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[IMAGE]elec.jpg[/IMAGE]Electrified rail systems appear to be making a comeback. With streetcar systems in Portland and Seattle; light rail systems in Phoenix and Sound Transit's newly opened Central Link light rail service, there's no doubt that electric traction-powered rail is experiencing a boom. In addition to purpose-built electrification projects, some diesel-powered systems are also looking to get onboard by converting.
Pros and Cons
When you compare electrification versus diesel, the benefits overwhelmingly favor electric. In this time of eco-consciousness, the fact that electrified rail generates lower greenhouse gas emissions than diesel is one of the most obvious benefits. In its upcoming switch to electric traction power, San Carlos, Calf.-based Caltrain expects to reduce air pollutant emissions by up to 90 percent.
Electrified rail systems achieve faster top speeds and accelerate much quicker, and don't require refueling, says Eric Scotson, Parsons Brinckerhoff's manager, West Region, Transit & Rail Systems. "You don't have to carry the weight of the diesel fuel around with you either, which can be in the thousands of pounds, so that makes a big difference," he adds.
Regenerative braking also makes electric traction technology much more efficient. "When you are accelerating, you use the motors to drive the train. When you want to brake, you use the motors as a generator to slow the train," he says. "The generated power can be pushed back into the system to be used by other trains, or what we are expecting in the future is we'll actually be able to push some of it back into the utility company and save both power consumed and power paid for."
Electric engines are easier and less expensive to maintain, while maintaining large diesel engines is difficult and requires highly skilled mechanics to maintain them. In addition, most diesel-powered locomotives are actually diesel-electric, so you have to maintain the diesel engine and the electric motors, Scotson adds.
The downside to electrified rail is the cost, which can be substantial due to the infrastructure involved, such as the overhead contact system or third rail, and building of power substations. But, while capital costs are high, the overall lifecycle cost is a lot more favorable to electrification, says Scotson.
Overhead contact systems, required by both high-speed and light rail systems, may also be viewed as a negative in the aesthetic sense. "To the general public, catenary wires might be seen as unnecessary clutter," he says.
Looking to make the switch
One such transit agency looking to make the switch from diesel to electric power is Toronto, Ontario-based Metrolinx's GO Transit rail service, which has run diesel commuter trains over existing track that was in place for CN (Canadian National Railway) and CP (Canadian Pacific Railway) freight services. GO Transit's rail service comprises seven lines, with a total of 242 miles of track. "More recently, we've begun to acquire some of the rail bed lines in the Toronto area, but historically, we are in effect a tenant, rather than some cities where you have purpose-built electric lines," says Metrolinx President/CEO Rob Prichard.
The agency has been considering electrification on and off for more than 20 years, he explains. "We decided this spring that we needed to do a systematic and comprehensive study of the benefits and costs of the undertaking, and to think hard about sequencing and the priority we should assign the different corridors if we're not able to electrify all at once."
To that end, the Metrolinx Board of Directors recently established a Community Advisory Committee that will work with the agency to assess the benefits, impacts and costs associated with converting the existing railway, as well as define the scope of and recommend terms of reference for a study to be done by a consulting firm. The electrification study is scheduled to be completed by December 2010.
"We need to think hard about the cost, not just in dollar terms, but in terms of foregone investments in further expansion of infrastructure," Prichard says. "Because it may be that we get more cars off the road and have a bigger environmental and transit impact to building more infrastructure instead of converting our existing infrastructure to electric."
Enhancing service power
A rail service that is already in the process of going the electrified-power route is Caltrain. The commuter rail line, which runs one line on 77 miles (50 mainline and 27 commute-hours only) of track from San Francisco to Gilroy, is in the design phase of its project, with construction slated to begin in 2011 and revenue service set for 2015.
The project scope will include electrifying 52 miles of track from San Francisco to San Jose (the San Jose-to-Gilroy section is owned by Union Pacific and would continue to run diesel trains). Two traction-power substations and eight auto-transformer stations will be installed, with a capacity of 172 trains at peak five-minute headways. Cost of the electrification infrastructure is estimated at $608 million, while $397 million is tabbed for railcars.
An overhead contact system will be installed to provide power to trains up to 90 mph, with the capability to support the alignment for the San Francisco-to-San Jose section of the California High Speed Rail Authority's line, which will travel along the Caltrain rail right-of-way.