← Yamama Amir

Plate V · Spatial statistics · New York City, 2024

Mapping the accessibility gap

A third of New York's subway stations have step-free access. Where does the rest of the system leave people with disabilities, and which stations should get elevators next?

Urban Computing Skills Lab · Final project  |  Python · GeoPandas · PySAL · spreg · statsmodels

Spatial clustering of the gap
I = 0.70 p = 0.001
Residents with a disability in hot spots
112,151
Elevators with no backup
314 of 478
Same ten upgrades, chosen better
+47% benefit

The MTA is spending $7.1 billion to make about sixty more stations accessible, and by law the choice has to weigh who lives nearby. Earlier analyses worked at the scale of community boards, about 130,000 residents each, which averages away exactly the differences that matter. I worked with census tracts, about 4,000 residents each, all 2,327 of them.

The measure is the accessibility gap: how much further a tract's residents travel to the nearest accessible station than to the nearest station of any kind. Subtracting the nearest station removes ordinary transit coverage, so a neighbourhood with no subway at all has a transit problem, not an accessibility one, and doesn't count against the system. Weighting the gap by the number of residents with a disability gives person-miles, the burden each tract carries.

Fig. 1 · Person-miles of gap per tract: residents with a disability multiplied by the extra distance to an accessible station. Orange dots are accessible stations; open circles are not. Hatched tracts are left out: no subway within reach, no residents, or a survey estimate too uncertain to use. Hover any tract. No gap 0–40 40–87 87–160 160–271 271+

The gap clusters, and that is the clearest result

Global Moran's I on the gap is +0.70 (p = 0.001): underserved tracts sit next to underserved tracts far more than chance would allow. Local Moran's I finds 161 tracts in significant hot spots, home to 112,151 residents with a disability, and they turn up in every borough: 46 in Brooklyn, 39 in the Bronx, 30 on Staten Island, 24 in Manhattan and 22 in Queens. Much of eastern Queens shows as a cold spot, but its tracts sit on average twice as far from any station as the city's, a transit gap this measure deliberately doesn't count against accessibility.

Not bigger gaps, but more of them

Does the gap fall harder where more people have a disability? Not in the way a correlation would look for. The average gap is flat across tracts ranked by disability rate. What changes is how often a gap exists at all: from about 56% of tracts in the lowest tenth to 69% in the highest (logistic model, odds ratio 1.028 per percentage point, p = 0.001).

Fig. 2 · The 1,604 analysed tracts in ten equal groups, by the share of residents with a disability. Left: the average gap barely moves. Right: the share of tracts with any gap climbs. Hover a group.

Almost nothing survives spatial dependence

An ordinary regression says income, race and density all predict the gap, with very small p-values. But the regression's leftover errors are themselves clustered (Moran's I = +0.67), so those p-values can't be trusted. Refitting as a spatial error model (λ = +0.85) leaves every one of them insignificant. The honest reading is that the gap has strong spatial structure that tract demographics don't explain. Reporting the ordinary regression alone would have produced three confident, wrong conclusions.

p-values, ordinary least squares against the spatial error model
ControlOLSSpatial error
Disability rate0.1630.626
Median income0.00020.730
Percent non-white0.00070.148
Population density0.00170.439

Which stations next

For each of the 332 stations that could be upgraded, I recalculated every tract's gap as if that station were accessible, and summed the person-miles removed. Taking the ten best scores on their own claims 52,255 person-miles. Built together, those ten deliver only 28,916, because six of them sit on the Staten Island Railway and the Queens M and R lines and serve the same neighbourhoods.

Choosing one station at a time instead, and re-scoring the rest after each pick, gets 42,443 person-miles from the same ten upgrades: 47% more for the same budget, and a quarter of the citywide burden.

Person-miles of gap removed by ten upgrades
Ten best scores, as claimed52,255
The same ten, built together28,916
Ten chosen one at a time42,443
The ten upgrades, chosen one at a time
#StationBoroughPerson-miles
163 Dr–Rego ParkQueens6,980
2HuguenotStaten Island5,844
3GrasmereStaten Island4,992
4Baychester AvBronx4,025
5Delancey St–Essex StManhattan3,889
6174 StBronx3,664
7Saratoga AvBrooklyn3,472
8110 StManhattan3,438
9137 St–City CollegeManhattan3,107
10Rockaway AvBrooklyn3,033

Of the twelve stations the MTA announced in July 2025, one, 63 Dr–Rego Park (highlighted), is also first on this list. The others rank between 14th and 289th on this one measure. The MTA's selection weighs criteria beyond what a distance model can see, so this is a comparison, not a verdict.

How much each choice matters

I re-ran the whole analysis under each alternative choice. Two barely mattered. One mattered enormously: counting a station as accessible only if it has a backup elevator or a ramp. On paper a third of stations are accessible, but 314 of the system's 478 elevators have no backup, so when that one elevator is out, the station isn't accessible that day.

The same analysis under each alternative
ScenarioTracts with no gapBurden vs baseline
Baseline39.3%—
Partly accessible stations counted as accessible40.1%−3.1%
Geometric instead of population-weighted centres39.7%−0.2%
Unreliable survey tracts kept in40.6%+17.0%
Only stations with a backup elevator or ramp7.7%+532%

What it adds up to

The gap is real, concentrated, and spatially structured in a way demographics don't explain. It falls on residents with a disability not as bigger distances but as more neighbourhoods with any gap at all. The order of upgrades matters as much as their number: chosen one at a time, the same ten stations remove 47% more of the burden. And the official one-in-three figure flatters the system, because most of it hangs on a single elevator.

Limits