cab and block signal areas

How can I tell if the CTA subway train is in a cab or a block signal area?

In cab signal territory, just wait for the beep...

Presently all of the CTA "L" system is cab-signal territory except the Blue line from about Halsted-UIC through the Dearborn Milwaukee subway. So you should hear the beeping all over. In the last year the wayside signals have been converted over to cab signal on the Forest PK branch of the Blue line. The Blue line subway signals are being converted next. There are still wayside signals, double aspect, at interlockings. In the State ST subway and being installed on the Loop there are wayside signals that will allow trains to close in on their leader at stations. This is quite a change from the 1940s when the CTA took over. Then there were only semaphore signals at towers. There were no wayside signals with train stop anywhere except the city owned signals in the city owned State ST subway. The Lake Street "L" was the first to have cab signaling installed in the 60s with the introduction of the Pullman New Look cars and the elevation of the street running at the west end.

David Harrison