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What this is and is not a port of

Last edited by David Bloomin · ·

What this is and is not a port of

This coworld implements the control problem the SUMO-RL (Alegre) / CityFlow / RESCO benchmarks pose. It does not port them, and it does not claim comparability with them. Every divergence is named here.

1. No SUMO, no CityFlow, no port

Decided as a scoping rail before design. SUMO is a C++ desktop simulator with XML networks, its own RNG and its own car-following model; embedding it would mean a pod-side simulator that cannot compile to WebAssembly, so the static replay viewer — a non-optional platform pin — would be impossible.

No upstream code is vendored, no upstream numbers are cited as reproduced, and no benchmark score from this coworld is comparable to any published result. What is reproduced is the SHAPE of the problem: per-seat intersection signal control, queue and waiting-time pressure, cooperative network-throughput scoring, and green waves as an emergent phenomenon.

2. Vehicles are cellular, not car-following

One car per cell, one cell per tick, no acceleration, no headway model, no lane changing, one lane per approach. This is the CityFlow-style discrete idiom rather than SUMO's continuous Krauss model, and it is what makes the native ↔ wasm hash chain exact: the sim is integer-only end to end, so the game server and the browser viewer re-derive the identical tick.

3. No start-up lost time and no yellow-interval discharge

Clearance is a flat 2 ticks of all-red. A queue steps forward the same tick its head discharges, because the link advance iterates downstream-first. A real signal loses one to two seconds of saturation flow at the start of every green; this one does not.

4. The reward shape is a league score, not a per-intersection reward

SUMO-RL's per-intersection reward is −queue or −waiting. The league needs ONE rankable per-seat integer, so:

  • network throughput is the dominant term (1 000 000 a car),
  • network waiting is second (1 000 per 200 wait-ticks),
  • the seat's own waiting is third and deliberately an epsilon (10 per 800 wait-ticks).

All three underlying quantities are recorded in results (throughput, networkWaitTicks, seatWaitTicks), so the SUMO-RL-style local signal is still readable per seat.

5. One network: the 4 × 4 grid

Cologne, Ingolstadt and Manhattan are out of scope. They are OSM imports whose geometry cannot be re-derived in the viewer from a variant name, whose intersections have five and six approaches that the reply schema does not express, and none of which is legible in a 360 px featured-match iframe.

6. Who chooses the phase changed, not what the phases are

Per-tick RL policies are replaced by four turn-level ORDERS under a deterministic per-tick actuator — the source idea's own "phase choice every 5–10 s … suits LLM policies well". The four-phase NEMA-style plan, the minimum green, the all-red clearance, the maximum red and the single-lane approaches are the benchmark idiom, unchanged.

7. One game per episode

The starter's multi-game episode is not used: a cooperative game has no side to swap.

8. Seat count and intersection count are fixed

num_agents is 4 in every variant and in the certification fixture, and the city has 16 intersections. The source idea's "4–48 intersections" is answered at 16, inside the range. More seats is a wall-clock and sidecar-rate problem, not a design one: four calls a turn at a 12 s batch floor is 20 requests a minute against a 30/minute per-episode cap, and sixteen seats would be 80.

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