They were added after the wreck in 1972 when an older single decker telescoped into a new double decker that missed a stop and backed up. Worst Chicago wreck ever. 45 died. Many more would have but the accident happened next to a hospital. They were literally giving blood transfusions to survivors still in the wreck.
Given the catenary supports a black car among black catenary supports on a curve was almost impossible to see from a distance. Hence the bright orange. Also didn’t help that as the first train backed up the signal cleared from red to green for the following train.