An Examination of Washington State’s Vehicle Impoundment Law for Motorcycle Endorsements

McKnight, A. Scott; Billheimer, John W.; Tippetts, Scott · 2013 · ROSA P / United States. Department of Transportation. National Highway Traffic Safety Administration

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Summary

This study evaluates the impact of Washington State’s 2007 vehicle impoundment law, which authorized law enforcement to impound motorcycles operated by riders lacking a proper motorcycle endorsement. The research was motivated by a nearly 300% increase in fatal motorcycle crashes in Washington between 1997 and 2006, alongside national concerns regarding the high proportion of unendorsed riders involved in crashes. Unendorsed riding is correlated with risky behaviors such as speeding and alcohol use. The study aimed to determine if the impoundment law improved implementation, increased awareness, boosted endorsement and training rates, and reduced crash rates. The researchers employed a mixed-methods approach using data collected between September 2009 and December 2011. Qualitative data were gathered through interviews with state officials, law enforcement, towing companies, and motorcycle club representatives, as well as internet and news media searches. A rider survey conducted at a Seattle motorcycle show assessed awareness and opinions of the law. Quantitative analysis utilized Washington State enforcement, crash, and licensing records. Time-series analyses using ARIMA intervention models were applied to assess changes in endorsements, training, and crashes, controlling for economic factors like unemployment rates. Findings indicated that the law caused no unforeseen implementation problems for law enforcement or towing agencies, though impoundments were infrequent due to low detection rates and officer reluctance. Awareness of the law was widespread among law enforcement and many riders, with 56% of surveyed riders correctly identifying the law; however, awareness was lower in rural areas. Enforcement data showed no significant change in citations for unendorsed riding. Time-series analyses revealed no statistically significant increase in new endorsements or total endorsements, nor a significant reduction in overall crash rates. However, there was a significant 10.8% increase in the ratio of riders using safety training waivers versus licensing station tests, suggesting the law may have made training more attractive. Additionally, the proportion of crashes involving unendorsed riders decreased significantly by 21.9%, though this finding was inconclusive due to confounding economic factors that also reduced overall riding and crash rates. The study concludes that while the impoundment law did not significantly increase endorsement rates or reduce overall crashes, it may have shifted rider behavior toward safety training. The lack of significant endorsement increases suggests that the law did not drive a large volume of unendorsed riders to obtain licenses, or that economic downturns masked these effects. The significant drop in crashes involving unendorsed riders implies either a shift in the rider population or reduced exposure for unendorsed riders. The authors note that the law’s effectiveness is difficult to isolate from broader economic trends, but it appears to have been implemented without major operational issues and has contributed to general deterrence among aware riders.

Key finding

The impoundment law resulted in a significant 21.9% reduction in the proportion of motorcycle crashes involving unendorsed riders, despite no significant changes in overall endorsement rates or total crash numbers.

Methodology

mixed_methods

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• motorcyclist skill