# L4RA traffic routes against exported pavement, r406

## Full-stream support scan

The packaged viewer loaded the default L4RA scene and its complete road-surface
index, then sampled the 832 recovered L4RA traffic routes at 5 m intervals.
Each point used `trafficPoseOnRoadLane()` and was checked against the same
authored road triangles used for WebGL driving. The road index is built from
the selected region GLB's full scene mesh set, not just the current 240 m draw
radius.

| Result | Count |
| --- | ---: |
| Route definitions sampled | 832 |
| Route samples | 37,233 |
| Samples with road support | 34,757 (93.35%) |
| Samples without road support | 2,476 (6.65%) |
| Fully supported routes | 655 |
| Partially supported routes | 156 |
| Routes with no supported samples | 21 |

Examples with long unsupported spans include route 1018 (`TrackRoutesA43`, 7
of 83 samples supported), route 1017 (`TrackRoutesA42`, 40/110), and route
1029 (`TrackRoutesA43`, 0/73). This measures compatibility with the current
driveable-pavement index; it does not prove those route records are erroneous
or that a missing road should be added. No source instances or route points
were moved or deleted.

## Traffic preview change

The local traffic selector already required road support at its chosen spawn
sample. The decompiled lane driver uses a 15–30 m forward point queue; the
preview now also requires the selected spawn to have road support at 5 m
intervals through 30 m ahead. This prevents a car from starting on a short
supported patch with its immediate lookahead crossing an unsupported section.
Routes that lack a supported runway are rejected with an
`unsupported-lookahead` debug reason. This is a pavement-validity guard for the
WebGL preview, not a reconstruction of the retail actor's live route choice.

## Host Chrome visual check

The packaged viewer reached `City scene ready` at the default Route 450 start
with 223/223 nearby textures and no page or console errors. After a short W
hold, the screenshot shows the 240SX on the marked road and traffic ahead. The
debug output reported seven traffic assignments; rendered samples reported
road support and near-world-up frames. This does not establish retail traffic
behavior, full-route city correctness, or visual parity.

- [L4RA traffic runway capture](../webgl-city/review/images/547-r406-l4ra-traffic-runway.png)
- [Scrollable visual review feed](../webgl-city/review/)
- [Traffic runtime contract and missing live inputs](traffic-driver-runtime-contract-r347.md)