What speed must you maintain when passing over a wheel impact detector?

When passing over a wheel impact detector, it is essential to maintain the maximum speed permitted. This detector is designed to assess the impact forces exerted by train wheels as they pass over it, which helps identify potential issues with the wheels or track. Operating at the maximum speed ensures that the detector can accurately gauge these forces under conditions representative of typical operational speeds.

If a train were to travel at a speed lower than the maximum, the measurements could be skewed, potentially leading to incorrect assessments of the condition of the wheels or infrastructure. Acknowledging that maximum speed allows for a comprehensive evaluation of the train's mechanical integrity while ensuring safety and efficiency during operations. The other options do not align with the operational requirements for accurate data collection from a wheel impact detector.