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Title:

Upgrading Bridge Rails on Low-Volume Roads in Iowa

Accession Number:

01626525

Record Type:

Component

Abstract:

Building on previous research, the goal of this project was to identify significant influencing factors for the Iowa Department of Transportation (DOT) to consider in future updates of its Instructional Memorandum (I.M.) 3.213, which provides guidelines for determining the need for traffic barriers (guardrail and bridge rail) at secondary roadway bridges. A literature review of policies and guidelines in other states and, specifically, of studies related to traffic barrier safety countermeasures at bridges were conducted. In addition, a safety impact study was conducted to evaluate possible non-driver-related behavior characteristics of crashes on secondary road structures in Iowa using road data, structure data, and crash data from 2004 to 2013. Statistical models were used to determine significant factors in regard to crash volume and crash severity. The study found that crashes are somewhat more frequent on/at bridges possessing certain characteristics—high traffic volumes, long bridge lengths, bridge width narrower than its approach or narrower than 20 ft., and bridges older than 25 years. No specific roadway or bridge characteristic was found to contribute to more serious crashes. The study also confirmed previous research findings that crashes with bridges on secondary roads are rare, low-severity events. Although the findings of the study support the need for appropriate use of bridge rails, it concludes that prescriptive guidelines for bridge rail use on secondary roads may not be necessary, given the limited crash expectancy and lack of differences in crash expectancy among the various combinations of explanatory characteristics.

Supplemental Notes:

This paper was sponsored by TRB committee AFB30 Standing Committee on Low-Volume Roads.

Monograph Accession #:

01618707

Report/Paper Numbers:

17-03412

Language:

English

Corporate Authors:

Transportation Research Board

500 Fifth Street, NW
Washington, DC 20001 United States

Authors:

Nketah, Emmanuel
Bektas, Basak
Hans, Zachary
Fox, Nicole

Pagination:

21p

Publication Date:

2017

Conference:

Transportation Research Board 96th Annual Meeting

Location: Washington DC, United States
Date: 2017-1-8 to 2017-1-12
Sponsors: Transportation Research Board

Media Type:

Digital/other

Features:

References; Tables

Geographic Terms:

Iowa

Subject Areas:

Bridges and other structures; Design; Highways; Policy; Safety and Human Factors

Source Data:

Transportation Research Board Annual Meeting 2017 Paper #17-03412

Files:

TRIS, TRB, ATRI

Created Date:

Dec 8 2016 11:17AM