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Planning Guidance for the Installation and Use of Technology Devices for Transportation Operations and Maintenance

ENTERPRISE Transportation Pooled Fund Study


ICWS Guideline 2 - Intersection Characteristics (Proactive Approach)

Purpose: To influence driver behavior at stop-controlled intersections (typically 45 mph or greater posted speed on the major road) where conditions are such that the intersection could be susceptible to right-angle crashes.

Initial Guidance:

1) The planning guidance provides guidance for the use of an ICWS device, regardless of the device configuration. If an ICWS should be considered, the device configuration will be selected by the engineer. (Note: Design guidance for ICWS developed by ENTERPRISE and other relevant resources can be found at: Design and Evaluation Guidance for Intersection Conflict Warning Systems)

2) This guideline does not mandate the use of ICWS. ICWS is one of several safety treatments that may be considered to improve safety at intersections.

3) ICWS #1 Intersections with High Frequencies or Crash Rates (Reactive Approach) and ICWS #2 Intersection Characteristics (Proactive Approach) may be used together or as stand-alone approaches for consideration of ICWS. Intersections meeting guideline criteria may not necessarily be selected for deployment of ICWS; these guidelines could be used to help agencies prioritize intersections for ICWS deployment.

4) To optimize the effectiveness of ICWS by reducing the likelihood of continuous alert activation, the following maximum ADT volumes should be considered:

  • Major Road ADT typically does not exceed 12,000. (1)
  • Minor Road ADT typically does not exceed 3,000. (1)

5) Engineering judgment should be used to assess potential implications that may result from installation of ICWS at candidate intersections.


(1) Athey Creek Consultants.  Design Guidance and Evaluation for Intersection Conflict Warning Systems. 2011.


  Device should be considered if:  

1. One or both of the  following conditions is observed at the intersection:

a) Limited sight distance


b) Poor gap acceptance for the minor road driver is observed at the site (e.g. actual crashes and/or near misses)


2. One or more of the following conditions are present at the intersection. These conditions have been found to be associated with a higher frequency of right-angle crashes at stop-controlled intersections. (1) The combination of conditions present at the intersection should be assessed using engineering judgment.

  • The intersection skew angle is greater than 15 degrees. (1)
  • A horizontal curve and/or vertical curve is present at the intersection. (1) (2)
  • A railroad crossing is present on one of the minor leg approaches to the intersection. (3)
  • Commercial development is present in one or more of the intersection quadrants. (45)
  • The minor leg approach does not have a STOP sign within 5 miles prior to the intersection. (5)
  • Crashes or Crash Rate at the intersection are trending higher than expected over a 5-year period for a region.


(1) CH2M HILL and SRF Consulting Group, Inc. Otter Tail County: County Roadway Safety Plan. 2011.

(2) Preston, Howard.  Intersection Safety Analysis Update Final Report.  Minnesota Department of Transportation. 2009.

(3) CH2M HILL. MnDOT District 3 – 13 County Road Safety Audit Review, Final Technical Report.  Minnesota Department of Transportation. 2006.

(4) Maze, T.H., Hawkins, Neal R., and Burchett, Garrett.  Rural Expressway Intersections Synthesis of Practice and Crash Analysis. Iowa State University, CTRE Project 03-157. 2004.

(5) Harder, Kathleen A., Bloomfield, John, and Chihak, Benjamin J.  Reducing Crashes at Controlled Rural Intersections. University of Minnesota. 2003.

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