Effects of work zone presence on injury and non-injury crashes

Asad J. Khattak, Aemal J. Khattak, Forrest M. Council

Research output: Contribution to journalArticlepeer-review

150 Scopus citations


Work zones in the United States have approximately 700 traffic-related fatalities, 24000 injury crashes, and 52000 non-injury crashes every year. Due to future highway reconstruction needs, work zones are likely to increase in number, duration, and length. This study focuses on analyzing the effect of work zone duration mainly due to its policy-sensitivity. To do so, we created a unique dataset of California freeway work zones that included crash data (crash frequency and injury severity), road inventory data (average daily traffic (ADT) and urban/rural character), and work zone related data (duration, length, and location). Then, we investigated crash rates and crash frequencies in the pre-work zone and during-work zone periods. For the freeway work zones investigated in this study, the total crash rate in the during-work zone period was 21.5% higher (0.79 crashes per million vehicle kilometer (MVKM)) than the pre-work zone period (0.65 crashes per MVKM). Compared with the pre-work zone period, the increase in non-injury and injury crash rates in the during-work zone period was 23.8% and 17.3%, respectively. Next, crash frequencies were investigated using negative binomial models, which showed that frequencies increased with increasing work zone duration, length, and average daily traffic. The important finding is that after controlling for various factors, longer work zone duration significantly increases both injury and non-injury crash frequencies. The implications of the study findings are discussed in the paper.

Original languageEnglish (US)
Pages (from-to)19-29
Number of pages11
JournalAccident Analysis and Prevention
Issue number1
StatePublished - Jan 2002


  • Crash rates
  • Injury severity
  • Negative binomial model
  • Work zones

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Safety, Risk, Reliability and Quality
  • Law
  • Human Factors and Ergonomics


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