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Assessing crash propensity in work zone queueing events
Maria X Rojas1, Jonathan S Wood1, Skylar Knickerbocker1
1Institute for Transportation, Iowa State University, Research Park 4, 2711 S Loop Dr #4700, Ames, IA 50010, United States.
Accident; Analysis and Prevention
|July 21, 2026
Summary
Work zone crashes increase during slow or stop queues. Stop events double crash risk, while prolonged slow events over 27 minutes heighten risk, especially on high-speed roads.
Area of Science:
- Transportation Engineering
- Traffic Safety Research
- Road Infrastructure Management
Background:
- Work zones reduce roadway capacity, leading to congestion and safety issues.
- Understanding crash risks in work zones is crucial for effective lane-closure planning.
Purpose of the Study:
- To evaluate crash propensity during slow and stop queuing events in work zones compared to free-flow conditions.
- To inform safety integration into work zone lane-closure planning.
Main Methods:
- Analysis of Iowa's Traffic Critical Projects data, including traffic sensor and crash data.
- Classification of slow and stop queuing events using occupancy and speed thresholds.
- Development of a binary logistic regression model to predict crash occurrence.
Main Results:
- Work zones on high-speed roads, longer work zones, and afternoon events correlate with higher crash risk.
- Stop queuing events showed nearly double the crash risk of free-flow conditions.
- Slow queuing events exceeding 27 minutes significantly increased crash likelihood.
Conclusions:
- Crash propensity in work zones is influenced by roadway, work zone, and queuing characteristics.
- Integrating safety metrics into mobility-based lane closure planning is supported.
- Proactive safety management in work zones can be enhanced through these findings.
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