Comparison of identification and ranking methodologies for speed-related crash locations.
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Summary
This study addresses the lack of a systematic methodology for prioritizing locations for speed-related safety countermeasures in Oregon. Speeding was identified as a primary causal factor in 27% of total crashes and 36% of fatal crashes on the Oregon state highway system between 2000 and 2002. Because resources for safety improvements are limited, the research aimed to develop and compare ranking methods to identify highway segments where countermeasures would have the greatest impact. The study also sought to refine existing network screening techniques by incorporating specific crash variables, such as ice and curves, which were found to be overrepresented in speed-related incidents. The researchers conducted a comprehensive analysis of crash data from 2000–2002, utilizing a literature review on speed-crash relationships and reduction techniques. They developed and compared four distinct network screening methods to rank crash locations: crash frequency, statewide crash rate, statewide Rate Quality Control (RQC), and a refined zonal RQC method. The zonal RQC method incorporated climate data to account for regional variations, allowing for the identification of road segments with statistically significant high speed/ice crash patterns. The study employed statistical tests, including the Wilcoxon Signed Rank Test, to compare the efficacy of these ranking methods. Additionally, a case study was conducted on the top 20 sites identified by the refined zonal RQC method to evaluate the feasibility of deploying specific countermeasures, such as automated ice warning systems, anti-icing systems, and pavement heating. The analysis revealed that variables such as ice, curves, and darkness were significantly overrepresented in speed-related crashes. The comparison of screening methods demonstrated that the zonal RQC method provided a more robust identification of high-risk locations than frequency or simple rate-based methods, as it accounted for local climate conditions and statistical significance. The case study of the top 20 identified sites confirmed the practical applicability of the refined screening technique, with specific countermeasures proposed for locations on routes including I-5, I-84, OR-35, OR-58, and US-26. The study concluded that integrating climate zones into the RQC method improves the accuracy of identifying locations prone to speed-related crashes, particularly those involving icy conditions. The significance of this research lies in providing the Oregon Department of Transportation with a documented, repeatable procedure for prioritizing safety investments. By establishing a more robust method for identifying highway locations based on crash type and contributing variables, the study supports more effective allocation of limited resources. The findings suggest that tailored countermeasures, such as ITS technologies and geometric modifications, can be more effectively deployed when guided by statistically sound ranking methodologies. This approach enhances the potential for reducing speed-related fatalities and injuries, offering a model that can be extended to other jurisdictions and crash types.
Key finding
The zonal Rate Quality Control method incorporating climate data effectively identified highway segments with statistically significant high speed/ice crash patterns, offering a superior prioritization tool compared to standard statewide ranking methods.
Methodology
dataset
Sample size: 60000
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 | partial | — | — | — | 2 | 2026-06-10 |
Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified_with_issues.
Topics
Ranked by relevance to this paper. Hover a topic for its definition.
- incidence prevalence
- roadway lighting effects
- naturalistic crash near crash
- perceptual countermeasures
- speed management
- rail grade crossings
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, observational prevalence
- Methodological Resource: dataset resource