Which term represents the speed governed by cab signals, with a normal maximum of 30 mph and up to 40 mph in ASC territory?

• A. Limited Speed
• B. Maximum Authorized Speed (MAS)
• C. Medium Speed
• D. Restricted Speed

Answer: (B)

Maximum Authorized Speed is the speed the cab signaling system authorizes the train to travel at. It reflects the current signal and track conditions, so the engineer adjusts speed to stay at or below that limit. Normally this MAS is 30 mph, but in ASC territory it can rise to 40 mph. This term is the correct fit because it specifically names the speed authority conveyed by the cab signals, whereas other terms refer to different kinds of speed limits or operating rules that aren’t the cab-signal authorized speed. In practice, you monitor the cab signal display and ensure your speed never exceeds the MAS shown; if ASC territory allows up to 40 mph, you may go up to 40 provided conditions are safe and compliant with all signals and rules.