PLEASANTON — Several eastbound Altamont Commuter Express trains were delayed by up to nearly two hours Tuesday after heat warped the tracks, an ACE spokesman said.

"With extreme heat such as this, the tracks kink and Union Pacific has to go inch-by-inch checking them," spokesman Thomas Reeves said. "It's a very long process."

The No. 4 train, which was supposed to arrive in Stockton at 5:45 p.m., was delayed between the Fremont and Pleasanton stations until at least 7:20 p.m.

The No. 6 and No. 8 trains, which were stuck behind the first one, were also delayed by nearly two hours.