01769406

Monograph

http://www.trb.org/Main/Blurbs/181975.aspx

This report provides new proposed design guidance for the configuration of ditches adjacent to the roadway. The objective of this project was to develop guidelines for cost-effective design of roadside ditches that mitigate the severity of crashes on slopes by taking into consideration a more recent vehicle fleet. To meet this objective, the research team performed a detailed survey of state transportation agencies and a Canadian province to gather data on current practices for roadside ditch design. The survey was comprised of questions regarding the types of most common ditch configurations in the state, use of slope rounding, surface treatment, or other innovative practices for mitigating slope-related crashes. Although the survey did not identify a new mitigation method to reduce slope-related crashes, the results of the survey guided the research team in selecting values of some of the ditch design parameters for further evaluation through simulation analyses. In parallel to the survey, the research team evaluated and analyzed several existing crash databases. The objective was to identify any trends in the type and severity of ditch-related crashes and their relationship to ditch geometry, roadway characteristics, vehicle type, presence of appurtenances, and other relevant characteristics. An additional objective was to extract potentially useful data to support conducting a benefit-cost analysis (BCA) that would assist in developing ditch design guidelines. Based on the results of the initial literature review, survey of current practice, and analysis of existing crash data, the research team researched and subsequently devised a BCA method suitable for meeting the objectives of this project. Procedures to carry out the BCA method were developed to demonstrate feasibility, and the best available data to support the analysis were identified and obtained.

Submitted August 2020.

NCHRP Project 16-05

English

282p

2021

NCHRP Web-Only Document

9780309452694

Final Report

Digital/other

Appendices; Figures; Photos; References; Tables

Benefit cost analysis; Cost effectiveness; Crash data; Data analysis; Design; Ditches; Guidelines; Literature reviews; Roadside; Safety engineering; State of the practice

Design; Highways; Safety and Human Factors

TRIS, TRB, ATRI

Apr 2 2021 2:22PM