In New York, there are two dedicated subway tracks on the Manhattan Bridge offering a bypass of Lower Manhattan. Between DeKalb Avenue in Brooklyn and Canal Street in Chinatown in Manhattan, Q trains run nonstop for 3.5 km, while the R train goes the long way, taking 5.5 km and making 2 intermediate stops in Downtown Brooklyn and 4 in Lower Manhattan. The N skips DeKalb Avenue, with a 4.5 km nonstop segment between Canal Street and the Atlantic/Pacific/Barclays station complex.
The Q and N should be immense time savers. Instead, the Q does the trip in 8 minutes and the N in 10, both of which average 26-27 km/h. The subway’s overall average speed, weighed down by local trains stopping every 700 meters, is 29 km/h. The Q and N are still time savers, though, because the R does the 5.5 km in 18 minutes, an average speed of 16 km/h – far less than the systemwide average, and even less than the slowest Paris Metro line, Line 4 with its 500-meter interstations and 20 km/h average speed. Between DeKalb and Pacific, about 800 meters, the R takes 3 minutes. Unfortunately, New York City Transit is not taking any measures that would fix this, and when I asked about one possibility, I got excuses.
There are two reasons why this part of the subway is so slow. The first is something called signal timers. Timers are devices installed at frequent intervals on long interstations, such as the bridges and tunnels connecting Manhattan with Brooklyn and Queens, limiting train speed. These timers have always been around, but after fatal accidents in the 1990s, New York City Transit tightened them, reducing speed further; for some more background, see my Vox piece from last summer. The timers are more safety theater than safety. The biggest conclusion I reached from looking at the accident postmortem on the NTSB and some NYCT information was “make sure your trains’ brakes work as intended”; NYCT derated the trains’ service and emergency braking rates later in the 90s, which marginally reduces maintenance costs but is bad for safety and brutal for train speed.
The second reason is the switches at DeKalb Avenue. DeKalb is a six-track station, with four tracks feeding the Manhattan Bridge and two feeding the tunnel through Lower Manhattan. The two tunnel tracks then continue to the south as local tracks on the Fourth Avenue Line, carrying the R; this is the least used of all subway trunk lines into Manhattan, because the detour and low speed make it useless for most Midtown-bound passengers. The four bridge tracks include two express tracks at DeKalb going to the Brighton Line, and two super-express tracks skipping DeKalb continuing to the south as express Fourth Avenue tracks. Today, there is a splitting and recombining of branches. The B and D run together from Sixth Avenue to the Manhattan Bridge, and the N and Q run together from Broadway, but just north of DeKalb they recombine as B and Q running to Brighton, and D and N running super-express down Fourth Avenue.
This recombination at DeKalb slows down trains considerably, in two ways. First, the interlocking is complex. You can see it on this map on NYCSubway.org; in addition to splitting and recombining the B, D, N, and Q, it also has a non-revenue connection allowing R trains to serve the Brighton Line. Trains on diverging turnouts go at glacial speeds. And second, trains from four lines influence one another’s schedules, and delays propagate. Supervising train movements is thus difficult, and control center has to have a camera watching the trains enter the interlocking to ensure they adhere to schedule; timetables have to take the resulting delays into account.
When I first complained about reverse-branching in New York, I talked about capacity limits imposed by having more trunk lines than branches, a situation that is still to some extent true going north and east of Midtown. At DeKalb, there are six tracks going in and six going out, but the recombination makes things slower, and should be removed. NYCT should make a decision between having B and D trains run on the Brighton Line and the N and Q on Fourth Avenue, or the reverse. The interlocking permits either option, with entirely grade-separated junctions, allowing the trains on the two lines to no longer interfere with each other’s operations.
I in fact asked NYCT about it by proxy. NYCT dismissed the idea, on the grounds that transfer volumes between the B/D and N/Q would be too big. At Atlantic/Pacific, the Pacific side has a cross-platform transfer between the local R and express D/N, but going between the Pacific side and the Atlantic side (the B/Q, and separately the 2/3/4/5) involves a lot of walking. NYCT believes that passengers would flood the corridors looking for a train to their preferred destination, and the transfer volumes would require trains to have long dwell times. NYCT said nothing about whether the overall speed would actually fall, but I believe that based on the large transfer volumes NYCT predicts, passenger trip times (including transfer times) would rise. The only problem: I don’t believe NYCT’s prediction is true at all.
The B and D trains go express up Sixth Avenue, making stops at Grand Street in Chinatown, Broadway-Lafayette on Houston Street, West Fourth Street in the Village, and Herald Square. The N and Q trains go express up Broadway, serving Canal Street in Chinatown, Union Square, and Herald Square. North of Herald Square the two lines are never more than one long block apart until they leave Midtown. Passengers going toward Midtown are unlikely to have strong opinions about which of the two lines they would prefer.
