But because of the design, one of the wheels ends up getting dragged against the rail on turns, which causes that high-pitched squeal. “So one wheel has to be sliding while the other is rolling,” Kolesar says.
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Testing has shown a drop of as many as 20 decibels in sound intensity. One way to think about the difference is if the decibel level of riding on a BART train with the old wheel profile and rail sounded like standing near a lawnmower the new system is more like being next to a dishwasher.
Rail corrugation (a periodic wear pattern resembling corrugated metal) causes tonal noise and vibration; fine, short-wavelength corrugation is known as roaring rails due to its high-pitched sound, whereas coarse, long-wavelength corrugation can cause the ground and nearby buildings to vibrate.
The reason that trains honk their horns so much at night is because it's dark and the trains aren't so easy to see. Even though the lights are on, you sometimes can't see them coming, especially around the many blind curves that Gilroy has, like the one near Leavesley and the one near the train station.
BART actually has a big machine that grinds down the bumps on corrugated track, eliminating some of the noise. This explains why sometimes a portion of the BART system makes loud uuunnnhhh sounds one day and doesn't make a peep the next. You aren't crazy -- they just smoothed out the track at night.
Sounds above 150 dB have the potential of causing life-threatening issues. Sounds between 170-200 dB are so intense that they can cause lethal issues like pulmonary embolisms, pulmonary contusions, or even burst lungs.
BART has 8 DMU train cars which each have a seating capacity of 104. 70 mph maximum; 35 mph average, including 20-second station stops. For BART to Antioch DMU trains, the maximum speed is 75 mph; 60 mph average.
The majority of the old cars will be recycled. The Fleet Disposition Team will manage the process, including selecting which parts should be harvested from retired vehicles and choosing which cars with the highest failure rates get retired first.
BART agency is on par with similar agencies. In Philadelphia its lower 66-percent, and in Boston higher marks 73-percent. But when it comes to train cleanliness, BART isn't doing as well. Just 62-percent of riders give BART a satisfactory rating.
When it rains, BART also alters its computer programs to slow the acceleration of trains in certain areas to prevent them from spinning their wheels. But those delays, he said, are typically less than 30 seconds. It's nothing that would be noticed by passengers, he said.
This is the deep clean -- BART's all-out, every-nook-and-cranny effort to fight back against whatever the Bay Area throws at or into these trains. Every 400 hours we come in, Burditt explained. From top to bottom. Each car takes two people and about two to three hours to complete.
Taking BART, he noted, is also faster than driving the highly trafficked highways into San Francisco. “Being on BART makes me feel relieved. It's way more stressful driving,” he said. “It's tough commuting this far, but public transit makes it more manageable.”
Engines may be left idling to maintain important safety related functions such as maintaining engine temperature, air pressure for the brake system, the integrity of the starting systems, the electrical system and providing heating or cooling to a train's crew and/or passengers.
We might be susceptible to sleep while in a car, bus, train, plane, or boat because of multiple factors, including the vibrations and the white noise, the sensations representative of being in the womb, the boredom, or simply the fact that we're tired.