February 19, 2010
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Taking a Look at Today’s Top Technology Issues
BY SUSAN R. PAISNER, Senior Managing Editor
More than ever before—and no pun intended—technology drives public transportation. What are the key issues to look for in the year ahead? Here are some suggestions from an array of experts.
Voltage sag constitutes a major concern of a public transit agency. When a train accelerates, it requires a certain amount of power—the end result of current and voltage. If the voltage is low—that is, if it drops below a specified minimum value—the current must be higher to meet the acceleration power requirement.
Sensitive electronics have difficulty dealing with that circumstance because motors and drive systems heat up from the higher current. When that happens, these electronics don’t respond well, and train performance suffers.
“It’s one of those conditions that reflects a good news/bad news situation,” said David Turner, president of Turner Engineering Corporation. “We got into this situation because we’ve had increased ridership. It’s good that we have riders, but it’s bad because it has increased demand on our facilities and equipment. When it gets to a limit—trains either slow down or they get into a shut down/start up cycle. Either way, it disrupts providing smooth service to passengers,” he said.
Turner called voltage sag a mark of successful rail transportation systems. It happens when there is too much demand for service on a rail line, so when the operator begins running longer or more frequent trains, that increases the demand on the system.
The traditional fix has been to build more traction power supply—either more or bigger traction power stations—but new techniques now available use energy storage systems to help minimize or solve a variety of problems.
Agencies are also trying to reduce large spikes in their power demands because of the additional utility charges that result. To minimize that problem, the transit operators are testing an energy storage system that smoothes the energy demand profile.
When a train is braking, it takes some of the excess energy and puts it in storage. When it accelerates, it draws from storage when voltage is low. This is a primary application being investigated by Los Angeles Metro, MTA Long Island Rail Road (LIRR), and the Washington Metropolitan Area Transit Authority.
New York’s Metropolitan Transportation Authority began experimenting with energy storage in 2000, Turner noted, and is continuing with other efforts now. The Sacramento Regional Transit District has a system in service; Portland’s Tri-County Metropolitan Transportation District of Oregon has also tried this technology; and several other cities are pursuing it “very avidly,” he said. For example, LIRR has a project underway, and Los Angeles Metro received a federal Transit Investments for Greenhouse Gas and Energy Reduction (TIGGER) grant to install what it calls a “wayside energy storage substation.”
APTA’s Energy Storage Research Consortium also is looking into the potential for saving energy and improving performance.
“So there’s a lot of interest in it, both in the U.S. and around the world,” Turner said.
“In terms of transit,” said Stephen M. Hsu, professor of engineering and applied science at George Washington University, “the key thing you look at is not the fancy stuff, but really the invention and development of what we call nano materials.” The classical definition of this term is to assemble atoms and molecules so they can function in a new and unusual way, but Hsu said such assembly is “actually much further away from the current reality—maybe in 10 or 20 years.”
Another class of material, called nano-inserted, injects a nano particle or structure into an existing ordinary material, which then changes its properties and provides a performance that is otherwise not obtainable. According to Hsu, this is a “very big business right now.” However, because of a public misconception that nano technology is dangerous, Hsu noted that the transportation sector is avoiding using the term “nano” while using nano-inserted materials.
Engineers are currently working with clay particles infiltrated with a polymer nano composite, which strengthens the polymers. For example, Toyota and General Motors are both making their materials for SUV step-assist bumpers and undercarriages.
Material of this type is very inexpensive, very lightweight, and very easy to fabricate, Hsu noted, which means a significant increase in fuel economy. Concerning public transportation, he said: “I’m sure a lot of these materials will be introduced as a substitute for metals. You can lower the weight, save fuel economy, and it’s safe and much cheaper. When the yield is high performance and lower costs—that is the key.”
Crashworthiness is not a new technology in itself, but engineers are applying analysis more efficiently now to design structures that can better withstand impacts. Scientists at the Volpe Center, part of DOT’s Research and Innovative Technology Administration, are applying modeling analysis to structures.
One of the most important structural features of crash energy management (CEM) design—a method of designing and manufacturing vehicles in which specific structures within the vehicle are tasked with mitigating the destructive forces unleashed in a collision—is a crush zone at the front end of a railcar. This zone means that, up to a certain speed, almost none of the energy of the crash is absorbed within the occupied areas of the railcar, maintaining its structural integrity.
