I think that may have just been poorly communicated. The way I heard it explained, it wasn’t a cap, but more like a standard allowance. It really sounds like that time will be extended for delays. My contract has a similar provision if I’m expected to start or end my shift away from my usual workplace, I get compensated for a predetermined amount of travel time instead of the actual time, although if I prove a major delay that’s out of my control I also get paid for that time.