Game Systems/The Network

Modes and infrastructure

Four transit modes, unlocked by city population. They are not tiers of the same thing — each occupies a different point on the cost, speed, capacity and reach curve, and the right answer changes with the corridor.

The four modes#

	Bus	Tram	Metro	Commuter Rail
Unlocks at	0	50,000	150,000	300,000
Track $/m	150	9,000	45,000	14,000
Station	$8k	$120k	$4.5M	$1.8M
Vehicle	$90k	$1.6M	$3.2M	$5.2M
Capacity	60	200	900	1,400
Speed	8.3 m/s	11 m/s	19.5 m/s	27.7 m/s
Dwell	20s	25s	30s	45s
Min headway	120s	90s	90s	300s
Walk radius	450 m	600 m	800 m	1,000 m
Station spacing	300-500 m	400-800 m	800-1,500 m	1,500-4,000 m

Daily upkeep scales the same way — a metro costs $450/km/day against a bus's $12.

Reading the table#

Bus is nearly free to build and expensive to run relative to what it carries. Its 450 m walk radius is the smallest, so it needs dense stops to catch anyone.

Tram is the awkward middle: track costs 60× a bus's, and it carries 200. It earns its place on a corridor too busy for buses and too thin to justify a metro.

Metro is the capacity workhorse. 900 per vehicle at a 90-second minimum headway is an enormous corridor ceiling, and the 800 m walk radius means each station catches a wide area. It is also the most expensive thing you can build.

Commuter rail is the fastest and highest capacity, but its 300-second minimum headway and 45-second dwells make it wrong for short hops. Its 1,000 m walk radius and 1,500-4,000 m station spacing tell you what it is for: long trips from far out, not city-centre circulation.

Note that rail track is cheaper per metre than metro — the expense is in stations and vehicles. Long distances favour rail; dense stopping patterns favour metro.

Grade#

Track can run at surface, elevated, or in tunnel, and the cost multiplier depends on the mode:

Bus is surface only.
Tram — surface ×1, elevated ×2.6, tunnel ×7.
Metro — tunnel ×1, elevated ×0.65, surface ×0.4.
Rail — surface ×1, elevated ×2.4, tunnel ×6.

Metro is the exception worth internalising: its baseline is tunnel, so putting metro on the surface costs 40% of the tunnelled price. Where you have the right of way, surface metro is dramatically cheaper.

Water#

Crossing water multiplies track cost by 5. A bridge or tube is the single most expensive decision in a corridor, and routing around water is often worth a substantial detour.

Demolition#

Removing infrastructure refunds 25%. Mistakes are expensive but not fatal.

What this means in play#

Unlock order is a budget problem, not a tech tree. A metro becomes available at 150,000 people; affording one is a separate question.
Match walk radius to density. A bus's 450 m catchment in a sparse suburb reaches almost nobody. Rail's 1,000 m is what makes distant stations viable.
Surface metro is the value play. At ×0.4 it undercuts its own tunnel baseline by more than half.
Minimum headway is the real capacity ceiling. Rail carries 1,400 but cannot run more often than every 5 minutes; metro carries 900 every 90 seconds. Metro wins on corridor throughput despite the smaller vehicle.
Avoid water until you have to. ×5 on track cost.