SAN FRANCISCO (CBS SF) — Bay Area Rapid Transit and Caltrain trains were being slowed down along the system Friday and through the weekend because of the heat wave in the region, the agencies reported.

BART says its rails are heat-treated but when outside temperatures reach extreme levels, it’s possible the rails can expand and cause them to buckle.

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Trains will be slowed down in outdoor parts of the system between noon and 8:00 p.m. Friday through Sunday to allow operators more time to react if they see any abnormal train conditions, BART said.

Passengers were told to expect an additional 10 to 20 minutes added to their travel times during those days, although there may be changes depending on how long the hot weather lasts.

“The technician said over the intercom we’re going to slow down a bit as we arrive at the station. We just slowed down a little bit,” said Concord BART Passenger Teresa Arakawa.

Late Friday afternoon, they said the hot temperatures were also caused equipment problems, resulting in additional delays.

Passengers say more time in the train means more sweating.

“Every stop, Rockridge, Orinda, Lafayette,” said Arakawa. “By the time we got over here, I was starting to sweat.”

Caltrain announced slower speeds along its system as well in a Twitter post.

As of 3:22 p.m. a level two heat restriction had been issued for all main tracks between Burlingame and San Jose. A level two heat restriction is issued when the temperature climbs above 105 degrees.

Caltrain officials said the restriction means conductors can operate passenger trains at no more than 50 mph and freight trains at no more than 30 mph.

As of 3:24 p.m. a level one heat restriction had been issued for all main tracks between San Francisco and Burlingame, meaning conductors can operate passenger trains at no more than 60 mph and freight trains at no more than 40 mph.

Caltrain spokeswoman Tasha Bartholomew said the heat restrictions will be lifted “only when the temperatures come down.”

As of 3:22 p.m., San Francisco International Airport’s Airtrain, which takes travelers from BART to the airport’s terminals, was down. Limited service was restored by just before 6 p.m., according to the SFO Twitter account.

In addition, there will be no BART service during the Labor Day weekend between 19th Street and Fruitvale stations or between West Oakland and Fruitvale stations, while Lake Merritt station will be closed as crews rebuild trackway in the downtown Oakland area.

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