What action is required after a failure of both Speed Control and Automatic Train Stop if cab signals are operational?

When both Speed Control and Automatic Train Stop systems fail but cab signals remain operational, the appropriate action is to notify the Dispatcher and limit the train's speed to 40 MPH. This protocol is in place to ensure safe operational practices fall back on the remaining functional safety systems.

Limiting the speed to 40 MPH allows for a controlled response to the failure, reducing the risk of accidents while still enabling the train to continue moving. Additionally, notifying the Dispatcher is essential for ensuring that they are aware of the situation and can provide further guidance, if necessary, or monitor the train's progress.

This response prioritizes safety and communication, recognizing the importance of maintaining some level of operational control even in the event of a significant systems failure. It's crucial to have protocols like this to ensure that the train can be safely managed under less than ideal circumstances.