In addition to the development of CEM design, work is underway to optimize railcar leading ends to make them more “friendly”: that is, to reduce the effect of a collision between an automobile and a railcar.
Steven Kirkpatrick, principal engineer at Applied Research Associates Inc. in San Francisco, is participating in a Federal Transit Administration (FTA) study examining different bumper designs.
“We’ve come up with a preliminary design of a bumper system where we’ve done some work to optimize what a geometric profile should look like to be more compatible with cars,” Kirkpatrick said, adding that the industry term “crash compatibility” means that a train is less likely to do injury to the vehicle it strikes—which is usually a car. The focus, therefore, is to lower the potential for injury to the people in the cars. “We’re not as much concerned with damage to the vehicles as we are with making sure that the people in those cars survive,” he said.
The FTA-sponsored work is completed; Applied Research Associates has submitted its report. Said Kirkpatrick: “This definitely looks like a very promising technology.”
Positive Train Control
Whether it’s called positive train control (PTC) (for mainline commuter applications), communications-based train control (CBTC) (for transit applications), or radio-based signaling (as it’s termed worldwide), it is a major technology focus at the moment. CBTC provides the opportunity to reduce reliance on wayside equipment and its costs while also offering the potential for increased rail capacity by allowing closer train separation since it does not rely on traditional signal blocks. PTC also faces significant interoperability issues, as mandated by the 2009 Rail Safety Act.
This technology, according to industry experts, adds new safety protections that conventional systems may not provide, such as predictive enforcement and its speed limits and movement authorities; automated protection of track workers; and speed enforcement in areas that do not currently use any technology. CBTC is generally installed where there’s already some level of speed enforcement and limit of authority enforcement provided by cap signal systems; PTC provides protection against overspeed operation, enforcement of limits of authority, and protection of track workers.
Electronic Payment Systems
To paraphrase a well-known commercial, this is not your father’s fare collection system. Electronic payment covers much more than fares, including parking lots and tolls. For example, students in universities across the country pay a fee, then use their student ID on the local transit system.
Scott Rodda, senior associate with Booz Allen Hamilton in San Francisco, has worked extensively on this issue. He noted that cities in many countries have implemented electronic fare payment systems: Boston’s Massachusetts Bay Transportation Authority saved more than $10 million the year it introduced the Charlie Card, and in Hong Kong, “you can use your Octopus card to purchase merchandise,” something Rodda said was a possibility here but still “a ways off.”
What else could an improved fare collection system offer? Paying parking meters—and using a cell phone to pay fares. This too, said Rodda, is “still a little ways off, but you’ll eventually be able to have the same utility on your cell phone that you do on your ‘smart’ card.” The major benefit, he said, is that this technology relieves the traveler from the burden of knowing the rules of separate transit systems.
For example, he said, “in the [San Francisco] Bay area, otherwise I’d have to know the exact change to get on and pay—and I might need a paper transfer. It’s a lot of business to know and deal with. But if I had money loaded on my Translink card, I can ride SFMTA [San Francisco Municipal Transportation Agency], BART [San Francisco Bay Area Rapid Transit District], and Caltrain—and not have to worry about exact fare and transfer rules, because it’s all automatically calculated for you.”
When asked why implementation isn’t moving faster, Rodda cited cost as the main barrier. Second was the complicated, sophisticated technology software required to make this work. Lastly, he said: “If you’re implementing a system with multiple agencies, it’s very difficult to get everybody to agree on all the operating rules.”
What else is in the development pipeline? “We’re trying to migrate to contactless credit cards so an agency doesn’t have to distribute a card, since there’s quite an expense in purchasing the cards and distributing them,” he said. Also, there’s the plan to be able to top up the value of a virtual “card” on your cell phone, with the card effectively embedded in the phone. Said Rodda: “That’s the idea, anyway.”
Further, near field communication has enabled any mobile phone in development now to work in place of transit cards using an agency’s current smart card infrastructure in a truly virtual and dynamic transit pass.
APTA’s Fare Collection Workshop in March will cover this topic as well as such issues as the basics of fare collection system design.
These technologies are just a few of the many innovative projects in the pipeline that will advance the public transportation industry. On the pages that follow, APTA members present some of their latest efforts.