Which of the following is not a defined speed category?

• A. Limited speed
• B. Medium speed
• C. Express speed
• D. Slow speed

Answer: (C)

Understanding which speed categories have official definitions helps you know what rules apply in different parts of the track. In SMT-1, there are defined speed levels such as slow speed, medium speed, and limited speed, each tied to specific operating rules, required precautions, and braking considerations. Express speed isn’t one of these defined categories, so there isn’t a standard set of procedures or a fixed maximum speed labeled as “Express.” If a section requires a higher speed than the slow category, you’d refer to the actual track speed, timetable authority, or posted limits rather than an undefined “Express” category. So the choice that isn’t defined is Express speed.