A railroad tie on the Caltrain tracks in Palo Alto shut down train service on Friday afternoon, Caltrain spokeswoman Christine Dunn said.
The incident occurred before 4 p.m. after a train engineer spotted the wooden tie smoldering. Police and fire departments halted all trains through the area, which is between the Churchill Avenue crossing and the California Avenue station.
Police and fire personnel searched the tracks on foot. The smoldering tie was reported at milepost 30, four-tenths of a mile north of the California Avenue station and north of Peers Park, Dunn said.
A similar incident occurred earlier this week. Dunn did not know the cause of the smoldering ties, she said.
"It's the first time I have ever heard of anything like this," she said.
Firefighters did not locate the smoldering tie, according to dispatch. They planned to clear train passage soon.