Interurban / 54 metros / San Francisco Bay
San Francisco Bay
A bay, a peninsula and hills, with the highest transit mode share outside New York. Every crossing is a chokepoint you pay for.
- Residents
- 4,486,687Census 2020, observed
- Census tracts
- 1,034TIGERweb, 2020 vintage
- Counties
- San Francisco, Alameda, San Mateo, Contra CostaWhat the pack covers
- Existing rail
- 12 lines, 230 stopsAgency GTFS
- Difficulty
- ForgivingPacific
What you are given
Every one of San Francisco Bay's 1,034 census tracts arrives with its real numbers attached: resident population, population 18 and over, occupied households, jobs by sector at the workplace, resident workers, and median household income — each one hoverable, each one carrying its GEOID so you can go and check it against the Census yourself.
Work trips are not guessed. They are seeded from the observed LEHD LODES home-to-work flows between those tracts, so the real spatial structure of the region — a century of geography, zoning and history that no gravity model reproduces — is preserved, and the model predicts only the change your network causes.
San Francisco Bay's existing network — 12 lines, 230 stops — is drawn from the operator's own published GTFS feed, in the agency's own line colours, with real opening years, so a game that starts in 1960 shows the 1960 network rather than today's.
What makes San Francisco Bay hard
Forgiving. Dense, centred, and already used to transit — the model has something to work with on day one. You are inheriting a system, which means you inherit its shape and its operating cost as well as its riders.
And the decade changes the problem, not the vehicle list. San Francisco Bay in 1960 is a different city from San Francisco Bay in 2025: smaller, denser, fewer cars per household, no federal transit money at all, and an expectation that you cover your own operating cost. The population distribution is back-cast by pivoting the real 2020 distribution rather than invented, so the rivers and the rail yards and the university stay where they are.
San Francisco Bay is in the free game. One of thirteen metros you can play without paying anything — the whole demand model, the operating budget, the events, the strike, the land use and the full progression ladder, on rail, in 2025, for ten years. Not a cut-down demo: the same simulation.
Where these numbers come from
- Population, households, population 18+ — Census 2020 PL94-171, tables P1, P3 and H1. Observed.
- Median household income — ACS 2018–2022 5-year, table B19013. Where the Census suppresses a tract, the pack records it as unknown and never estimates one.
- Jobs and commute flows — LEHD LODES8 2022, WAC, RAC and OD (JT00, S000). Observed.
- Tract geometry, water, roads — Census TIGERweb, 2020 tract vintage.
- Traffic counts — FHWA HPMS, functional class 1–4, as reported by the state DOT; each pack's own source string names the vintage its state publishes.
- Transit lines, stations and colours — the operating agency's published GTFS feed.
The full model specification, with every coefficient and its source →