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What Are the True Operating Cost Differences Between bus and Light Rail?

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Light Rail train in station
Gary Conner/Photolibrary/Getty Images

What Are the True Operating Cost Differences Between Bus and Light Rail?

One of the never ending arguments in the battle between bus (especially bus rapid transit) and light rail is which costs more. From the perspective of capital costs, it is clear that light rail costs more to build than bus rapid transit, due to the requirement for tracks, the electric catenary, electrical substations, and other infrastructure that buses do not need. In addition, light rail lines likely need their own garages, while bus rapid transit lines can store their buses at existing bus depots . The difference in capital costs greatly diminishes is true BRT - buses operating on exclusive rights-of-way like in Ottawa, ON - are built instead of "lite" BRT, which is basically express or limited stop buses operating along the street.

In terms of operating costs, it is often argued that light rail is cheaper to operate than buses because the fact that the capacity of light rail is so much greater than buses allows for fewer light rail trains to be run than buses operated along a corridor for the same number of passengers. It is true that one light rail train consisting of three sixty feet long cars can carry as many people as four and one-half regular buses. What this means is that assuming passenger load remains constant, a light rail train that has three-car consists operating every ten minutes would need to be replaced by standard buses operating almost every two minutes (six light rail trains per hour = 27.5 standard buses per hour). If there is enough demand along a corridor to operate buses every two minutes, then a light rail train would have lower operating costs than buses.

Unfortunately, with few exceptions - including almost none of the cities shown in the accompanying table - American cities do not have bus corridors that have sufficient demand to operate buses every two minutes. Instead, cities are choosing to operate their light rail lines as often or more often than existing bus service. Replacing a bus route operating every fifteen minutes with even a two-car light rail train operating every fifteen minutes is the equivalent of increasing corridor capacity by three hundred percent (a two-car light rail train is the equivalent of three standard buses). While ridership is likely to increase due to the introduction of trains, it is unlikely to increase by three hundred percent.

In fact, it would be nice if transit agencies built light rail lines along already busy bus transit corridors, but unfortunately many of them do not. For every Phoenix that built its first light rail line along the path of the city's busiest bus route there are Denver and Salt Lake City, two places who decided to build light rail lines along existing railroad and freeway rights of ways rather than where transit demand is located. In fact, the busiest bus routes in both Denver and Salt Lake City are nowhere near where the rail lines are built.

All of the above would be bad enough if it cost the same amount to move one bus and one light rail vehicle. Unfortunately, as the table below shows, it is much more expensive, on average, to move one light rail vehicle as it is one bus. The table, which shows operating costs per hour for one bus and one light rail vehicle for fifteen American cities with both bus and light rail lines (data is from 2010 and 2011 via the National Transit Database website), shows that is costs almost twice as much on average to move one light rail vehicle per hour versus on bus ($233 per hour for one light rail vehicle versus $122 per hour for one bus).

The table shows a much wider range in the cost of operating light rail vehicles ($124.01 - $451.33 per hour) than buses ($84.61 - $163.96), although if we throw out the two outliers in light rail costs (Los Angeles and Dallas) the range is reduced to $124.01 - $292.51. It is unclear to me why Dallas and Los Angeles light rail costs are so much greater than the other agencies.

There are several reasons why it would cost more to operate one light rail vehicle versus one bus. First and foremost there is the cost of maintaining the track right of way and associated switches and signaling. Second, there is the cost of maintaining the light rail stations and associated parking lots - including the cost of employing ticket collectors, security, and maintenance workers. Finally, in certain cases the cost of electricity to operate the trains may be greater than the cost of fuel for buses - a trend that is likely to continue in the future as electricity prices are driven higher due to requirements to include alternative energy sources while transit agencies continue to take advantages of low prices for natural gas brought about by the current glut in supply. In fact, a major Southern California transit agency reported an almost 500% increase in operating costs per mile when they replaced natural gas buses on a route with electric buses .

Overall, it is more expensive to operate one light rail vehicle than one bus. Because of this fact, cost-effective use of light rail requires a large passenger demand - a demand that only exists in a few American cities, most of which already have extensive rapid transit systems. While rail may be more attractive to the choice rider, should we really put the financial stability of our transit systems at risk by building and operating light rail lines in areas that do not have enough demand to support them?

Light Rail Versus Bus Costs for Fifteen American Cities With Both (Source NTD)

Light Rail vs Bus
Cities
City Bus Cost Light Rail Cost
Dallas $122.38 $451.33
Salt Lake $118.24 $124.01
Denver $102.76 $170.18
Sacramento $119.51 $232.00
Los Angeles $127.28 $391.43
Portland, OR $134.39 $187.55
Minneapolis $123.64 $183.82
Phoenix $102.82 $180.35
Baltimore $163.96 $246.73
Philadelphia $141.34 $166.26
Boston $142.96 $216.45
San Diego $84.61 $137.67
Cleveland $126.12 $292.31
Buffalo $114.23 $280.97
Mean $121.87 $232.82
Max $163.96 $451.33
Min $84.61 $124.01
Median $122.38 $216.45
SD $19.50 $90.89
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