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 way-finding crashes, particularly among older drivers. Intersections account for a significant portion of fatal and non-fatal crashes, with signalized intersections representing over half of all intersection-related incidents. While guidelines recommend these signs to provide drivers with additional time for lane changes and route selection, rigorous empirical evidence regarding their safety impact was previously lacking. The Federal Highway Administration (FHWA) conducted this evaluation as part of a pooled fund study involving 26 states, aiming to quantify crash reductions and determine the economic feasibility of the treatment. The research utilized an observational before-after study design with Empirical Bayes (EB) methods to estimate safety effectiveness. Data were collected from Arizona, Massachusetts, and Wisconsin, comprising 993 site-years in the before period and 829 site-years in the after period. Safety performance functions were calibrated for each state using generalized linear modeling with a negative binomial error distribution. The analysis examined total intersection-related crashes within 750 feet of the intersection, as well as specific crash types: injury, sideswipe, rear-end, and crashes involving drivers aged 65 and older. Reference intersections with similar characteristics but without the signs were used for comparison. Aggregate results indicated that advance street name signs had a minimal and statistically insignificant effect on total, injury, older driver, and rear-end crashes. However, the strategy yielded a significant 10.3% reduction in sideswipe crashes across all three states combined at the 90-percent confidence level. Massachusetts specifically showed a 27.2% reduction in sideswipe crashes. Disaggregate analysis revealed that the signs were more effective at three-legged intersections (on the major road), locations with high average annual daily traffic (AADT), and sites with two or more signs per approach. Economic analysis determined that the low annual cost per intersection ($172–$280) requires only a modest crash reduction to achieve a 2:1 benefit-cost ratio, making the strategy economically viable despite limited overall safety impacts. The study concludes that advance street name signs do not significantly reduce total crashes at signalized intersections and should not be implemented solely for general crash reduction. However, they are justified as a way-finding improvement, particularly for reducing sideswipe crashes. The findings suggest prioritizing installations at three-legged intersections, high-traffic locations, and sites with higher expected crash frequencies. The research provides states with evidence-based guidance for selecting low-cost safety improvements, highlighting that while the strategy has limited aggregate safety benefits, it offers targeted effectiveness for specific crash types and intersection geometries.
Key finding
Advance street name signs resulted in a statistically significant 10.3 percent reduction in sideswipe crashes at signalized intersections while having no significant effect on total, injury, older driver, or rear-end crashes.
Methodology
field_study
Sample size: 1822
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 | — | — | 24 | 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
- roadway lighting effects
- adas effectiveness
- incidence prevalence
- regulatory evaluation
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: crash risk outcomes