JSON feeds

Three pages on transitlab.nyc load their numbers from JSON files. You can load the same files. They are rebuilt every night, cached for five minutes, and small enough to fetch from a web page.

Feed	Size	Drives
/data/slow-zones.json	about 30 KB	Subway slow zones
/data/bus-speeds.json	about 60 KB	Bus speeds
/data/bus-lanes.json	about 1.7 MB	Bus lane map

All three start with updated, the date the file was built (YYYY-MM-DD). Field names may grow; we won’t rename or remove one without notice here.

const zones = await fetch("https://transitlab.nyc/data/slow-zones.json").then((r) => r.json())
console.log(zones.summary.active, "slow zones active")

slow-zones.json

Subway slow zones, the same numbers as the subway_slow_zones and subway_slow_zones_weekly tables, already summed up.

Field	Type	What it is
updated	date	When the file was built.
dataThrough	date	Last weekday of train data in it.
summary.active	number	Slow zones active in the last week of data.
summary.riderHoursPerWeekday	number	Rider-hours lost each weekday, averaged over the last four full weeks.
summary.trainHoursPerWeekday	number	The same in train-hours.
weekly[]	list	One entry per week since January 2022.
weekly[].week	date	Monday of the week. The first and last weeks are partial.
weekly[].riderHours	number	Rider-hours lost to slow zones that week.
weekly[].trainHours	number	Train-hours lost that week.
active[]	list	Up to 30 active zones, costliest first. Each is a zone, below.
biggest[]	list	The 25 costliest zones since 2022.

A zone has:

Field	Type	What it is
segment	string	Readable name, e.g. Queensboro Plaza → 60 St tunnel.
routes	string	Routes through it, space-separated, e.g. N W.
start, end	date	First and last slow weekday.
slowDays	number	Slow weekdays in the zone.
baselineS	number	Usual seconds for the segment.
extraS	number	Median extra seconds per train.
extraPct	number	extraS as a percentage of baselineS.
riders	number	Riders through the segment on a typical weekday.
riderHoursLost	number	Total rider-hours lost over the zone.
trainHoursLost	number	Total train-hours lost.

bus-speeds.json

Bus speeds from two sources: the MTA’s monthly figures (history, a month or so late) and our own daily speeds (recent days).

Field	Type	What it is
updated	date	When the file was built.
mtaThrough	month	Latest month the MTA has published (YYYY-MM).
oursThrough	date	Latest day of our own speeds.
periods.routes	list of months	The three months the route speeds cover.
periods.routesYearAgo	list of months	The same months a year before.
summary.citywideMph	number	Weekday citywide speed in mtaThrough.
summary.citywideYearAgo	number	The same month a year before.
summary.cbdLocalChange	number	Change in local bus speed inside the congestion zone, 2024 to 2025, in percent.
summary.outsideLocalChange	number	The same outside the zone.
summary.slowest	route	The slowest local or Select Bus route.
monthly[]	list	Weekday speed by month since 2019: month, citywide and one field per borough (Bronx, Brooklyn, Manhattan, Queens, Staten Island).
cbd[]	list	Local buses, weekdays 6 am to 8 pm, since 2023: month, inside and outside the congestion zone, in mph.
daily[]	list	Our citywide speed by day: date, weekday (true or false), mph.
routes[]	list	Every route, slowest first. Each is a route, below.

A route has:

Field	Type	What it is
route	string	MTA route, e.g. M50.
borough	string	Borough.
type	string	MTA route type: LCL/LTD, SBS, EXP and so on.
mph	number	Weekday speed over periods.routes.
mphYearAgo	number or null	Over periods.routesYearAgo.
changePct	number or null	Change from a year before, in percent.
ours	number or null	Our speed over our last 14 weekdays.

Speeds are miles over hours summed across routes, so busier routes count for more, as in the MTA’s own figures.

bus-lanes.json

Where buses lose time, for the bus lane map. Coordinates are [longitude, latitude], rounded to about a metre and simplified to within 8 m.

Field	Type	What it is
updated	date	When the file was built.
period.start, period.end	month	The months of MTA data used.
summary.busHoursLost	number	Bus-hours lost each weekday, all stretches.
summary.withoutLane	number	Of those, on stretches without a bus lane.
summary.withLane	number	On stretches with one.
summary.routeMilesWithout	number	Route-miles without a bus lane.
summary.routeMilesWith	number	Route-miles with one.
streets[]	list	The 25 streets without bus lanes where buses lose the most time: street, borough, routes, lost (bus-hours a weekday), mph, lane (share covered, 0 to 1), riders, routeMiles.
stretches[]	list	Every stretch between two timepoint stops. Short names keep the file small; see below.
lanes[]	list of lines	NYC DOT bus lanes, each a list of [lon, lat] points.

A stretch has:

Field	What it is
r	Route.
a, b	Timepoint stops at each end.
mph	Average speed, 7 am to 7 pm.
best	Speed in the stretch’s fastest hour.
delay	Minutes per bus over the best hour’s time.
buses	Buses a weekday, 7 am to 7 pm.
lost	Bus-hours lost a weekday.
perMile	lost per mile.
lane	Share of the stretch with a bus lane, 0 to 1.
c	The stretch’s path, a list of [lon, lat] points.

The same stretches, with full names and no shapes, are in the bus_lanes table.