# L4RA building clearance along traffic routes, r407

## Method

I loaded the packaged L4RA scene in host Chrome with ANGLE/Vulkan; the XP
guest GPU was not used. The browser built the road index from the complete
regional GLB and a facade collision index from all exported `XB_` surfaces.
I sampled the 832 recovered traffic routes every 2 m, applied the viewer's
source-texture lane hint, and retained only points supported by an authored
road triangle. That produced 86,285 road-supported route samples. At each
sample, the check used the viewer's 1.9 m player-center collision radius and
its `route Z +0.25..+1.75 m` facade-height band.

## Findings

The center-path pass reported one facade group, `XB_HARBORA_NEON_1A_LL_00`,
near the shared Harbor route section on route 415 at distances 670–678 m and
route 567 at 8–16 m. The host Chrome view shows the car on the marked freeway
with a close roadside wall; it does not show a building face crossing the
driving lane in this frame. This is a close-clearance warning for the viewer's
collision radius, not evidence that the source placement is wrong.

A separate conservative footprint pass also checked points 1.2 m to either
side of the route center. It additionally found `XB_WATERTREATMENT_1A_CK_00`
at route 1020 distance 0. The capture is an explicitly selected diagnostic
start, not the default L4RA spawn. Its industrial apron has street furniture
and a large structure close to the chase-camera view. This identifies a
cramped viewpoint that needs a separate placement/scene check; it does not
establish a misplaced building.

No city instances or route data were moved or removed. The scan covers sampled
traffic-route corridors in L4RA, not the whole city, unsampled gaps, non-`XB_`
props, or retail visibility state. The default L4RA start remains route 450.

- [Harbor route 415, distance 670](../webgl-city/review/images/548-r407-harbor-route-clearance.png)
- [Water-treatment route 1020 diagnostic start](../webgl-city/review/images/549-r407-water-treatment-clearance.png)
- [Scrollable visual review feed](../webgl-city/review/)