The Chronicle reports a reading of 100 decibels in the Transbay BART Tube. You can't have a conversation at this noise level, but the high pitched irritation lasts perhaps a minute, not long enough to cause hearing loss.
"While a jackhammer may go on for hours and hours and hours, this is pretty much a 20-30 second stretch," said BART Chief Spokesman Linton Johnson.
Johnson says the high pitched screech is caused by the trains rolling over tiny ripples on the tracks which are caused by steel on steel and most prevalent on turns and where the elevation changes.
BART riders talked about the jackhammer comparison.
"A jackhammer? Well I mean it's hard to hold a conversation, but that is kind of extreme. I wouldn't describe it as that loud," said BART rider Ellen O'Donnell.
"I live across the street from the BART station in El Cerrito Plaza and I find it is not so bad living next to it, but when I'm in it, it is actually worse. So I would be happy that there would be some improvement in the sound quality," said BART rider Michael Glassoff.
Rail grinders, purchased a few years ago for $4.5 million each, smooth out those noise causing ripples. You may find it irritating on BART, but it's still better than just about anywhere else in the nation.
"An independent federal report found that we are one of the quietest in the country," said Johnson.
The rail grinders don't remove all the noise, but for short rides, they make the trip hazard free.
The report says that while the Transbay Tube may be the worst, wherever you go on BART there is always a noise level; decibels in the 70s like a hair dryer in some places, in the 80s like a diesel truck in others.
The article also points out that you might want to consider ear plugs.