Motion Prediction Methods for Surrogate Safety Analysis
Bibliographic record
Abstract
Despite the rise in interest in surrogate safety analysis, little work has been done to understand and test the impact of methods for motion prediction, which are needed to identify whether two road users are on a collision course, and to compute several surrogate safety indicators such as the time to collision. The default, unjustified method used in much of the literature is prediction at constant velocity. In this study, a generic framework is presented to predict road users' future positions depending on their current position and their choice of acceleration and direction. This method results in the possibility of generating many predicted trajectories by sampling distributions of acceleration and direction. Three safety indicators—the time to collision, an extended version of predicted post encroachment time, and a new indicator measuring the probability that the road user's attempted evasive actions will fail to avoid the collision—are computed over all predicted trajectories. These methods and indicators are illustrated in four case studies of lateral road user interactions. The evidence suggests that the prediction method based on the use of a set of initial positions seems to be the most robust. Another contribution of this study is to make all the data and code used available (the code as open source) to enable reproducibility and to start a collaborative effort to compare and improve the methods for surrogate safety analysis.
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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 | 0.003 | 0.017 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 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".