Photo: Santiago Mejia / The Chronicle
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The distinct, high-pitched screeching sounds of BART, familiar to most riders going through the Transbay Tunnel — and now, apparently, video game players — is a well-worn topic of discussion.
“Why Are BART Trains So Loud?” asked KQED’s Bay Curious.
“Will BART damage my hearing?” inquired KALW.
The Chronicle also addressed this in 2010, asking, “Noise on BART: How bad is it and is it harmful?“
Which is to say, noise is a complaint that BART hears (ahem) often. Despite the incoming new fleet of cars — which the transit agency promises will be much quieter than the current trains — BART has continued to make improvements on its legacy fleet in order to reduce the noise for riders in the meantime.
In order to get that done, the crew at BART has taken on the laborious process of reshaping the wheel on every car, while also smoothing out more than 1,000 miles of track. There are more than 100 miles of BART tracks, but the tracks require 10 passes to smooth out for this project.
The underground noise most riders hear is caused by wear known as rail corrugation, or “speed bumps that develop on the rail,” as BART Principal Track Engineer Gregory Shivy described it. By reshaping wheels and the refinished tracks, BART rides are almost 20 decibels quieter than before, according to BART officials.
As of February, BART has reached its goal of reshaping every wheel to the new, quieter, conical shape.
And by all accounts the efforts seem to be working: The team tracked a 73 percent reduction in noise complaints by line, from the start of the project in July 2017 to October 2018. Informal tests done by SFGATE using the National Institute for Occupational Safety and Health (NIOSH) iPhone app does seem to show an improvement over noise measurements made by The Chronicle in 2010.
“The silence is actually golden in this case, because we’re not getting the complaints, and for a long period of time, almost nothing,” said Ben Holland, manager of vehicle systems engineering with BART. “We’ve had some upticks [in complaints] here and there, [but] I think people that ride the system frequently, they remember how just incredibly loud the cars were and when the system gets quiet, they’re gonna say, ‘Oh my goodness, it’s so much quieter.'”
Relating a story of taking his own family on BART, Holland recalled everyone being able to chat with each other during a notoriously noisy stretch of BART. “I didn’t even realize it, we were carrying on a conversation through the Transbay Tube, and partway through I’m like, ‘Wow, I don’t ever remember being able to do that.'”
The improvements are all being done despite the fact that 775 new cars are scheduled to take over the tracks in 2022 — and are built with quietness in mind.
“First of all, the cars are new so, they’re not rattling as much,” said Shivy. “Second of all, just the materials that are used on the new cars, there’s a much higher focus on selecting materials that reduce noise.”
“If you ride our existing cars, you’ll hear the doors rattling, you’ll feel air coming through them,” Shivy added. “And wherever you feel air, that’s where you’re going to hear noise, because that’s how the noise travels.”
Comparing the new to old cars, noise measurements drop anywhere from 3 decibels, to as high as 6 to 8 decibels “in certain conditions,” said Shivy.
Still, if you’re riding on one of the older trains and things feel like it’s in the 85-plus decibel range, the good news is that it shouldn’t typically be an issue. According to Dr. Matthew Fitzgerald, Assistant Professor and Chief of Audiology at Stanford University, there isn’t data to suggest the noise levels experienced when riding BART could result in permanent hearing loss.
“[What] we know about sustained noise exposure is, at high intense levels, it can cause hearing loss,” explained Fitzgerald. “We know that sometimes even short bursts of very intense noise, called an impact noise, can also be associated with hearing loss as well.”
“We don’t have data suggesting that [BART will damage hearing], and that’s not to say that it might not be a problem,” he said, “[but] we don’t have a lot of data showing that that has a permanent effect on hearing loss.”
So, in theory, with all the improvements to the BART trains and track — as well as the new, quieter cars on its way to BART — riders should feel fairly confident they aren’t causing damage to their hearing via a BART ride.
The one caveat to this all, however, is for those riders wearing headphones.
“When people are not careful with the levels of music that they have, and they’re listening to podcasts or music, and you’re turning it up so that you can hear it over the noise in the tunnel, or other places,” said Fitzgerald, “then you could run the risk of getting up to some pretty high levels that might be problematic.”
Fitzgerald said he’s observed riders on the New York subway with “a bad set of earbuds” that don’t isolate the ear, cranking up the volume to intense levels for an extended amount of time. To help protect hearing — beyond the sage advice of keeping your headphone volume low — Fitzgerald suggested investing in a good set of headphones, particularly over-the-ear, or closed-back kinds, or earbuds that form a tight seal from outside noise. (For those looking to lower the noise levels without music capabilities, Fitzgerald said custom ear plugs also work wonders.)
“That’s an easy way to kind of help protect your hearing, particularly when you’re in a noisy environment, you won’t have to crank up what you want as loudly to get over the external noise,” Fitzgerald concluded.
“I encourage people to be cautious — and don’t be afraid to plug your ears,” he added.
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This post was originally posted at https://www.sfgate.com/bayarea/article/BART-noise-levels-decibels-trains-headphones-loud-13602734.php.