Traffic Management Rural Highways Rural Road Safety Safety And Human Factors Speed-activated Displays Speed Control Speed Signs Speed Warning Signs
Publication/ Report Number:

FHWA-HRT-14-020;IHRB Project TR-579;InTrans Project 08-320
Resource Type:

Tech Report
Geographical Coverage:

United States;Iowa
TRIS Online Accession Number:

01554383
Edition:

Final Report
Corporate Publisher:

United States. Federal Highway Administration
Abstract:

Lane departure crashes are a significant safety concern. The majority of lane departure crashes occur on rural two-lane roadways, with a disproportionate number of these crashes on horizontal curves. Curve-related crashes involve a number of roadway and driver causative factors. A primary driver factor is speeding. Dynamic speed feedback sign (DSFS) systems are one method to reduce vehicle speeds and, consequently, crashes on curves. These systems show promise but they have not been fully evaluated on curves. The Center for Transportation Research and Education at Iowa State University conducted a national demonstration project to evaluate the effectiveness of two different DSFSs in reducing speed and crashes on curves at 22 total sites on rural two-lane roadways in seven States. The goal is to provide traffic safety engineers and other professionals with additional tools to manage speeds and crashes on rural horizontal curves more effectively. Data were collected before and at 1, 12, and 24 months after installation of the DSFS. On average, most sites had decreases in mean speeds, with decreases up to 10.9 miles per hour (mph) noted for both the point of curvature (PC) and center of curve (CC). Most sites experienced changes in 85th percentile speed of 3 mph or more at the PC, with the majority of sites having a decrease of 2 mph at the CC. The numbers of vehicles traveling 5, 10, 15, or 20 mph over the posted or advisory speed limit were also compared. Large reductions in the number of vehicles traveling over the posted or advisory speed occurred for all of the after periods at the PC and CC, indicating that the signs were effective in reducing high-end speeds, as well as average and 85th percentile speeds. A before-and-after crash analysis was also conducted, and crash modification factors (CMF) were developed. CMFs ranged from 0.93 to 0.95 depending on the crash type and direction of the crash.
Format:

PDF
Funding:

DTFH61-07-H-00022
Collection(s):

Federal Highway Administration University Transportation Centers
Main Document Checksum:

[+]

urn:sha256:9b77ba6ec5f61518afe637142c8d8efc6eba5154f9f57b7fbbec5a254f815210
Download URL:

https://rosap.ntl.bts.gov/view/dot/36546/dot_36546_DS1.pdf
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Evaluation of Dynamic Speed Feedback Signs on Curves: A National Demonstration Project

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