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FHWA Home / Safety / Pedestrian & Bicycle / Toolbox of Countermeasures and Their Potential Effectiveness

Toolbox of Countermeasures and Their Potential Effectiveness

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FHWA-SA-018-41
September 2018

Introduction

A CMF is the proportion of crashes that are expected to remain after the countermeasure is implemented. For example, an expected 20 percent reduction in crashes would correspond to a CMF of (1.00 – 0.20) = 0.80. In some cases, the CMF is negative, i.e. the implementation of a countermeasure is expected to lead to a percentage increase in crashes.

One CMF estimate is provided for each countermeasure. Where multiple CMF estimates were available from the literature, selection criteria were used to choose which CMFs to include in the issue brief:

Crash Reduction Factors

A CRF is the percentage crash reduction that might be expected after implementing a given countermeasure. In some cases, the CRF is negative, i.e. the implementation of a countermeasure is expected to lead to a percentage increase in crashes.

One CRF estimate is provided for each countermeasure. Where multiple CRF estimates were available from the literature, selection criteria were used to choose which CRFs to include in the issue brief:

Where these criteria could not be met, a CMF may still be provided. In these cases, it is recognized that the estimate of the CMF may not be as reliable, but is the best available at this time. The CMFs in this issue brief may be periodically updated as new information becomes available.

The Desktop Reference for Countermeasures includes most of the CMFs included in this issue brief, and adds many other CMFs available in the literature. A few CMFs found in the literature were not included in the Desktop Reference. Those excluded CMFs were considered to have smaller sample sizes or too large a standard error to be meaningful, or the original research did not provide sufficient detail for the CMF to be useful.

A CMF should be regarded as a generic estimate of the effectiveness of a countermeasure. The estimate is a useful guide, but it remains necessary to apply engineering judgment and to consider site-specific environmental, traffic volume, traffic mix, geometric, and operational conditions which will affect the safety impact of a countermeasure. Actual effectiveness will vary from site to site. The user must ensure that a countermeasure applies to the particular conditions being considered. The reader is also encouraged to obtain and review the original source documents for more detailed information, and to search databases such as the National Transportation Library (ntlsearch.bts.gov) for information that becomes available after the publication of this issue brief.

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Using the Tables

The CRFs for pedestrian crashes are presented in three tables which summarize the available information. The Tables are:

Each table has the following columns:

Cells with "—" indicate that no information is reported in the source document. For additional information, visit the FHWA Office of Safety website (safety.fhwa.dot.gov).

Example

  COUNTERMEASURE CRASH SEVERITY CMF FOR CRASH TYPE (SE) REFERENCE NUMBER CMF ID STAR RATING
ALL LEFT TURN PEDESTRIAN
Exclusive Pedestrian Phase   All 0.49
(0.16)
  2   4117   2

Using the first countermeasure from Table 1 as an example, the following information can be gained from the table:

  1. The countermeasure name is "Exclusive Pedestrian Phase."
  2. The crash severity is "All," meaning that the original study calculated the CMF for all crash severities combined or did not specify a crash severity.
  3. A CMF of 0.49 is listed under the "Pedestrian" column, meaning that a (1.00 - 0.49) = 51% reduction in pedestrian crashes is expected for this countermeasure.
  4. The "—" in the "All" and "Left-Turn" columns indicates that CMFs for these crash types were not provided in the original study.
  5. The standard error for this CMF is 0.16.
  6. The reference number is 2, which refers to the 2012 study by Chen, Chen, Ewing, McKnight, Srinivasan, and Roe in the references list.
  7. The CMF ID is 4117 in the CMF Clearinghouse.
  8. This study has a 2 star rating.

Other Useful Resources

TABLE 1. SIGNALIZED COUNTERMEASURES

  COUNTERMEASURE CRASH SEVERITY CMF FOR CRASH TYPE (SE) REFERENCE NUMBER CMF ID STAR RATING
ALL LEFT TURN PEDESTRIAN
Exclusive Pedestrian Phase All 0.49
(0.16)
2 4117 2
Improved Signal Timing (ITE) Fatal/Injury 0.63 14 383 2
Replace Existing "Walk/ Don't Walk" Signals with Pedestrian Countdown Signal Head All 0.75 9
Replace Existing "Walk/ Don't Walk" Signals with Pedestrian Countdown Signal Head All 0.3 15 5272 4
Implement Leading Pedestrian Interval (LPI) All 0.413
(0.064)
4 1993 3
Remove Unwarranted Signals (One-Way Street) All 0.83 12 331 3
Pedestrian Hybrid Beacon (PHB) All 0.45
(0.167)
17 9020 4
PHB and Advanced Yield/Stop Markings/ Signs All 0.43
(0.134)
17 9021 4
Increase Pedestrian Crossing Time All 0.49
(0.10)
2 4658 3
Add New Traffc Signals, when Warranted All 0.75
(0.07)
2 4658 3

 

