Comparison of Simulated Freeway Safety Performance with Observed Crashes
Bibliographic record
Abstract
This paper provides a link between simulated measures of safety performance and observed crash occurrence. Safety performance is expressed by using a crash potential index (CPI), established as a function of individual vehicle deceleration rates required to avoid a crash and of braking capabilities. Safety performance is compared with a sample of crashes observed on an instrumented segment of freeway. Three test results are reported: ( a) comparing safety performance in 1-min increments for a period 5 min before the precise crash time, ( b) comparing safety performance in 1-min increments over 5 min for matching crash and noncrash cases, and ( c) comparing average safety performance with observed crash rates for a 1-h period at the same site. The results of this study confirm that crashes tend to occur when measures of safety performance at a given site are higher than normal and that this measure increases with the approaching time to crash. The results provide basic evidence that the CPI measure of safety performance tends to reflect or explain increased crash risk subject to real-time changes in traffic conditions.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.008 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".