...The semi was headed west when its raised bed slammed into the overhead sign near mile marker 200 as it approached the I-64/I-295 split.
Virginia State Police said the crash happened shortly after 9:30 a.m.
"The cab continued on and then stopped, obviously, because it had separated from the bed of the tractor-trailer," Matt Demlein, a spokesperson for Virginia State Police, said. "We're still investigating as to what led up to it actually hitting the sign. It was empty at the time."
Troopers do not know why the bed was raised or how long it was up before the crash. But officials said the truck had stopped at a weigh station about a mile earlier, which is equipped with cameras...
You need to be able to move while dumping stuff. A beeping noise during normal operations would be so annoying, people would just figure out how to disable it.
An alarm above a certain speed would make sense, though.