Compared with many of those posting on transit geek sites I have participated in, and the signal engineers at New York City Transit where I once worked, I’m not an expert in subway and road capacity. But compared with those who have been making an issue of it, well, in the country of the blind the one-eyed man is king, so I’ve elected to provide an overview of what I know in a post. Before getting technical, however, the most important thing about the capacity of the region’s rail transit service is this: there is more room on the tracks than the region will ever be able to use during most of the day; the only capacity problems are during the AM and PM weekday peak periods, and the only severe capacity problems are during the peak hour within those periods. Meanwhile, the streets of Manhattan and some parts of the outer boroughs are congested for much of the day, and in some cases increasingly congested as the day goes on. That is because during the AM rush hour, the capacity of the bridges and tunnels entering Manhattan, and their approaches, limits the number of vehicles on the streets, but as the day goes on more and more are present and trying to move. During peak hour most people are already taking transit, so congestion pricing is more likely to shift drivers to transit during the off peak period, when there is plenty of room to add more riders and, if needed, trains.
According to the Hub Bound survey http://www.nymtc.org/files/hub_bound/2004_Hub_Bound.pdf , a long running series of data produced by the New York Metropolitan Transportation Council, people arriving in Manhattan south of 60th Street during the hour from 8 am to 9 am account for 20.8% of those coming in via transit all day, but only 6.6% of those arriving via motor vehicle, based on 2004 data, the latest available. The total number of motor vehicles in the CBD peaks at 1:00 pm. This data shows that by 2004 the number of motor vehicles was already soaring toward prior peak levels following the recession and restrictions of 9/11. Put another way, mass transit (and walking and biking) already accounts for 87% of people entering the CBD during the peak hour, from 8 am to 9 am (see Table 14), compared with just 13% for autos, taxis, vans and trucks. During the entire peak period, from 7 am to 10 am, the transit plus share is 83%, leaving 17% for motor vehicles. During the rest of the day, however, the transit share is just 59%, leaving 41% for motor vehicles. Only 77,900 of the 1,171,619 people that entered Manhattan south of 60th on a typical fall day via autos, taxis, vans and trucks did so from 8 am to 9 am, when the subways are most crowded and some lines are unable to add more trains.
So what limits the number of trains run during that peak hour? Many things do, and whichever one is the lowest common denominator is the maximum number of trains that can be operated.
On most routes, the main constraint is the number of trainsets regional transit providers own, and the number of crews available to operate them. If ridership on those lines increases, this could be solved by hiring more crews and buying more trains. If the labor situation were different, in fact, capacity could be increased by reducing how often transit employees were sick (a very high number by private-sector standards) and shifting maintenance to off peak hours (at the cost of some overtime if overnight). According to the national transit database, only 5,200 of New York City Transit’s subway cars are in revenue service at the peak, but the total fleet was over 6,200 last I checked. The rest of the cars are receiving scheduled maintenance during rush hours (one reason the cars are more reliable than in the past). It should be noted that from 1940 to 1947, when transit ridership was at a peak, the subway system had just over 4,800 cars, though several older elevated lines, since demolished, were also running with wooden cars.
If New York City Transit were to acquire more cars it would also need a place to store them overnight, when fewer trains are running. The transit yards, however, are also at capacity although some are being expanded when they are rebuilt if room allows. Further expansion would require the acquisition of property, at huge expense. Already a shortage of yard space requires some trains to be stored out on the right of way overnight, where they are vulnerable to vandalism. No transit buff would say where.
The maximum number of trains that can be operated on a line with a conventional signal system is, I believe, 30, a figure the new CBTC technology — which will be rolled out over 30 to 50 years IF financial pressures do not cause the MTA capital plan to once again disappear — increases to 40. Only one subway line (the Queens Boulevard Express), however, runs as many at 30 trains per hour. The rest either could run more trains if trainsets and crews were available, or are constrained by other factors.
One is dwell time, or the maximum amount of time a train is stuck in a station as passengers board and exit. If it takes 2.5 minutes to get a train through the most crowded station, you can’t run more than one train every 2.5 minutes, because the additional trains would just back up. The most crowded subway station is Grand Central on the Lexington Avenue line, where huge volumes of passengers get off, get on, and transfer between the local and the express. The subway stations at Penn Station were built to make it impossible to transfer between local and express trains to limit dwell time, but at Grand Central there wasn’t enough room. Since dwell time is the reason there aren’t more express trains on the Lex Express, signal improvements alone cannot reduce crowding. Only the Second Avenue Subway can.
