Safety evaluation of advance street name signs
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Summary
This study evaluates the safety effectiveness of advance street name signs at signalized intersections, a low-cost strategy intended to reduce crashes involving older drivers and way-finding errors, such as rear-end and sideswipe collisions. Motivated by the need to rigorously assess experimental safety countermeasures identified in the NCHRP Report 500 Series, the Federal Highway Administration conducted this analysis as part of the Evaluation of Low-Cost Safety Improvements Pooled Fund Study. The research aimed to determine if providing drivers with earlier notice of cross streets significantly reduces crash frequency and severity, particularly for vulnerable populations like older drivers who require more time to process navigation information. The methodology employed an Empirical Bayes (EB) before-after analysis to account for selection bias and regression-to-the-mean. Data were collected from 193 signalized intersections across three states: 82 sites in Arizona, 65 in Massachusetts, and 46 in Wisconsin. The study utilized geometric, traffic, and crash data, comparing crash frequencies before and after the installation of green MUTCD D3 series advance guide signs. Safety performance functions were calibrated using reference sites to estimate expected crash counts, allowing for a rigorous assessment of safety changes across various crash types, including total, injury, rear-end, sideswipe, and older driver crashes. The aggregate analysis revealed that sideswipe crashes were the only crash type with a statistically significant reduction. Massachusetts experienced a 27% reduction in sideswipe crashes, while the combined three-state analysis showed a 10% reduction. In contrast, changes in total crashes were statistically insignificant: Massachusetts and Wisconsin showed slight reductions (3.0% and 3.7%, respectively), while Arizona showed a slight increase (3.4%). The combined total crash reduction was only 1.6%. Disaggregate analysis indicated that the signs were more effective on major roads at three-legged intersections, at locations with high average annual daily traffic (AADT), and at sites with a high expected number of crashes. Additionally, installing two or more signs per approach proved more effective than a single sign. The study concludes that while advance street name signs have a minimal effect on total crash frequency, they are effective at reducing sideswipe crashes and enhancing way-finding. Given the low implementation cost, the strategy achieves a 2:1 benefit-cost ratio with a reduction of just 0.01 crashes per intersection-year. Consequently, the use of advance street name signs is justified as a way-finding improvement, particularly at three-legged intersections and high-volume locations, though it is not recommended as a primary measure for reducing total intersection crashes.
Key finding
Advance street name signs significantly reduced sideswipe crashes by 10 percent across three states and 27 percent in Massachusetts, but produced no statistically significant change in total crash frequency.
Methodology
field_study
Sample size: 193
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
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- signage environment
- incidence prevalence
- roadway lighting effects
- regulatory evaluation
- adas effectiveness
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).
- Applied Guidance: countermeasure evaluation
- Empirical Findings: crash risk outcomes