Roundabout Safety Prediction

The documents provided on this webpage were developed for NCHRP Project 17-70: Development of Roundabout Crash Prediction Models and Methods.  They represent the original work products that document the development of the intersection-level roundabout crash prediction models. The contents of these documents have been reproduced in the project final report (which is available from NCHRP).

Intersection-level models are used to predict the average frequency and severity of crashes associated with the overall roundabout, regardless of whether the crash occurs within the roundabout or on one of its legs. These models are envisioned to be used for design applications and, as such,  include several crash modification factors (CMFs) that can be used to adjust the predicted crash frequency to reflect the safety influence of existing or proposed roundabout design elements.

Implementation Products

Intersection-Level Safety Prediction Method. This document presents the intersection-level safety prediction method. It describes step-by-step procedures for computing the predicted frequency of roundabout-related crashes by crash type and severity category.  PROCEDURE GUIDE

Research Reports

Working Paper No. 4.4 - Intersection-Level Roundabout Models: Calibrated Crash Frequency Prediction Models. This paper describes the activities undertaken to develop intersection-level models for predicting crash frequency.  REPORT

Working Paper No. 4.5 - Intersection-Level Roundabout Models: Calibrated Severity Distribution Prediction Model. This paper describes the activities undertaken to develop (1) a model for predicting the severity distribution proportions and (2) a table of crash type distribution proportions.  REPORT