Why is the bottom bracket higher on a track bike?

Track bikes have higher bottom brackets (lower BB drop, typically 55–62mm versus 65–75mm for road bikes) to prevent pedal strike on the steeply banked turns of a velodrome. When a rider leans into a banked turn at 45° or more, the inside pedal comes very close to the track surface. A higher bottom bracket provides the necessary clearance to keep pedaling through the banking without the pedal hitting the surface, which would cause an immediate crash. This is a safety-critical design feature unique to track bikes.