CHICAGO, Feb. 4 (UPI) -- The drivers of two Chicago commuter trains that collided, sending 45 people to the hospital, will undergo drug and alcohol screening, investigators said.
The slow-speed collision Tuesday near the Merchandise Mart just north of Chicago's Loop left many of the 1,200 passengers directly involved in the crash stranded on the trains for hours and resulted in 45 others being transported to area hospitals.
No fatalities were reported.
The Chicago Transit Authority and the National Transportation Safety Board said train drivers were to be given routine drug and alcohol tests, the Chicago Tribune reported Wednesday.
A network of electronic signals tells train operators when they can move forward and requires them to stay several hundred feet apart. If the electronic signals fail, CTA guidelines require operators to get clearance from the control center before continuing.
Because the operator of the rear train did not seek clearance, the accident appears to have been caused by human error, an official said.
