Every full street wants to be a bus. In 1915 there were around 62,000 jitneys in 175 US cities: private cars giving nickel rides along the busiest streets. Where enough rides piled up on one corridor, they became fixed routes, then buses, and one of them became Greyhound. Mexico City's Metrobús replaced 372 microbuses with 212 articulated buses on one avenue. Hong Kong licensed its minibuses into "green" fixed routes. Uber Pool rediscovered the same thing and then gave up.
That is the game: rides between homes and jobs stack up on the same streets. When a corridor stays busy, you get an offer to turn it into a shared van. Fill the van and it becomes a bus, then a BRT lane, then a tram, then a metro. Each step carries more people in less road space, so cars stop jamming and the neighbourhoods grow.
Why it matters. A car lane moves 600 to 1,600 people an hour; a bus lane 4,000 to 8,000; a metro 60,000+. Ride-hail adds about 2.8 miles of driving for every mile of private driving it replaces, and about 40% of its miles are empty "ghost" cars (the grey ones). Households in car-dependent places spend over a quarter of income on transport, against about 8% in transit-rich ones. The jobs you can reach in 30 minutes, not raw speed, is what makes a place flourish.
Numbers come from the National Transit Database, NACTO, ITDP, Jarrett Walker's Human Transit, Schaller Consulting, CNT's H+T index and others. The research brief with sources is in the repository.
Walking and biking. A block within a quarter mile of a stop uses it on foot, so a line serves its neighbours too. Short trips are simply walked. A bike dock lets a block ride to stops up to three times farther away and bike dock-to-dock. The three incentives (crosswalks, bike lanes, open streets) make walking and biking feel shorter and reach farther, for the price of paint and a few bollards. Nothing frees road space more cheaply.
How to play. Tap a block to open its card and build a bike dock there. Tap an offer to accept it. Drag from a stop (white square) to another block to extend that line, or drag between two unserved blocks to start a van line yourself. Lines are capped at 8 and 8 stops each, so extend and upgrade rather than sprawl. Hover or tap a block to see its access score. Keyboard: space pauses, 1/2/3 set speed, M mutes. The seed in the URL recreates the same city.