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By Bob Calverley
The USC News Service
University of Southern California engineers say that high technology could improve low-tech bus service but not without changing the habits of bus drivers and passengers.
"We want to see if intelligent transportation systems (ITS) technologies can improve bus scheduling," says Randolph Hall, Ph.D., associate professor of industrial and systems engineering at the USC School of Engineering and associate director of the school's Center for Advanced Transportation Technology. "Most bus schedules have a lot of slack in them. If you could reduce the slack through better control, you could provide better service without having to purchase more buses."
Dr. Hall and Maged Dessouky, Ph.D., assistant professor of industrial and systems engineering at USC, tested global positioning systems (GPS) that precisely track buses with satellites, mobile data terminals that enable drivers to send passenger data to other drivers and control centers, and electronic fare boxes that help reduce boarding time.
According to Hall, buses are trying to mimic the "hub and spoke" systems in which airlines funnel many flights into a single airport at roughly the same time so that passengers can connect to destination flights with minimal waiting. When incoming flights are delayed, airlines must decide whether to hold or release the connecting flights.
"Bus systems now face the same kinds of dispatching decisions," says Hall, "but they lack the information they need to make them real-time information regarding vehicle locations and the number of passengers intending to transfer."
Hall and Dr. Dessouky used simulations of Metropolitan Transit Authority (MTA) bus lines to see if ITS technologies could benefit transfer passengers.
"ITS could save about 20 seconds per passenger per transfer," Dessouky reports. "Such minuscule gains probably wouldn't justify the expense of installing the new technology, but we think the impact of ITS technologies on the rest of the system might yield more significant benefits and savings. That's what we plan to investigate next."
ITS technologies could certainly make drivers more effective and speed the transfer of passengers, but both drivers and passengers would first have to change their ways, says Diane E. Bailey, Ph.D., assistant professor of industrial and systems engineering at the USC engineering school.
In another USC study, Dr. Bailey and her students recently rode Orange County Transit Authority (OCTA) buses to observe drivers as passengers boarded and debarked at 300 stops. The two factors most likely to delay buses at stops, they found, are passengers asking questions and passengers in wheelchairs getting on or off the bus.
According to Bailey, bus-stop information kiosks with displays to answer passengers' most common questions might save drivers some time, but they would be expensive to install at all stops.
Bailey says that passengers are more likely to ask questions at minor stops than at major ones. Furthermore, they usually ask questions while boarding, so information displays aboard buses would be ineffective.
"Even if a low-cost solution could be found, it's not clear that passengers, especially elderly ones, would resort to the information display when a driver is there to answer their questions," says Bailey.
Bailey says displays could provide information about shops, parks, and other places of interest along routes, but the interaction between drivers and passengers an important social function would suffer.
"It would clearly detract from quality of life if accompanying policies were to forbid discussion with the driver, or if drivers were instructed to direct passenger queries to the system instead of responding in person," she says.
A relatively simple and inexpensive telephone call-box system could warn drivers when a wheelchair passenger is expected to board further along the route. This information could allow the driver to attempt to gain the extra time before stopping to pick up the wheelchair passenger. Drivers should be able to accomplish this because both USC studies indicate a surprising amount of slack in bus schedules.
Dessouky says it has generally been assumed that, once behind schedule, a bus continues to fall further behind -- causing other buses on the same route to bunch together. Passengers see this phenomenon when, after a long wait at a bus stop, two or three buses all show up at once.
"We found that bunching does not occur with long-headway buses," Dessouky reports. "There's sufficient slack for subsequent buses to slow down or catch up." Headway is the time or distance between buses, so a long-headway bus is a good distance ahead of the next scheduled bus on that route. Long-headway buses are most common in suburban areas or late at night.
"Southern California has a lot of long-headway buses. OCTA service is almost entirely provided by long-headway buses," says Hall.
When Bailey and her students rode eight OCTA bus routes, six of the buses began their routes late and two began on time, but only one bus finished late one of the two that started on time, showing that drivers can generally catch up if they fall behind schedule.
Hall believes that ITS technology could arm drivers with the information to better pace their buses so that they adhere to the schedule over the entirety of their runs.
"It's not just efficiency, but also a matter of public safety when passengers have to wait at a bus stop after dark," he says.
OCTA has begun installing GPS technology on its buses, and the researchers predict that the price of the technology will continue to drop. They believe GPS might be most useful when a bus breaks down, giving authorities the exact location of the bus before a replacement vehicle is dispatched.
All three of the USC researchers strongly believe that bus systems are worthy investments, especially in Southern California.
"We've been oversold on trains," says Hall. "People in Los Angeles have the impression that trains are much better than buses. For far less money, you can provide greater benefits with buses."
The USC studies were funded by the California Partners for Advanced Transit Highways at the University of California, Berkeley; Caltrans; and USC’s Southern California Studies Center.
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