Mechanism of Early-Onset Breakdown at On-Ramp Bottlenecks on Shanghai, China, Expressways
Bibliographic record
Abstract
The mechanism of early-onset breakdowns was studied at on-ramp bottlenecks on expressways in Shanghai, China. From four on-ramp breakdown events captured on video, key parameters were extracted: prequeue flow, queue-discharge flow, speed variation per minute, lane change (LC) times in the mainline lanes and the acceleration lane, LC types, and LC locations (longitudinal and lateral). A total of 1,583 LC samples were analyzed. The findings showed a great difference in LC patterns when breakdowns occurred earlier than normal (i.e., before the bottleneck reaches expected capacity). In the case of an early breakdown, most LCs were forced LCs that occurred near the downstream end of the bottleneck, which spread laterally rather quickly. In contrast, in normal breakdowns in the United States, LCs were mostly free LCs that occurred evenly along the bottleneck longitudinally but were concentrated in rightmost lanes laterally.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.002 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".