CTRE is an Iowa State University center, administered by the Institute for Transportation.

Address: 2711 S. Loop Drive, Suite 4700, Ames, IA 50010-8664

Phone: 515-294-8103
FAX: 515-294-0467

Website: www.ctre.iastate.edu/

Iowa State University--Becoming the Best

MnDOT Evaluation of Intersection Conflict Warning Systems


Principal investigators:

Co-principal investigators:

Project status

In progress

Start date: 06/30/14
End date: 08/31/17


Sponsor(s): Minnesota Department of Transportation

About the research


Rural intersections account for 30% of crashes in rural areas and 6% of all fatal crashes. One unique and promising solution has been to use intersection conflict warning systems (ICWSs) at the minor approach of stop-controlled intersections. Early studies indicate lower intersection approach speeds, reduced conflicts, improved compliance with traffic control, and improved gap selection. Simple before and after crash analyses have indicated reductions in total crashes up to 46% and severe crashes up to 72%. However, there has been some evidence of increased roll-throughs, and some sites have experienced minor crash increases.
Although ICWSs show promise, their effectiveness has not been well established. Since robust crash analyses are not yet available, it is desirable to evaluate the systems using crash surrogates so that further investments can be considered. In addition, the influence of ICWSs on adjacent intersections has not been considered. As a result, the objectives of this research are to evaluate driver behavior at mainline and stop-controlled approaches for intersections with and without ICWSs and develop an assessment of the traffic volume range and limits where the system is nearly continuously activated and is likely to lose its effectiveness.