What would it take to improve public transportation in New York so that all or nearly all routes would run at worst even six minutes during midday? Today, frequencies are tailored to individual routes; a bunch of subway lines are a 10-minute city (and the A branches are a 15-minute city), and in Brooklyn, the median midday bus headway is 12 minutes, with wide variations.
The bus origin of six minutes
Six minutes is not an arbitrary number. It comes from Eric’s and my Brooklyn bus redesign; speeding up routes through stop consolidation, dedicated lanes, and off-board fare collection, and pruning and recombining some routes, lets every bus run every six minutes from 6 am to 10 pm all day every day, with higher frequency on those routes that already have it today because they are too busy for just ten buses per hour. We didn’t study the other boroughs as deeply, but a quick doodle suggested the six-minute standard could be met in Manhattan and the Bronx as well, and a Bronx bus grid could even dip into a five-minute city.
Queens is a wildcard and I’m going to disappoint readers by not talking about it. It is clearly possible given the operational treatment we propose to make most of Queens a six-minute city, but at the price of long route spacing in Eastern Queens, and I don’t know what is optimal. It’s a hard question and I’m not going to tackle it unless I’m actually working on a longer-term project to do a Queens bus redesign.
Six minutes on the subway
The subway right now is a 10-minute city. A lettered or numbered route runs every 10 minutes off-peak, sometimes every 12 on Sundays and at night; the busier routes, especially the four that do not share tracks with other routes (1, 6, 7, L), run more frequently, but 10 minutes is the base frequency on large swaths of the network. The A branches in Ozone Park and the Rockaways even run every 15 minutes, but that’s unusual enough – evidently, nowhere else does one letter or number denote a route with its own branches – that it can be excluded.
For comparison, Berlin’s rail network is a 10-minute city, with some outer S-Bahn branches running every 20 minutes. Within the Ring, Berlin is a 5-minute city for the most part, excluding just a two-hour midday dip to 10 minutes on the Ring and 10-minute frequencies on the U1/U3 branches and the practically useless U4 route. Paris makes no effort to run different routes at the same intervals – French rapid transit planning has self-contained lines with their own fleets and schedules, so for example the RER A is on 10-minute off-peak takts and the RER B on 15-minute ones. So frequency there greatly depends on where in the region one lives and on what line. The Métro is a 5-minute city for the most part, as are the intramural RER trunks; intramural buses can be ignored. The suburbs are more or less a 15-minute city.
The reason New York is a 10-minute city on the subway is partly about interlining. The trunks in theory run every 5 minutes or better, but the trains do not come evenly because sometimes trains with different frequencies share the same trunk, and delays propagate easily. Interlining really doesn’t work unless all trains come at the same frequency; this is familiar in German planning, but not in American planning (or French planning, but there’s barely any interlining in Paris).
Putting every subway route on a 10-minute takt, with double service on the four non-interlined services, is possible but would lead to a lot of crowding on the busiest lines. About the worst possible frequency that works for everything is a train every 7.5 minutes; this lets the two A branches run on 15-minute takts, and everything else run on a 7.5-minute takt. But even then, New York has so many missed connections that it’s useful to do better. The six-minute city, matching buses, turns most of Manhattan and inner Brooklyn and Queens into a three-minute city.
Running all trains on the same takt also means timed connections. Trains that run every 5 or 6 minutes can routinely be timetabled to be at predictable places at predictable times, which facilitates local/express transfers on branches, for example in Southern Brooklyn. Even trunk transfers can be timed – 3-minute trains can still run on a timetable, and the most valuable transfers are local/express ones at 96th/Broadway, 125th/St. Nicholas, and 125th/Lex, all far enough north so as to not have the huge tidal crowds of Times Square or Grand Central.
What would it take?
On the buses, just good redesign, as long as the city is willing to exclude Staten Island from the six-minute city. In Queens, some increase in bus service is probably warranted.
On the subway, this requires on the order of 110-120 million revenue train-km a year, which is 1 billion car-km. The current figure is 560 million car-km/year. There is a lot of unnecessary expenditure on the subway, but fixing that requires something a lot deeper than a bus redesign. The cut in operating costs would be to levels that are well within first-world levels, and some of it would just come from better off-peak service making crew scheduling easier, without split shifts or wasted time. But it does require serious changes, especially in maintenance.