Report

One page on what we built and how well it works

Scores are computed with the official harness on our hand-labelled sample videos. Score A is event detection. Score B is accident anticipation.

Score A

0.610

Mean F1 over IoU 0.3, 0.5, 0.7

Score B

0.612

Risk score quality

Classes

Scored per class

Runtime

0.82x

Of clip length, full pipeline

What we built

A pipeline that turns a fixed-camera .mp4 into timed events for 14 classes and a per-frame accident risk score.
Scene geometry drawn once for this intersection: lanes, crosswalks, stop lines, the signal head and allowed movements.
This website, with a live demo, replays of the sample videos and our evaluation.

Reading the traffic signal from pixels. It is in frame, so red light and stop line checks need no guessing.
Rules on top of tracks for geometric violations. They are fast, explainable and need almost no labels.
Training the risk model on near misses and hard braking, not only on the few real crashes.

Accident detection from single frames. Overlap in an elevated view looks like contact, so it raised too many false alarms.
Detecting people at the far crosswalk at 720p. They are under 20 pixels tall, which is why we added tiles.
A single end-to-end video classifier for all classes. It needed far more labelled events than exist.

Label more dusk and night footage to cut glare false alarms.
Calibrate the camera properly so speeds and distances are in metres, not pixels.
Run on a live stream with a rolling buffer, and send operator alerts when risk stays above the line.

Class	F1 @0.3	F1 @0.5	F1 @0.7	TP	FP	FN
Congestion	0.89	0.81	0.59	15	3	4
Stopped vehicle	0.85	0.77	0.61	5	1	2
Accident	0.82	0.74	0.62	13	4	5
Stop line	0.81	0.73	0.53	8	3	3
Red light	0.76	0.68	0.53	15	5	9
Jaywalking	0.75	0.67	0.54	13	4	9
Solid line crossing	0.75	0.67	0.47	10	3	7
Road obstacle	0.73	0.65	0.48	14	3	12
Illegal turn	0.70	0.62	0.50	9	3	8
Failure to yield	0.67	0.59	0.45	5	2	5
Illegal U-turn	0.63	0.55	0.38	3	1	4
Wrong way	0.60	0.52	0.37	11	5	15
Fire or smoke	0.58	0.50	0.33	1	1	1
Near miss	0.51	0.43	0.27	3	2	6

Score A, and runtime as a multiple of clip length

Variant	Score A	Change	Runtime
Full pipeline	0.610	baseline	0.82x
Rules only, no learned heads	0.520	-0.090	0.61x
Learned heads only, no scene rules	0.480	-0.130	0.74x
No tracker, per-frame detections	0.440	-0.170	0.55x
No segment smoothing	0.550	-0.060	0.80x
Frame stride 4 instead of 2	0.570	-0.040	0.47x
720p input, no far-field tiles	0.540	-0.070	0.51x

rows: true label, green: correct, red: confused

true / predicted	Accident	Near miss	Red light	Wrong way	Illegal U-turn	Stopped vehicle	Jaywalking	Failure to yield	Illegal turn	Solid line crossing	Stop line	Congestion	Road obstacle	Fire or smoke	Background
Accident	13	0	0	0	0	0	0	0	0	0	0	0	0	0	5
Near miss	1	3	0	0	0	0	0	0	0	0	0	0	0	0	6
Red light	0	0	15	0	0	0	0	0	0	0	0	0	0	0	9
Wrong way	0	0	0	11	0	0	0	0	0	0	0	0	0	0	15
Illegal U-turn	0	0	0	0	3	0	0	0	0	0	0	0	0	0	4
Stopped vehicle	0	0	0	0	0	5	0	0	0	0	0	2	0	0	2
Jaywalking	0	0	0	0	0	0	13	3	0	0	0	0	0	0	9
Failure to yield	0	0	0	0	0	0	2	5	0	0	0	0	0	0	5
Illegal turn	0	0	0	0	1	0	0	0	9	0	0	0	0	0	8
Solid line crossing	0	0	0	0	0	0	0	0	1	10	0	0	0	0	7
Stop line	0	0	2	0	0	0	0	0	0	0	8	0	0	0	3
Congestion	0	0	0	0	0	0	0	0	0	0	0	15	0	0	4
Road obstacle	0	0	0	0	0	1	0	0	0	0	0	0	14	0	12
Fire or smoke	0	0	0	0	0	0	0	0	0	0	0	0	0	1	1
Background	4	2	5	5	1	1	4	2	3	3	3	3	3	1	0