01691793

Monograph

http://www.trb.org/Main/Blurbs/178663.aspx

Safety performance factors (SPFs) and crash modification factors (CMFs) are predictive models that estimate expected crash frequencies. Transportation professionals use these models to identify locations where crash rates are higher than expected, to estimate safety benefits of a proposed project, and to compare the safety benefits of design alternatives. The models help identify and prioritize locations for safety improvements, compare project alternatives by their expected safety benefits, and guide detailed design decisions to optimize safety. Research indicates that roundabouts provide substantial reductions in crashes, especially crashes that result in serious injuries or fatalities. However, the first edition of the HSM did not include a crash prediction method for roundabouts; therefore, practitioners were not able to quantitatively assess the crash reduction benefits of providing a roundabout at a specific intersection or to investigate the safety effects of complex design decisions at singlelane and multilane roundabouts. This report provides practitioners with SPFs and CMFs for roundabouts. The models include variables for geometric features and operational characteristics, as well as their expected effects on crash rates for motorized and nonmotorized users. The models can be used for planning-level analysis, and, as a project develops and more detailed information is available, for analysis at the intersection level and leg level of an intersection.

Project 17-70

English

187p

2018

NCHRP Research Report

9780309480048

Digital/other

Bibliography; Figures; References; Tables

Crash modification factors; Crash rates; Crash risk forecasting; Geometric segments; Highway safety; Mathematical prediction; Roundabouts

Highway Safety Manual

Design; Highways; Safety and Human Factors

TRIS, TRB, ATRI

Jan 29 2019 10:29AM