TABLE 2. GEOMETRIC COUNTERMEASURES

  COUNTERMEASURE CRASH SEVERITY CMF FOR CRASH TYPE (SE) REFERENCE NUMBER CMF ID STAR RATING
ALL LEFT TURN PEDESTRIAN
Install Pedestrian Overpass/Underpass Fatal/Injury 0.1 6
Install Pedestrian Overpass/Underpass All 0.14 6
Install Pedestrian Overpass/Underpass (Unsignalized Intersection) All 0.87 8
Install Raised Median All 0.75 6
Install Raised Median at Unsignalized Crossing All 0.69
(0.183)
17 8799 3
Install Raised Pedestrian Crossing All 0.7 1
Install Raised Pedestrian Crossing Fatal/Injury 0.64 1
Install Sidewalk All 0.12 10
Provide Paved Shoulder All 0.29 6
Narrow Roadway from Four Lanes to Three Lanes (Two Through Lanes with Center Turn Lane) All 0.71 7 199 5
Road Diet–Urban Area All 0.81
(0.005)
11 5554 4
Road Diet–Suburban Area All 0.53
(0.02)
12 2841 4

 

TABLE 3. SIGNS, MARKINGS, AND OPERATIONAL COUNTERMEASURES

  COUNTERMEASURE CRASH SEVERITY CMF FOR CRASH TYPE (SE) REFERENCE NUMBER CMF ID STAR RATING
ALL LEFT TURN PEDESTRIAN
Add Overhead Lighting Injury Crashes 0.77 7 199 5
Improve Pavement Friction (Skid Treatment with Overlay) Fatal/Injury 0.97 6
Increase Enforcement All 0.77 16
Prohibit Right-Turn-on- Red All 0.97 7 199 5
Prohibit Left Turns All 0.9 6
Restrict Parking Near Intersections (to Off- Street) All 0.7 6
High-Visibility Crosswalk All 0.52
(0.17)
2 4658 3
Convert Parallel Lane to High-Visibility Crosswalk (School Zone) All 0.63 5 2697 3
Advanced Stop/Yield All 0.75
(0.230)
17 9017 3
Rectangular Rapid- Flashing Beacon (RRFB) All 0.53
(0.377)
17 9024 2

References

  1. Bahar, G., Parkhill, M., Hauer, E., Council, F., Persaud, B., Zegeer, C., Elvik, R., Smiley, A., and Scott, B. "Prepare Parts I and II of a Highway Safety Manual: Knowledge Base for Part II". Unpublished material from NCHRP Project 17-27, (May 2007).
  2. Chen, L., C. Chen, R. Ewing, C. McKnight, R. Srinivasan, and M. Roe. Safety Countermeasures and Crash Reduction in New York City&mash;Experience and Lessons Learned. Accident Analysis and Prevention. In print, 2012. Retrieved July 23, 2012.
  3. De Brabander, B. and Vereeck, L., "Safety Effects of Roundabouts in Flanders: Signal type, speed limits and vulnerable road users." AAP-1407, Elsevier Science, (2006).
  4. Fayish, A.C. and F. Gross, "Safety Effectiveness of Leading Pedestrian Intervals Evaluated by a Before—After Study with Comparison Groups." Transportation Research Record: Journal of the Transportation Research Board, No. 2198, Transportation Research Board of the National Academies, Washington, D.C., 2010, pp. 15-22. DOI: 10.3141/2198-03
  5. Feldman, M., J. Manzi, and M. Mitman. "An Empiracal Bayesian Evaluation of the Safety Effects of High-Visibility School (Yellow) Crosswalks in San Francisco, California." Transportation Research Record: Journal of the Transportation Research Board, No. 2198, Transportation Research Board, Washington, D.C., 2010, pp. 8-14.
  6. Gan, A., Shen, J., and Rodriguez, A., "Update of Florida Crash Reduction Factors and Countermeasures to improve the Development of District Safety Improvement Projects." Florida Department of Transportation, (2005).
  7. Harkey, D. et al., "Crash Reduction Factors for Traffc Engineering and ITS Improvements," NCHRP Report No. 617, (2008).
  8. Institute of Transportation Engineers, "Toolbox of Countermeasures and Their Potential Effectiveness to Make Intersections Safer." Briefng Sheet 8, ITE, FHWA, (2004).
  9. Markowitz, F., Sciortino, S., Fleck, J. L., and Yee, B. M., "Pedestrian Countdown Signals: Experience with an Extensive Pilot Installation." Institute of Transportation Engineers Journal, Vol. January 2006, ITE, (1-1-2006) pp. 43-48. Updated by Memorandum, Olea, R., "Collision changes 2002-2004 and countdown signals," (February 7th, 2006).
  10. McMahon, P., Zegeer, C., Duncan, C., Knoblauch, R., Stewart, R., and Khattak, A., "An Analysis of Factors Contributing to ‘Walking Along Roadway’ Crashes: Research Study and Guidelines for Sidewalks and Walkways," FHWA-RD-01-101, (March 2002)
Page last modified on October 16, 2018
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