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Roadside Intervention Effectiveness Model

The Roadside Intervention Effectiveness Model (RIEM) is based on the premise that interventions, such as roadside inspections and traffic enforcements, correct vehicle and driver violations thereby preventing crashes and injuries, and saving lives.

The RIEM relies on roadside inspection and traffic enforcement data collected by Safety Investigators. The Roadside Inspection Program evaluates roadside inspections, while the Traffic Enforcement Program evaluates traffic stops triggered by a moving violation. The RIEM associates each violation of the Federal Motor Carrier Safety Regulations (FMCSR) with a crash probability. Using these probabilities, analysts can estimate the number of crashes prevented as a result of correcting these violations.

A Note on Traffic Enforcement

As a result of FMCSA refining the list of codes inspectors use to identify violations, the number of traffic enforcement inspections has changed over time as non-moving violations were excluded from the RIEM. In 2009, several violations previously recorded as 392.2 – Local laws (general) were assigned new codes, such as miscellaneous drivers license violation (392.2DL), State vehicle registration or license plate violation (392.2RG), and wheel (mud) flaps missing or defective (392.2WC). These violations and others previously recorded under 392.2 do not meet the description of traffic enforcement being traffic stops triggered by observed driver behavior; therefore, they are not included in the count of traffic enforcement violations. Their exclusion has resulted in a reduction in the number of traffic enforcement inspections considered in the RIEM and, as a result, in an apparent reduction in the safety benefits attributed to traffic enforcement inspections.

A Note on RIEM Methodology

During 2018 FMCSA has initiated an evaluation of the RIEM technical methodology to consider potential model improvements. Further RIEM results will be released after completion of this evaluation, along with the evaluations findings and any adjustments to be made to the methodology.

To learn more about the RIEM and the effectiveness of roadside interventions and the Traffic Enforcement Program, view the RIEM reports found here.

–>View Model Reports
Roadside Intervention Effectiveness Model - National Results*
CY 2003CY 2004CY 2005FY 2006FY 2007FY 2008FY 2009FY 2010FY 2011FY 2012FY 2013
Total Interventions3,006,7853,013,6403,020,9053,273,0623,369,5173,479,7453,519,6443,560,3333,601,9413,581,9003,492,137
Roadside Inspections2,215,6692,210,8422,193,9542,372,8022,616,8682,723,5762,788,7282,849,3503,021,0023,065,689**3,089,760
Traffic Enforcement791,116802,798826,951900,260752,649756,169730,916710,983580,939516,211**402,377
Crashes Prevented15,42715,82016,78017,01516,87017,51716,93916,48414,77914,521**13,919
Roadside Inspections7,1767,3537,5757,5938,1018,4648,1498,1548,3118,585**9,904
Traffic Enforcement8,2518,4679,2059,4228,7699,0538,7898,3306,4685,936**4,015
Injuries Prevented11,73011,53511,63411,40510,87411,13710,82110,3699,0808,892**8,450
Roadside Inspections5,4565,3625,2525,0905,2225,3815,2065,1295,1065,257**6,012
Traffic Enforcement6,2746,1746,3826,3165,6525,7555,6145,2403,9743,635**2,438
Lives Saved681611624644638629573521484475**448
Roadside Inspections317284282287307304275258272281**319
Traffic Enforcement364327342357332325297263212194**129
*These results have been updated to reflect refinements to the Intervention Model, and hence do not necessarily correspond with results published in archived reports. A description of the model refinements can be found in Appendix A of the report FMCSA Safety Program Effectiveness Measurement: Intervention Model Fiscal Year 2009.
**FY 2012 interventions breakout and safety results were slightly revised per the RIEM FY 2013 Summary Report, incorporating updates to the FMCSA Traffic Enforcement Program’s violations list.
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