Q: What is "light rail"?

A: Light rail is a type of transit service that operates relatively light weight, self-propelled (usually by electric motors) vehicles that have steel wheels that run on standard steel rails. The technology is basically the same as that of streetcars (called trams in some countries), although light rail systems usually operate on separate rights of way rather than streets for most of their length and provide faster service than streetcars. Numerous cities in the U.S. have recently constructed (or are constructing) light rail lines, including Seattle, in which one is being built from downtown to Sea-Tac International Airport. For a complete list of U.S. urban areas that have light rail and other rail transit systems in operation or under construction, please visit the page Rail Transit Systems in the U.S.

Q: What is the difference between light rail and heavy rail?

A: Light rail uses smaller and lighter weight vehicles than heavy rail. It is also more flexible, in that it is capable of running in streets and in transit malls in addition to its own right of way, and it can usually accommodate sharper curves and steeper grades. It is also typically much cheaper to construct and operate.

Q: What is the difference between streetcars and light rail?

A: They use very similar technologies. A main difference is that light rail lines usually operate mainly on exclusive rights of way (i.e., on the ground, in tunnels and on elevated structures) whereas streetcars usually operate mainly in the streets. This is one reason that light rail generally provides faster speeds than streetcars; others include the facts that the stops are typically spaced farther apart and the vehicles are designed for higher speeds. In addition, light rail vehicles are usually larger and have greater passenger capacities. However, the differences are not always clear, as some streetcar lines have light rail-like characteristics and some light rail lines run on streetcar tracks for part of their routes.

Q: Does light rail have any advantage over monorail?

A: Yes, it has a number of important advantages. One is that it is generally much cheaper. Another is that it has much greater flexibility with regard to routing. That is, light rail can run on elevated structures, in tunnels, on its own right of way on the surface, in streets and in transit malls. But monorail can only run on elevated structures. Also, it is very easy for light rail vehicles to switch between tracks, such as at junctions of lines, but monorails require bulky and complex beam movement mechanisms (as monorails really run on large concrete beams rather than rails).

Q: Is it true that most new light rail transit systems are failures?

A: No, this is a myth. Actually, the opposite has been the case; most new systems have been huge successes, even in regions that are dominated by automobile transportation. For example, the new, two-line light rail system in Salt Lake City carries close to 60,000 people a day, far higher than original projections. The Blue Line light rail between Los Angeles and Long Beach carries more than 85,000 passengers on the average weekday. For more misconceptions about light rail and rail transit in general, please visit the page Rail Transit Myths -- And Realities.

Q: What is the reason for the recent surge in construction of light rail transit systems?

A: The past several decades have seen a surge in the construction of rail transit systems in the U.S., particularly in light rail and commuter rail systems, and in much of the rest of the world as well. This is a result of several factors, including rising fuel prices, growing concern about air pollution, realization that busses are not a good solution for heavily trafficked routes and advances in rail transit technology. This surge is readily apparent from looking at a list of rail transit systems and their opening dates, such as Rail Transit Systems in the U.S..

Q: Will this rapid pace of construction of light rail transit systems continue?

A: Yes, and it may even accelerate. Acceleration could come about as a result of still higher fuel prices and mounting concern about climate change. Another important factor is the growing acceptance, and even welcoming, of rail transit by the public and politicians because of the great success of recent new systems and thus the desire to extend them and build similar systems elsewhere.

Q: Is light rail appropriate for Seattle?

A: In general, rail transit is quite appropriate for the Seattle metropolitan area. This is because of the large and still increasing population, heavy congestion on major freeways and growing concern about sprawl and protecting the environment. The problem is not with rail transit itself, but rather with how it is implemented, particularly route selection and cost control.

Q: Why is there so much opposition to Sound Transit's plan to bring light rail to the Eastside via the I-405 floating bridge?

A: There are a number of reasons. One is that it could be very disruptive of long established residential neighborhoods south of downtown Bellevue. Another is potential problems with converting the two center lanes on the I-90 floating bridge to rail. One such problem is the possibility that it could actually reduce overall passenger capacity on the bridge because only a few trains could be allowed on the bridge at one time due to weight restrictions. Another objection is the fact that Sound Transit has overlooked the most important and least cost corridor for rail transit on the Eastside, which is the I-405 corridor. Moreover, Sound Transit's plan calls for completion of the line through Bellevue by the year 2027 and to downtown Redmond at some unspecified date after that, which is a long time to wait.

Q: Would light rail be appropriate for the Eastside railroad right of way?

A: The Eastside railroad right of way has a number of conditions that make it very appropriate for rail transit service, including (1) traversing an area of high and still rising population density, (2) paralleling the most heavily congested freeway in the Northwest, (3) running right by downtown Bellevue (which already has the second largest urban core in the state) and (4) having existing track connections to rail lines to Tacoma and Everett. However, the initial emphasis should be on starting a transit service as quickly as possible and at the lowest practical cost, and then considering adding a light rail capability as passenger traffic continues to increase. The fastest and most economical way to begin transit service on the line would be to use DMUs (diesel multiple units) and/or existing Sounder heavy rail commuter trains, some of which could be routed up the Eastside from Tacoma and through Kent via the existing track connection west of Renton.

Q: Why would it take longer and cost more to start a light rail service on the Eastside railroad than to use DMUs or Sounder trains?

A: Because it would require the construction of overhead wires to supply electricity to the light rail vehicles. Diesel powered vehicles, of course, do not need such wires.

Q: Would it be possible to convert the Eastside railroad to light rail in the future without disruption of any existing diesel powered transit service?

A: Yes, this is quite possible. It would be more costly than shutting down the line completely for the duraration of the construction. However, this added cost would most likely be greatly outweighed by the benefits of keeping the line in operation during construction.

Q: When and why would it be desired to convert the diesel transit service to electrically powered light rail?

A: When passenger volume and the frequency of operation reach a certain level, electrical operation can start to offer some important advantages despite the much higher initial cost. These include lower operating costs because the electrical motors are more efficient than diesel engines. They also include reduced maintenance costs. In addition, vehicle acceleration is faster, trains are quieter and the emission of pollutants from internal combustion engines is eliminated.

Q: Would conversion to light rail mean the end of freight service?

A: No. Freight service could run on the same tracks. This is done on several light rail systems in the U.S., including San Diego and the River Line in New Jersey.