When Speed Control and/or Automatic Train Stop fails en route but cab signals work, what must the Engineer do?

When Speed Control and/or Automatic Train Stop failures occur while cab signals remain operational, the appropriate response is to notify the Dispatcher and limit the train speed to 40 MPH unless directed otherwise. This response ensures safety by enforcing a speed restriction that mitigates the risk associated with the failure of critical safety systems like Speed Control and Automatic Train Stop.

The cab signals still provide information to the Engineer about the track ahead and any restrictions in place, which means operations can continue but with caution. By restricting the speed to 40 MPH, it allows the train to be operated safely while ensuring that the Engineer has enough time to react to any signals or conditions encountered on the track.

The other options suggest different actions, such as maintaining maximum speed, stopping immediately, or proceeding without any speed constraints, which would not prioritize safety under these circumstances. Adhering to the set speed limit reflects both a fundamental understanding of operating protocols in the event of such equipment failures and aids in maintaining overall safety on the railroad.