Passengers going to destinations between Manhattan Bridge and Midtown might register stronger preferences. Union Square is the fourth busiest subway station in New York, and is quite far from the B and D. The closest alternative using the B and D is to change cross-platform to the M or F at West Fourth, and get off at 14th Street and Sixth Avenue, two long blocks from Union Square. Three more stations are potential concerns: Canal Street ranks 18th, West Fourth ranks 21st, and Broadway-Lafayette ranks 25th. Getting to Broadway-Lafayette from the N or Q is easy: the station and Canal Street are both on the 6, and passengers can transfer to the 6 at Canal.
West Fourth and Canal remain concerns, but they are not huge ones; they are secondary destinations. Canal is only a major destination for Chinese-New Yorkers, and in Brooklyn they cluster in Sunset Park along Fourth Avenue, suggesting that the Fourth Avenue express tracks should carry the N and Q and the Brighton tracks should carry the B and D. The urban geography of Chinese-New Yorkers is changing due to the combination of fast immigration and fast integration and migration to the suburbs, but this is a service decision, not an infrastructure investment; it can be reversed if demographics change.
Moreover, as a destination, West Fourth is predominantly used for NYU. The Village is a dense residential neighborhood, and West Fourth allows its residents to easily reach Lower Manhattan, Downtown Brooklyn, and two different four-track trunk lines through Midtown. But it has few jobs, outside NYU, which lies mostly between Sixth Avenue and Broadway. Union Square can adequately serve people going toward NYU, and stations on the R and 6 to the south can serve people going to NYU even better. The one problem is that the transfer between the R and the N/Q at Canal Street is not cross-platform; the cross-platform transfers start at Union Square. But with coverage of multiple stations walkable to NYU, the loss of the one-seat ride to West Fourth is not fatal. Even the transfer to the A, C, and E trains at West Fourth has alternative options: passengers from the N or Q going to the E can transfer to the F or M at Herald Square and reach the same stations, and passengers going to the A or C can transfer to the 1 at Times Square and to the A or C at Columbus Circle, both of which transfers are not much harder than climbing two flights of stairs at West Fourth.
With so many options, not many riders would be connecting at Atlantic/Pacific, and trains could keep dwell times short. If anything, dwell times might be shorter, because missing a train would be less fatal: the next train on the same track would serve the same destinations in Midtown, so riders would only need to wait about 3 minutes at rush hour, and 5 minutes off-peak. The gain in speed would be substantial, with the interlocking imposing fewer operational constraints.
NYCT might need to slightly rework the switches, to make sure the chosen matching of the lines in Manhattan and Brooklyn takes the straight and not the diverging direction at the turnouts; typically, the straight direction imposes no speed limit (up to full line speed on high-speed rail lines), but the diverging direction is slow. A matching in which the B and D go on Brighton and the N and Q on Fourth Avenue express to my understanding already involves only one diverging move, if I am reading the track map linked on NYCSubway.org correctly. At the same time, NYCT could fix the switches leading to the R: there was through-service from the Brighton Line to the tunnel tracks the R uses today, but there no longer is, so this out-of-service connection should get diverging and not straight moves. But even with the R, the capital investment involved is minimal.
I do not know the potential travel time gains between DeKalb and Canal Street (or Grand Street) with no timers or reverse-branching. With straight tracks across Manhattan Bridge, and wide curves toward Grand Street, 3.5-minute trips are aspirational, 4-minute trips are still possible, and 5-minute trips should be easy. From Pacific Street, add one more minute, corresponding to cruising at 50 km/h, a speed limit the subway routinely attains even on local tracks. This saves passengers from DeKalb about 4 minutes, and passengers from Pacific about 5. The average trip across the system is about 21 minutes, and the average delay (“excess journey time“) is 3 minutes. The saving would be immense, and contribute to both more casual ridership between Brooklyn and Manhattan, and lower operating costs coming from faster trips.
NYCT should not make excuses for this. The timers may have been originally justified as a safety improvement, but reducing train braking rates had the opposite effect. And, uniquely among the various reverse-branch points in New York, DeKalb feeds two Manhattan trunks that are very close to each other, especially in Midtown, to the point that one-seat rides to every stop have limited value. It should make a decision about whether to run the B/D together on Fourth Avenue and the N/Q on Brighton (switching the Q and D) or the reverse (switching the B and N), based on origin-and-destination data. Some passengers might bemoan the loss of one-seat rides, but most would cheer seeing their trips sped up by 4-5 minutes.