Three doors on new train cars to reduce noise, improve reliability, increase capacity
By MELISSA JORDAN
BART Senior Web Producer
What a difference three doors can make.
Of all the thousands of decisions that went into designing BART's new train cars, one -- a change in the number of doors -- may prove one of the most momentous.
For 43 years now, riders have known the familiar BART train cars with two doors on each side. All that changes with the new Fleet of the Future cars, which are scheduled to begin arriving for testing later this year.
"The issue we have today is that people are concerned they can't get off a crowded train, so they cluster near the doors," said Henry Kolesar, group manager for vehicle maintenance engineering. When that happens it takes longer for every to get off and onto the train, which increases "dwell time" -- the amount of time a train sits in the station before it moves again.
"We have to keep the trains moving and keep the schedule to stay on time as best we can," he said. Three doors will help do that. The switch to three doors has multiple benefits, actually, but three of the most important are: noise reduction, reliability improvement and capacity increases.
RELIABILITY AND NOISE
"Micro-plug" style doors are designed to be quieter than the current style of door
The new three-door design uses a different technology. The existing cars have "pocket" style doors that slide into and out of a slot. "It's a very simple design and very widely used," Kolesar said. There are some downsides, however: the closing seal is not totally snug, so noise is increased. Also, there are more motors needed to open and close this style of door, and thus more moving parts to potentially break down.
The new doors are "microplug" doors -- imagine those on a minivan. They open on the outside of the train in a tiny space, less than an inch outward, and slide open. When they slide back closed again, the seal is tight. "That will significantly reduce noise" coming from outside the doors, Kolesar said. The doors also use fewer "operators" or motors to open and close them. So despite having more doors overall, there will be fewer moving parts and greater reliability expected.
Like everything about the trains, they are tested extensively. Cycles of a million openings and closings test their endurance. Machines to simulate a person leaning on the inside of the doors, pushing on the sides of the doors, almost every conceivable issue, are used to test their performance. Like current doors (and in fact the standard used in the rail industry) the doors are designed NOT to re-open if a person holds them. The standard warning will apply: STAND CLEAR, THE DOORS ARE CLOSING! Doors do not re-open for "one more person" because there is always "one more person" coming down into a crowded station, and trains would essentially never be able to get out of stations.
"These are not elevator doors," Kolesar said. "It will be important for passengers to know that the same safety rules apply on the new trains. Don't try to hold the doors open, or you may take the train out of service for everyone."
"We're running a railroad and the most important things are to be safe and on time," he said.
CAPACITY
By itself, the three-door model doesn't provide more capacity. But because the new trains' layout is configured to allow more open space, more people can get on the train confident they can get in and out without a struggle.
In this image of a car body under construction, you can see three side doors.
"The amount of time it takes people to exit would theoretically be cut by 50% because the number of doors is increasing by 50%," Kolesar said. Actual performance will be tested when the trains arrive.
Any regular rider knows what it's like now. You've been courteous and moved to the center of the train so others could board. At each stop, more people board, and board, and board. When you get to your stop, you are like a salmon swimming upstream to get close to one of the two doors and position yourself to get off. "Excuse me, pardon me, coming through, getting off at this stop" -- you've heard or said them all.
With three doors, the swim gets shorter. In addition, there will be more trains in the fleet, eventually allowing every train to be a 10-car train, and thus increasing actual capacity. For more details go to www.bart.gov/cars Trains can't be longer than 10 cars because that's all the platforms are built to accommodate.
Decisions made decades ago like how to build the platforms create physical limitations for the BART system. As one example, being a hybrid commuter-city rail, we have long straight aerial stretches in the suburbs and tight pretzel curves underneath some cities. Some stops are several minutes apart and others only a few seconds, a couple of blocks. Speeds must change accordingly.
To glide safely over the aerial structure that crisscross our rolling hills and valleys, BART cars must also be built very light -- and are the lightest in the industry for their given performance, in fact. "We have to eke out all (the gains in capacity and timing) that we can, and one of the ways that you do that is to go to three doors," Kolesar said.
Meet the Fleet is an occasional series looking in-depth at features of BART's new train cars.
Check out our previous features:
Meet the Fleet: Improved climate control highly anticipated on new trains