Risk-Based Model for Identifying Highway-Rail Grade Crossing Blackspots
Bibliographic record
Abstract
A risk-based model is presented for identifying highway-rail grade crossing blackspots. This model consists of two prediction components: collision frequency and collision consequence. A graphic approach is adopted to identify crossings with unacceptable risks (high expected frequencies or consequences or both). These crossings are referred to as blackspots. The model was applied to Canadian inventory and collision occurrence data for the period 1997-2001. Poisson and negative binomial (NB) frequency prediction expressions were developed for crossings with three types of warning devices (signs, flashing lights, and gates). The NB model was found to provide a better fit to the collision frequency data. A weighted consequence score was introduced to represent combined collision severity. The weights used in this combined consequence score were obtained from insurance claims. An NB expression was developed for the collision consequence model. The spatial distribution of blackspots is discussed with respect to the type of warning device, upgrades in warning device, geographic location, and historical collision occurrence. A geographic information system platform was developed for the Ontario region and used to illustrate the spatial pattern of expected and historical collision frequency and associated blackspots.
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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 | 0.002 | 0.005 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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".