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Comparative Study
. 2014 Nov 15;10(11):1169-77.
doi: 10.5664/jcsm.4192.

Adolescent crash rates and school start times in two central Virginia counties, 2009-2011: a follow-up study to a southeastern Virginia study, 2007-2008

Robert Daniel Vorona  1 , Mariana Szklo-Coxe  2 , Rajan Lamichhane  3 , J Catesby Ware  1 , Ann McNallen  4 , David Leszczyszyn  5
Affiliations
Comparative Study

Adolescent crash rates and school start times in two central Virginia counties, 2009-2011: a follow-up study to a southeastern Virginia study, 2007-2008

Robert Daniel Vorona et al. J Clin Sleep Med. .

Abstract

Background and objective: Early high school start times (EHSST) may lead to sleep loss in adolescents ("teens"), thus resulting in higher crash rates. (Vorona et al., 2011). In this study, we examined two other adjacent Virginia counties for the two years subsequent to the above-mentioned study. We again hypothesized that teens from jurisdictions with EHSST (versus later) experience higher crash rates.

Methods: Virginia Department of Motor Vehicles supplied de-identified aggregate data on weekday crashes and time-of-day for 16-18 year old (teen) and adult drivers for school years 2009-2010 and 2010-2011 in Henrico and Chesterfield Counties. Teen crash rates for counties with early versus later school start-times were compared using two-sample Z-tests and these compared to adult crash rates using pair-wise tests.

Results: Henrico teens manifested a statistically higher crash rate of 48.8/1000 licensed drivers versus Chesterfield's 37.9/1000 (p = 0.04) for 2009-2010. For 2010-2011, HC 16-17 year old teens demonstrated a statistically significant higher crash rate (53.2/1000 versus 42.0/1000), while for 16-18 teens a similar trend was found, albeit nonsignificant (p = 0.09). Crash peaks occurred 1 hour earlier in the morning and 2 hours earlier in the afternoon in Chesterfield, consistent with commute times. Post hoc analyses found significantly more run-off road crashes to the right (potentially sleep-related) in Chesterfield teens. Adult crash rates and traffic congestion did not differ between counties.

Conclusions: Higher teen crash rates occurred in jurisdictions with EHSST, as in our prior study. This study contributes to and extends existing data on preventable teen crashes and high school start times.

Keywords: crash rates; high school; start times; teens.

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Figures

Figure 1
Figure 1. Weekday crash rate of 16 to 18-year age groups in Chesterfield County and Henrico County for School Year 2009– 2010 (Sept. 2009–May 2010).
Figure 2
Figure 2. Weekday crash rate of 16 to 18-year age groups in Chesterfield County and Henrico County for School Year 2010– 2011 (Sept. 2010–May 2011).
See this image and copyright information in PMC

Comment in

  • High school start times and death on the road.
    Hamiduzzaman S, Phillips B. Hamiduzzaman S, et al. J Clin Sleep Med. 2014 Nov 15;10(11):1179-80. doi: 10.5664/jcsm.4194. J Clin Sleep Med. 2014. PMID: 25325585 Free PMC article. No abstract available.

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