Four fidelity fixes, all verified in a live Studio datamodel (not just built):
1. Wire up the dead `bridge` flag. Circuit.luau marks 474 samples as bridge
spans but nothing ever read the field, so every elevated metre rendered as
the same slab on square columns. Flagged spans now get a steel box girder
(鋼箱桁橋) with stiffener ribs under the deck, carried on a transverse pier
cap and round columns at a wider pitch than the viaduct pillars.
2. Ginza 跨道橋. The Ginza section sits below street level in the filled-in
楓川・築地川 river beds and the surviving city bridges cross over it, their
piers landing in the median. Adds the crossing decks, parapets and centre
piers -- which is the physical reason lane changes are banned there, not
just a paint choice.
3. Junction speed plates. 江戸橋JCT内 / 浜崎橋JCT内 / 京橋JCT-旧白魚橋乗継所 are
posted 40 km/h, not the 50 km/h mainline limit; plates repeat more often
through the short restricted stretches.
4. Shiodome JCT -> Hamazakibashi JCT widened to 3+3 lanes via widthAt(), with
a taper (max ~1.7 studs/sample) instead of a step. Every fixed-width
consumer -- deck, median, parapets, lane marks, signage offsets, skyline
setback, finish line -- now reads widthAt() so nothing floats or clips.
Verified headlessly (tools/verify_c1_fixes*.luau):
girders 488 / 474 flagged samples, pier caps 85, columns 80
Ginza overpasses 7, piers 7, lateral offset from centreline 0.000 studs
speed plates 40km/h x7, 50km/h x8
deck width Shiodome 81.5 vs Kasumigaseki 60.0
seam lip max 0.0006, road-surface raycast step max 0.260, 0 deck holes
Two earlier "failures" were bad tests, not bad geometry, and the fixed
harnesses document the traps: deck parts are pitched by CFrame.lookAt so
Position.Y+Size.Y/2 is not the surface height (and LookVector is -Z, so the
end faces are easy to swap), and a seam raycast must filter to the Expressway
folder or it hits TunnelCeiling/MedianFence and reports a phantom 19-stud step.
