Why does it take large dump trucks (and pretty new ones at that)? Those things guzzle diesel. Couldn't the same purpose be served by a pickup truck with an arrow sign and flashing lights following the paint truck?
Because they'd have to buy things like these 'traffic attentuators' to safeguard their employees in the paint truck. The flashing signs don't save you from some idiot tearing down the breakdown lane because s/he's late for work and doesn't know what the holdup is.
Or, clearly the dump truck is cheaper </sarcasm>.
*Although the dump truck actually may be cheaper because it can be used for other things as well, like doing tar snakes/pothole repair/other hauling. Three is excessive.
About the only power sources that don't have the potential to catch fire are wind and solar. Solar panels do have a good bit of cadmium, usually.
When wind power fails, it fails spectacularly. Occasionally they catch fire too
The moon is made of green cheese. -- John Heywood