Updated: July 19, 2013 11:41AM
A downed wire on the South Chicago branch of Metra’s Electric Line caused an extensive backup of trains Friday morning.
The downed wire at 63rd Street supplies power to the trains, Metra spokeswoman Meg Reile explained. While Metra continued to investigate the cause as of about 9:30 a.m., there is a possibility it may have been heat-related, she said.
After the wire fell, two trains were caught in “a dead-zone” with no power, Reile said. The passengers were moved to other trains, but as of about 9:30 a.m. those two trains were still on the inbound tracks.
Metra has been operating Electric Line trains on a single track through the affected area, but delays on some trains have been an hour or more. Because of the single-track operation, Reile said the emphasis was on getting passengers heading inbound on moving trains before the less-crowded outbound trains were cleared to go through.
She noted that the wires not only supply power for the trains to move, but for their air-conditioning systems, so that’s been an added motivation for Metra crews to move the larger numbers of passengers to working trains.
According to a Metra rider alert, the wire problems at 63rd were affecting about a dozen trains and crews have been working to correct the problem.
Throughout Metra’s system, riders were being alerted to prepare for delays as train operations were in heat reduction mode because of the extreme heat and humidity in the Chicago area.
Metra says that when temperatures exceed 95 degrees, it’s necessary to operate the trains at reduced speeds to compensate for heat-related stresses on tracks, switches and signals. Reile said trains were running “a minimum of 10 mph” slower than normal.
Metra says that during this heat event, they will have all resources on standby so crews can quickly respond and restore service, but riders on all trains may experience delays of 10 to 15 minutes.