School bus guidance defines a danger zone around the bus. How far does it extend, and which part of it is most dangerous?

Explanation

The danger zone reaches as far as 30 feet ahead of the bumper, and the closest 10 feet of that is the worst of it, with a further 10 feet out to each side and 10 feet off the back of the bus. These are the CDL manual's figures, not a federal measurement. The zone is deepest at the front because that is where children cross, and because the hood and front pillars hide the ground just beyond the bumper from the driver entirely, so a child standing there is simply not visible from the seat. The same guidance treats everything on the driver's side as dangerous whatever the measured distance, since that is the side cars come past on. The wrong options each shrink the zone and lose a real blind area in the process: flattening it to a uniform 10 feet drops both the long forward reach and the idea that any part of it is worse than the rest, swapping the 30 feet to the back assumes direct vision covers the front when the front is the one place it fails, and treating only the loading side as dangerous depends on other drivers actually stopping. 49 CFR 383.123(a)(2)(i) makes loading and unloading children, and the warning and passenger safety devices that go with it, a required knowledge area for this endorsement, but states no distance, so the geometry here is attributed to the manual.

Source: 49 CFR 383.123(a)(2)(i)