The head of the Federal Railroad Administration, Joseph Szarbo, recently told a crowd that one two-track rail line can carry as many people as a sixteen-lane freeway. While the exact numbers may vary, rail advocates often make similar statements to claim that rail lines are somehow more efficient than roads. Yet they are flat out wrong.
To reach this conclusion, rail advocates who actually make any calculations typically compare railcars stuffed to “crush capacity,” the kind of crowding sometimes found in Asia but that Americans consider unacceptable, with automobiles filled at average occupancies. This is blatantly unfair; either the average number of occupants of railcars should be compared with the average for automobiles or full rail cars should be compared with full automobiles.
Typical light- and heavy-rail cars have about 70 seats and room for about 80 more people standing. While some railcar manufacturers claim that more than 80 standees can be crammed into the cars, Americans will rarely accept such crowding. For safety reasons, most light-rail lines can only move about 20 trains per hour, while some heavy-rail lines can move as many as 30 trains per hour.
The hourly capacity of a rail line is equal to the capacity of each railcar times the number of trains per hour times the maximum number of cars in a train. In order to avoid blocking traffic, light-rail trains are limited by the length of city blocks, which in most cities means three-car trains, but in a few means just two or as many as four cars per train. Since heavy-rail trains by definition don’t operate in streets, they can be longer but the length is limited to the length of station platforms. The Washington Metro system allows eight-car trains, but some lines on the New York City subway system allow as many as eleven-car trains.
The capacity of light rail with three-car trains, then, is about 9,000 people per hour. For New York City subways, the maximum number is slightly less than 50,000 people per hour. For the Washington Metro, which can only handle 28 trains per hour, the number is about 33,600 people per hour.
Modern freeway lanes can support about 2,000 vehicles per hour. If the average vehicle has five seats and every seat is filled, that represents about 10,000 people per hour–more on just one lane than on a three-car light-rail line. That means two tracks of a New York City subway line that can support 11-car trains have about the same capacity as ten freeway lanes, not sixteen. All other rail lines in America, including many New York City subway lines whose platforms can’t support 11-car trains, have much lower capacities.
As long as we are imagining maximum capacities, why limit cars to five passengers? Why not imagine everyone has a 15-passenger van? That would increase the lane’s capacity to 30,000 people per hour, nearly as much as the Washington Metro system. Or imagine a freeway lane is used exclusively by buses. Since buses are longer than cars, the lane would support only about 1,000 buses per hour. Standard buses have 40 seats and room for about 25 people standing, so the bus lane would have a capacity of 65,000 people per hour. Capacities could be increased still further by using double-decker buses, which have about 80 seats and room for at least 25 people standing, resulting in a freeway lane capacity of 105,000 people per hour, more than twice the New York City subway.
This doesn’t mean buses can replace subways, for most New York subways parallel not freeways but city streets. However, a single city street can support lots of buses. Portland once had a bus mall with staggered bus stops on which it scheduled 160 buses per hour. With 40 seats and room for 25 people standing, the bus mall could move more than 10,000 people per hour. Ironically, Portland added light rail to the bus mall, which actually reduced the capacity of the mall to move people.
The numbers for transit are even worse when counting actual ridership instead of maximum capacities. The average automobile carries about 1.67 people, which means–if it has five seats–it is about a third full. Transit vehicles are typically far emptier than that. Over the course of a day, the average number of people aboard a light-rail car is about 25, which is about a sixth of its capacity. The average number of people aboard a heavy-rail car is about 27.5, less than a fifth of its capacity. The average number of people aboard a transit bus is about 11, also less than a fifth of its capacity.
In other words, if you are the only occupant of a five-seat SUV, your car still is filled to a higher share of its capacity than the average bus or rail transit vehicle. In actual practice, no two-track light-rail line in America moves as many people per day as one freeway lane, while the only two-track heavy-rail lines that move more people than one freeway lane are in Boston, Chicago, New York, Philadelphia, and Washington, and the only ones that move more than two freeway lanes are in New York. Considering that construction of one mile a two-track rail line typically costs 20 to 100 times as much as a mile of freeway lane, the freeways are far more cost-effective at moving people.
If the goal is to move a lot of people into a downtown or other job center, buses can move as many as trains in all but a few, very rare circumstances. New York City has 2 million jobs in a seven-square-mile section of Manhattan, and it is likely that only trains could bring that many people to work each day. The Chicago Loop, America’s next-largest single job center, has about 500,000 jobs, and while a lot of those commuters take trains to work, it is remotely possible that buses could do the job.
Four other urban areas–Boston, Philadelphia, San Francisco, and Washington–have between 200,000 and 400,000 downtown jobs, while five more–Atlanta, Denver, Houston, Los Angeles, and Seattle–have between 100,000 and 200,000 jobs. Since fewer than half of the workers in most of these downtowns take transit to work, buses with one or more downtown bus malls should be able to handle commuters at a far lower cost than rail.
Sadly, once a light-rail line is built, its low capacity actually generates support for more such lines. “The trains are filled up at rush hour, so they must be a success,” proponents will say. In fact, if the trains ever fill up, it is because their capacities are so low. Since buses can serve a wide range of demands, from a few people to 100,000 people per hour all at about the same cost per rider, buses make a lot more sense than rail in almost any situation.
The truth is that most cities don’t really need high-capacity transit because they don’t have a lot of people going from point A to point B. The great thing about buses is that, for about the same cost per passenger mile, they can provide low-capacity service that meets low demand, medium-capacity service that meets medium demand, and high-capacity service that meets high demand. Rail can’t do this; it works only in very high-demand situations and then only if it has an exclusive right-of-way. Light rail and other low-capacity transit simply can’t carry enough people, even if the demand exists, to justify the cost.