(KRON) — Bay Area Rapid Transit (BART) is undergoing rebuilding work at two stops over the weekend, which will impact service. The yellow, orange and green lines will all be affected.

On Saturday and Sunday, free AC Transit buses will replace trains between the South Hayward and Union City stations. The maintenance will be going on all day and will impact the orange and green lines. Only the orange line will run between the Berryessa and Union City stations.

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On Sunday, the yellow line will run on a single track through the Pleasant Hill/Contra Costa Centre Station. Delays of 10-15 minutes are expected.

The repair work at the Pleasant Hill Station is being performed after a train partially derailed between the Pleasant Hill and Concord stations on June 21. BART said that high temperatures were to blame for the incident, as they caused the rail to curve and misalign. BART will be repairing track ties on Sunday.

The South Hayward/Union City construction will happen four more times, next on July 30-31. There will be single-tracking on the yellow line on two more Sundays: August 14 and September 4. To plan your trip ahead of time, use BART’s trip planner.