Effectiveness of countermeasures to reduce vehicle speeds in freeway work zones
Bibliographic record
Abstract
Slowing motorists within work zones on high-speed roadways continues to be a challenge for highway authorities in all jurisdictions. Many work area traffic control manuals (WATCM) limit the speed reduction on high speed facilities to not be more than 20 km/h on the premise that a larger reduction is not practically achievable. The result is that workers on high-speed facilities are often exposed to excessive vehicle speeds in live lanes adjacent to their work sites. This study identified and evaluated supplemental traffic control countermeasures that will achieve speed reductions beyond 20 km/h. The countermeasures tested included singularly and combinations of: floating speed zones (FSZ); traffic control person (TCP); narrow lanes; radar speed display board (RSDB); variable message sign (VMS); and a fake police vehicle. The top ranked countermeasures, TCP and FSZ, fake police vehicle and FSZ, and the RSDB and FSZ, resulted in mean speed reductions of 23 km/h, 19 km/h, and 19 km/h, respectively, and typically with significant reductions in speed dispersion.
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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 | 0.005 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".