Ham's '48: Twinkle Twinkle Little Truck ...

[51 CJ3]

Surge brakes work well for stopping and downhill control with no mods required to the towing vehicle. They don’t work as well as electric brakes for holding pointed uphill nor do they give an operator direct control over the brakes.

I looked up the story on the accident. It is a modern truck so it does make a person wonder why the brakes seem to have failed. One of the mods may have been rushed and/or incomplete to make the parade. It was a youngster driving so probably not enough experience driving to think of the parking brake, killing the engine or putting it in neutral. Very sad event for all involved.