SAN FRANCISCO (CBS SF) — Road flares left by maintenance crews are the likely cause of two fires in an expansion joint on the new eastern span of the Bay Bridge, a Caltrans spokeswoman said Wednesday.

The fires, one Wednesday afternoon and one Monday night, both started in an expansion joint in the eastbound lanes of Interstate Highway 80 just east of Treasure Island, according to the California Highway Patrol.

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A fire coming from beneath the bridge and up through the expansion joint into the roadway was first reported on Monday around 10 p.m. near the Treasure Island exit. The blaze, quickly extinguished, blocked two lanes of traffic for around an hour.

A second fire was spotted just after noon Wednesday, with lanes reopening around 1:50 p.m.

Caltrans spokeswoman Leah Robinson-Leach said the fires damaged the rubber seal on the joint, which protects it from debris and saltwater, and repairs will be needed. However, the damage has not created any safety hazards for drivers, she said.

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“One of our engineers discovered the fire that was in relatively the same spot as the fire from Monday evening,” Robinson-Leach told KPIX 5.

She said the fires were likely caused by road flares left by maintenance crews doing work on the bridge, but she did not immediately know what the crews were doing or how many flares were left on the bridge.

Caltrans has not yet determined when repairs on the seal and joint will take place, she said.

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