Document Use of Wider Edgelines in Iowa

Project Details
STATUS

In-Progress

PROJECT NUMBER

19-703

START DATE

05/15/19

END DATE

02/28/21

FOCUS AREAS

Safety

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Iowa Department of Transportation

Researchers
Principal Investigator
Shauna Hallmark

Director, InTrans

Co-Principal Investigator
Theresa Litteral

Statewide MDST Facilitator, LTAP

About the research

About 56% of traffic fatalities in the US are due to roadway departures. One strategy to address roadway departures is the use of a 6-inch versus 4-inch edge line. Use of the wider edge line is expected to increase conspicuity of the edge line, particularly in wet conditions. Additionally, the extra material may slow marking degradation due to increased surface cover making the edge line visible for a longer period of time.

Several CMFs for wider edge lines were available through the Crash Modification Factor (CMF) Clearinghouse. CMFs ranged from 0.53 to 0.96 depending on crash type. However, the CMFs were derived from a single study in Texas.

The cost of installation is expected to be around 33% over the cost of regular edge lines. As a result, additional information on the effectiveness of wider edgelines would be helpful to assist agencies in programming safety funds.

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