# Japanese expressway road-standard reference (verified)

Compiled 2026-08-01 for the Tokyo Wangan Racing circuit. Every figure here was
read from a primary standard or an official sign artwork file, **not** from
recollection. Where a commonly-repeated number turned out to be wrong, that is
called out explicitly, because the wrong versions are widespread online.

## Road markings — 全標協 (Japan Road Marking Association) 2012 / 2018

| Element | Spec | Source |
|---|---|---|
| 車線境界線 lane boundary (dashed) | line length **3–10 m**; gap **1×–2× the line length**; width **10–15 cm** (15 cm "desirable") | 全標協 2012 p.42 |
| Lane boundary where overtaking undesirable (屈曲部/curves) | becomes **solid** instead of dashed | 全標協 2012 p.42 |
| Boundary vs 変速車線 (accel/decel lane at ramps) | length **2 m** (3 m on decel lanes), width **45 cm** | 全標協 2012 p.42 |
| 導流帯 gore / zebra hatching | **45 cm** white solid bars repeated every **1.0 m**; bounded by a 15–20 cm edge line | 全標協 2018 pp.97–98 |
| Zebra around an obstruction | 45 cm bars at 1.0 m, guided by arrows upstream | 全標協 2018 |
| Dashed extension of edge line through intersections | width 15–30 cm, line+gap every 0.5–2.0 m | 警察庁 2014 p.11 様式4 |

**Correction to a widely-repeated claim.** The "45 cm wide lines on expressways"
figure that circulates online is *not* the lane boundary — 全標協 2012 p.42 gives
45 cm only for the boundary between a through lane and a **変速車線**
(acceleration/deceleration lane). Applying 45 cm to ordinary lane dividers makes
the road look like it is all ramp. Lane dividers are 15 cm.

**On 8 m / 12 m.** The standard specifies a *range* (3–10 m line, gap 1–2×), not a
single value. 8 m line / 12 m gap sits inside that range at the high-speed end
(gap = 1.5× line) and is the configuration used at expressway speeds; a 5 m/5 m
rhythm reads as a surface street. Treat 8/12 as "a legal expressway
configuration", not as "the one legally mandated number".

## Colour values — sampled from official sign artwork, not estimated

| Use | Value |
|---|---|
| Guide sign (案内標識) green | **#005D35** |
| Shutoko route badge green | **#007F1F** |
| Sign lettering | white #FFFFFF |

Japanese **expressway** guide signs are green; ordinary-road guide signs are
blue. Shutoko uses green.

## Speed limits (from the route articles' own signage tables)

| Route | Posted |
|---|---|
| C1 都心環状線 (Inner Circular) | **50 km/h** mainline, **40 km/h** inside the junction sections — 江戸橋JCT内, 浜崎橋JCT内, and 京橋JCT–旧白魚橋乗継所 are each posted 40 in the route's own 車線・最高速度 table |
| B 湾岸線 (Bayshore/Wangan) | **80 km/h** (60–70 in places) |

The C1 and the Wangan are **not** the same limit — a C1-shaped circuit should be
posted 50, not 80.

## Caveats / not verified

- Lamp pole spacing (~35 m) and parapet heights are reasonable engineering
  values but were **not** confirmed against a primary source; they are tuned by
  eye for gameplay readability.
- Asphalt/concrete RGB values in MapBuilder are art direction, not measured
  photometry. Porous asphalt (排水性舗装) does read darker and coarser than
  ordinary asphalt, which the palette reflects.

## Structural sections of the C1 (drives MapBuilder geometry)

The C1 is not a uniform elevated tube — it changes structural type along its
length, and the circuit now renders each type differently.

| Section | Real-world form | In-game |
|---|---|---|
| Elevated viaduct (most of the loop) | Deck on concrete columns | `Pillar` every 3rd sample above Y=18 |
| Bridge spans (474 flagged samples) | Steel box girder 鋼箱桁橋 over the old canals | `BridgeGirder` + `GirderRib` under deck; `PierCap` + round `PierColumn` on a 6-sample pitch |
| Ginza 銀座 | Runs **below** street level in the filled-in 楓川・築地川 river beds; surviving city bridges cross **over** it, piers landing in the median | `GinzaOverpass` + `OverpassParapet`, `OverpassPier` in the median |
| Tunnel sections | Bored/cut-and-cover | Tunnel bore, ceiling, no sky lighting |

Girder depth is set from the span/depth rule of thumb for steel box girders
(≈1/20 of span): at ~35 m spans that is ~1.8 m ≈ 6.4 studs (`GIRDER_H`).

**Why Ginza bans lane changes.** The no-lane-change marking through Ginza is not
arbitrary styling — the crossing bridges' piers physically occupy the median
between the carriageways, so the lanes are separated by structure. The yellow
line and the `OverpassPier` geometry are two expressions of the same fact.

## Lane counts

| Section | Lanes |
|---|---|
| Most of C1 | 2 + 2 |
| Shiodome JCT → Hamazakibashi JCT | **3 + 3** (widened; carries the merge from the Haneda line) |

Rendered by `widthAt(i)`: 60 studs baseline, 82 studs in `WIDE_ZONES`, with a
taper between so the widening never steps more than ~1.7 studs per sample.

## Method note

Wikipedia article *extracts* (`prop=extracts`) silently drop the infobox and
table markup that carry these figures — the measurements only appear in the raw
wikitext (`prop=revisions&rvslots=main`). Query the wikitext when hunting for
specs.