Impact of Access Management on Driver Behaviors
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Summary
This study investigates how drivers react to specific roadway designs and access management techniques, with a primary focus on circular intersections (roundabouts and traffic calming circles). Motivated by the need to quantify the impact of these designs on driving behaviors using naturalistic data, the researchers aimed to identify factors that predict driver hesitation or uncertainty. The project was conducted by the John A. Volpe National Transportation Systems Center for the National Highway Traffic Safety Administration (NHTSA) and the Governors Highway Safety Association. The analysis utilized data from the Second Strategic Highway Research Program’s Naturalistic Driving Study (SHRP2-NDS), which includes video feeds and vehicle sensor data. The team analyzed a stratified sample of 6,209 trips through 40 circular intersections across five states. Analysts at the Virginia Tech Transportation Institute coded video segments to identify instances of "unnecessary hesitation or uncertainty," defined as inappropriate maneuvers such as sudden braking, indecisiveness regarding entry/exit, or lack of acceleration. The study employed mixed-model logistic regression and Random Forest machine learning to determine predictors of these behaviors, examining variables including driver demographics, intersection characteristics, and contextual factors like secondary task engagement. The results indicate that driver hesitation and uncertainty occur most frequently during the entry phase of a circular intersection, with odds 2.64 times higher than during exit and 2.28 times higher than during traversal. Driver age emerged as the strongest predictor of these behaviors, showing a nearly linear increase in likelihood with age; specifically, drivers aged 45–49 exhibited significantly higher rates of hesitation compared to those aged 40–44. Engagement in secondary tasks, such as eating or using a cell phone, was the second strongest predictor, increasing the likelihood of hesitation by 9.1 percentage points. Additionally, intersections with two entry lanes resulted in a 1.38 times higher odds of uncertainty compared to single-lane entries. Other factors, such as roundabout diameter and household size, had smaller effects. The findings suggest that driver hesitation in circular intersections is primarily driven by driver-specific factors rather than geometric design alone. The strong correlation between age, distraction, and hesitation implies that educational or informational materials targeting these specific behaviors could mitigate uncertainty and improve traffic safety. By identifying that entry is the most challenging phase and that older or distracted drivers are most susceptible to hesitation, the study provides evidence-based insights for developing targeted countermeasures to enhance the safety and efficiency of circular intersections.
Key finding
Driver age and engagement in secondary tasks are the primary predictors of hesitation and uncertainty when navigating circular intersections, with older drivers and distracted drivers showing significantly higher rates of these behaviors.
Methodology
naturalistic
Sample size: 6209
Provenance
The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via bulk_ingest_rosap on 2026-05-23 (6 acquisition events logged).
| Stage | Outcome | Tool | Model | Prompt | Attempts | Completed |
|---|---|---|---|---|---|---|
| discover | success | rosap | — | — | 2 | 2026-05-23 |
| archive | success | — | — | — | 1 | 2026-05-23 |
| extract | success | cached | — | — | 2 | 2026-06-10 |
| clean | success | — | — | — | 1 | 2026-06-01 |
| chunk | success | — | — | — | 1 | 2026-06-01 |
| embed | success | — | — | — | 1 | 2026-06-02 |
| enrich | success | — | — | — | 1 | 2026-05-23 |
| promote | success | — | — | — | 1 | 2026-05-23 |
| summarize | success | llm | qwen3.6-27b-prismaquant | summ-v5 | 3 | 2026-06-10 |
| tag | success | vector_similarity | — | — | 19 | 2026-06-11 |
| verify | success | — | — | — | 2 | 2026-06-10 |
Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.
Topics
Ranked by relevance to this paper. Hover a topic for its definition.
- rail grade crossings
- perceptual countermeasures
- intersection design
- traffic density
- work zones
- driver vru interaction
Information type
What kind of knowledge this paper contributes, grouped by family — independent of topic (what it is about) and method (how it was studied).
- Empirical Findings: observational prevalence, behavioral performance data
- Methodological Resource: dataset resource