Metra trains will operate at a Grateful Dead rather than a Red Hot Chili Peppers tempo over the weekend.
In other words, crowds of Lollapalooza fans boarding trains and hot temperatures may slow the system down, agency officials cautioned Friday.
The rock music festival runs through Sunday and already extra riders piling on cars caused some delays Friday, Metra spokeswoman Meg Reile said.
Plus with temperatures soaring to more than 95 degrees, the system will be instituting heat-related speed restrictions. Trains will run about 10 mph slower than normal to compensate for any track irregularities caused by the hot weather, which can cause the steel to expand. The top speed on Metra trains is 79 mph.
Speed reductions will "reduce the compression of the weight of the train and stress on the rails as it goes over them," Reile said.
The agency is adding some trains on its BNSF and Union Pacific North Lines and increasing the number of cars on other lines.
Restrictions will be in place on alcohol and glass containers throughout the festival as well as bicycles.
For details, go to metrarail.com/metra/en/home/service_updates/service_to_lollapalooza2012.html.