Terminal capacity is an additional constraint. If it takes four minutes to turn around trains at the last station on the line, then you can’t run more than 15 trains per hour even if the signal system would permit 30. And that was the situation of the Canarsie (L) line, until CBTC increased terminal capacity to 20. Unlike the Flushing Line (#7), the Canarsie line does not have tail tracks past the last station. So the signal system must force trains to crawl into the 8th Avenue station, to ensure that no matter what they will not crash into the wall at its end. This, and the need for trains to cross over a switch entering and leaving that station, backs up trains on the line and limits the maximum number of trains that can be run. On the Flushing Line, in contrast, trains can pull into Times Square at higher speeds, since if they run the red signal at the end of the station the emergency brakes will still have a long distance to stop them.
Other terminals have other constraints. Fears of terrorism have cut capacity on the Lexington Avenue local (#6), because to make certain someone cannot carry a bomb below City Hall NYCT now makes certain everyone is off the train before turning it around. That takes time, and backs trains up entering City Hall Station.
In the end, however, the final constraint on peak hour capacity is money. Buying more trains and hiring more crews at peak hour would cost some money. Reconstructing terminals and merge and diverge points that limit capacity would cost more money. Building East Side Access, the Second Avenue Subway, Metro North to Penn and Access to the Region’s core would cost enormous money.
Adding trains off peak and at the fringes of the rush hour, on the other hand, would cost very little money. Most of the cost of rail transit is fixed. No matter how many people ride, the cars, stations, and right of way have to be maintained, the stations and signals have to operated and manned, and debts, pensions, and retiree health care must be paid for. Those working for RTO, which includes both signal operators and train operators/conductors, account for only 30% of those working on the subway; train operators and conductors account for perhaps 20%, a figure that could fall if one person train operation is more widely implemented. Compared with the rest of the cost, adding a few train crews to run trains the MTA already owns on tracks it already maintains through stations that are already open costs very little.
Service is less frequent of the fringes of rush hour than at rush hour, and less frequent in the mid-days and evenings than at the peak. That means transit service is less good, particularly on commuter railroads. If, as a result of congestion pricing, more people chose to use transit off peak rather than drive, however, transit agencies could afford to add service, since the additional cost would be modest enough that the additional revenue could cover it. Better service would attract more riders, permitting better service, etc. etc. And, the goal is not to have no one drive — if that happened the city’s highway and street capacity would be wasted, and no revenues would be collected. The goal is to have fewer people drive, so that highway and street capacity is not overwhelmed. In 2004, shifting 20% of those arriving via motor vehicle at peak hour (about 20,000 people) to transit would have increased peak hour transit ridership by just 3.7%. And some of those might simple choose to carpool to divide the cost of a congestion fee.
Transit service and stubbornness are not the only reason people drive to Manhattan during the day. Some have raised the issue of those traveling to and from the hospital complexes along the East River, far from the nearest subway line. Manhattan’s East Side, in addition to its large residential population, is a huge activity center in comparison with anyplace but the CBD. But the Second Avenue Subway would make a transit ride to far East Side employment centers better. And, moreover, no alternative to congestion pricing is realistic if it doesn’t include a substitute source of transportation funding. Indeed congestion pricing alone doesn’t cover all the costs, both those that will be experienced in the future and those from the past that, as a result of decisions by Governor Pataki and the state legislature, will have to be paid for in the future. Those whose alternatives involve coming up with ways to spend more money without raising more revenues are simply being dishonest (or should I say more dishonest than average).
Transit capacity is limited during peak hour, but could be expanded, and is abundant otherwise. Street capacity cannot be expanded much further without inconceivable costs per additional driver, costs that are higher in Manhattan than anywhere else. Ultimately, there is a limit to the number of motor vehicles that can accumulate in central areas without reducing the quality of life for everyone, including the drivers themselves. The choice is to live with congestion, or to find some way to ration scarce space on the street.
The current policy is to hand out free on-street parking permits to some people, while discouraging others from driving by restricting new public parking garages (allowing the existing ones to charge higher fees), and having those who don’t have the connections to get the permits and can’t afford the garages and drive around and around trying to find the remaining legal on-street spaces. Meanwhile, because there is congestion, the current policy is to do everything possible to facilitate motor vehicle traffic, thereby limiting the amount of public space available for other purposes. I don’t find this setup particularly fair, though it works to the benefit of many of those in the political class. But in any event, it hasn’t worked.