The G train is bad. I say this, 16 years after I moved to New York, 11 years after I left, and I know it’s what every New Yorker knows. Tourists walk too slowly, rent is too high for small apartments, and the G train sucks. What I want to highlight in this post is how the subway’s scheduling paradigm is especially bad for the G train and leads to a vicious cycle making the train less frequent and less useful for passengers.
The role of the G train
The G train is the only mainline subway service in New York that does not enter Manhattan; see map here. It connects what are now the region’s two largest non-Manhattan business centers, Long Island City and Downtown Brooklyn, running vaguely parallel to the East River on the Queens and Brooklyn side of it. To the south of Downtown Brooklyn, it has a tail serving the wealthy neighborhoods collectively called South Brooklyn, such as Carroll Gardens and Park Slope.
I’ve criticized the G before for its poor construction. It misses critical transfers, like the other lines built in the IND program in the 1920s-30s. In Queens it misses Queensboro Plaza and the transfer to the N/W trains on the Astoria Line, and in Brooklyn it misses every single non-IND line except the L (and, at a suboptimal location, the R). This already makes it less useful as a circumferential line – such lines live on convenient transfers to radial lines, because direct O&D service is less valuable to secondary destinations than to primary ones.
But what I realized last week, commuting from Long Island City to Downtown Brooklyn, is more delicate. My hotel was near Queensboro Plaza, which the G doesn’t serve, but the station is served by the 7, which connects to the G one stop away at Court Square; Marron’s new office is in Downtown Brooklyn right on top of the Jay Street station, on the IND-built A/C and F trains, which is either a cross-platform connection or a short walk from the G. So for my trip, the connections worked. And yet, I was regularly facing 10-minute waits on the shoulders of rush hour, and on the subway countdown clock I saw a 15-minute gap.
To explain what went so wrong that the G should have such low frequency at 10 in the morning, it’s necessary to explain how New York City Transit decides the frequency of each service during each time of day.
New York City Subway frequency
In New York, the system for deciding the frequency of each subway service at each time of day is based on average peak crowding. This means that for all trains using the service in a given time period, the crowding level at the peak crowding point of the journey is averaged; frequency is adjusted so that off-peak the peak crowding level is 125% of seated capacity, and at rush hour it is based on published standing capacity per car that works out to about 300% of seated capacity depending on car design.
This system is done per numbered or lettered service. Thus, for example, the 2 and 3 trains run on the same track most of the way, but where they diverge, the 2 is considerably busier, and therefore the 2 runs slightly higher frequency (most ridership on the 2 and 3 is on the shared segment, not the tails). As a result, on the shared trunk, there cannot be perfect alternation of 2 and 3 trains; a few times an hour, a 2 train is followed by another 2 train, which means that on the tail, the frequency is uneven. When two 2 trains follow each other with no 3 between them, the leading 2 train is more crowded than the trailing one; this variation is averaged out in the guidelines – it is not the busiest train that sets the frequency guidelines.
These guidelines are not a good way to timetable trains. The above example of how it can create uneven crowding on the 2 is one problem with this system; if instead there were regular alternation of 2 and 3 trains then the 2 would be persistently slightly more crowded than the 3, just as today there is uneven crowding whenever two 2 trains run with no 3 in between, but the frequency on both the shared trunk and the branches would be more regular. This is especially important on more complexly interlined parts of the network, where the current system leads to large programmed gaps between trains occasionally.
The G is not very heavily interlined; the issue there relates to another criticism of the guidelines, which is that they assume travel demand is fixed. If the ridership on a train is independent of frequency, which it is if the headway between trains is very short compared to the trip time (say, if the trains run every 2-3 minutes), then the sole purpose of service is to provide the capacity the passengers need, and so the guidelines make sense as a way of rationing service convenience. However, in reality, the elasticity of ridership with respect to service provision is not zero. Three years ago I did some analysis of New York’s situation and the existing literature on ridership-frequency elasticity, suggesting it is equal to about 0.4. So the low frequency of the G deters ridership, which then appears to justify the low frequency.
But 0.4 < 1. And I believe that there are two reasons why on the G, and on circumferential lines in general, the elasticity of ridership with respect to frequency should be higher.
Circumferential lines in general tend to have shorter average trip time. Between two nearby spokes, say between Downtown Brooklyn and Williamsburg, they are the only real option; between two farther away ones, a direct radial may be an alternative.
The G is different from (say) the Ringbahn in that it misses most transfers, but this should not impact this pattern too much. The missed transfers in Downtown Brooklyn weaken the G for short as well as long trips involving a connection there. In contrast, in the middle the G does make the most important transfer, that with the L, and only misses the weaker J/M/Z.
The 0.4 estimate for ridership elasticity with respect to frequency assumes average behavior for trip length. But if trips are shorter, then the impact of frequency is larger. The 0.4 estimate comes out of an estimate of about -0.8 of ridership with respect to generalized trip time, which includes in-vehicle time, walk time, and wait time, the latter two given extra weight to account for transfer penalty. If one of the three components of trip times is shortened, the other two grow in importance.
The role of options
The G is not usually passengers’ only choice for making the trip. They can connect in Manhattan, or, in some cases, go directly via Manhattan, for example taking the N or R from Downtown Brooklyn to Queens (in the opposite direction, they serve separate station so it’s a harder choice, leading to asymmetric demand). Going between Marron and the East Village, Eric Goldwyn could connect to the L via the A/C/F or the G; I never once saw him use the G, only the lines via Manhattan.
I have not seen the impact of different transit paths on demand elasticity in the literature. It is likely that the elasticity in such case must be higher, because it is standard in economics that demand is more elastic for goods sold on a competitive market than by a monopolist.
Note also that it is to the overall system’s benefit to convince passengers to switch from radial lines to the G. The G is less crowded, so such a switch distributes ridership better on the system. And the G starts out much less frequent, so that even on a fixed operating budget, the impact of a service increase on the G on ridership is larger than on an already frequent trunk.