Runs with stopped-car contact · 24 selected simulations · October 2026 preprint
13 contacts → 0
Always-on guidance with perfect obstacle information. Simulations, not real-world accident rates.
Recognizing a stopped car is not the same as generating a path that stops before it. The same driving model made contact in 13 of 24 selected simulations without added braking guidance, and in none with an always-on stopping constraint and exact knowledge of the obstacle’s geometry.
The intervention changed how the model generated a path, not its training or camera. It shows what a constraint can achieve under ideal obstacle information, not that a car is ready to drive more safely on public roads.
More Detail, Sources and Data
Same Model, Same Selected Scenes
The researchers selected 24 braking-required scenes from 38 dynamic scenarios. These were simulated reconstructions of recorded drives using the frozen Alpamayo-1.5 model. The added guidance was always on and used privileged information: the obstacle’s exact geometry. It was not a test of an imperfect obstacle detector or of deciding when braking guidance should activate.
| Configuration | Runs with contact | Runs tested |
|---|---|---|
| Without added braking guidance | 13 | 24 |
| Always-on guidance, exact obstacle geometry | 0 | 24 |
The bars use one zero-to-24 scale. The first bar occupies 13 ÷ 24, or 54.17%, of the track; the zero bar has zero length. These are reported test outcomes, not estimated real-world crash probabilities. No simulator was rerun by Vastkind.
A Constraint Is Not the Whole Driving System
The useful result is narrower than a safer self-driving car: under ideal obstacle information, the model could obey a stopping constraint that it otherwise failed to enforce. Obtaining reliable obstacle information and deciding when to activate that constraint remain separate problems.
Source, Version and Reuse
Cercola et al., Perceives but Doesn’t Brake, arXiv:2610.28184v1, submitted October 20, 2026, Table I and the explicit 13-of-24 comparison. This is a preprint, not a peer-reviewed road-safety validation. Vastkind’s original visualization uses the paper’s reported counts under CC BY 4.0; it does not reproduce the authors’ graphic or JavaScript. Other experiments in the paper have different conditions and are not mixed into this comparison.