Study Details

Study Title: Mini-Roundabout CMF Development

Authors: Pulugurtha et al.

Publication Date:MAY, 2021

Abstract: This research project focuses on quantifying the safety benefits of mini-roundabouts by developing crash modification factors (CMFs). Crash, traffic volume, and geometry data for 25 mini-roundabouts in eight states (Georgia, Iowa, Michigan, Minnesota, Missouri, North Carolina, Virginia, and Washington) was collected to conduct before and after analysis using the naïve method and the Empirical Bayes (EB) method. The results indicate a decrease in the number of total crashes and fatal and injury (FI) crashes when a two-way stop-controlled or one-way stop-controlled (TWSC or OWSC) intersection was converted to a mini-roundabout. However, the results indicate an increase in property damage only (PDO) crashes. Similarly, the results indicate an increase in the number of total crashes, FI crashes, and PDO crashes when an all-way stop-controlled (AWSC) intersection was converted to a mini-roundabout. The recommended CMFs for converting a TWSC/OWSC intersection to a mini-roundabout are 0.83 for total crashes, 0.41 for FI crashes, and 1.09 for PDO crashes. The recommended CMFs for converting an AWSC intersection to a mini-roundabout are 3.25 for total crashes, 1.74 for FI crashes, and 3.83 for PDO crashes.

Study Citation: Pulugurtha, S.S., R. Mishra, and S. Mathew. "Mini-Roundabout CMF Development." Report No. FHWA/NC/2020-32. North Carolina Department of Transportation. Raleigh, North Carolina. (May, 2021).

Comments: This Study has been replaced by Study 664 to better align countermeasure names with those presented to avoid confusion.

CMFs Associated With This Study

Category: Intersection geometry

Countermeasure: Convert Unsignalized Intersection to Mini-Roundabout

CMF	CRF(%)	Quality	Crash Type	Crash Severity	Roadway Type	Area Type
0.83	17		All	All	All	All

0.41	59		All	K,A,B,C	All	All

1.09	-9		All	O	All	All

3.25	-225		All	All	All	All

1.74	-74		All	K,A,B,C	All	All

3.83	-283		All	O	All	All

This site is funded by the U.S. Department of Transportation Federal Highway Administration
and maintained by the University of North Carolina Highway Safety Research Center

For more information, contact Sarah Weissman Pascual at sarah.pascual@dot.gov

The information contained in the Crash Modification Factors (CMF) Clearinghouse is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in the CMF Clearinghouse. The information contained in the CMF Clearinghouse does not constitute a standard, specification, or regulation, nor is it a substitute for sound engineering judgment.

CRASH MODIFICATION FACTORS CLEARINGHOUSE

Study Details

CMFs Associated With This Study

Category: Intersection geometry