Where may a placarded hazmat vehicle be parked overnight?

Parking a placarded hazmat vehicle is heavily regulated to limit consequences if the cargo leaks or ignites. The rules: do not park within 5 feet of the traveled portion of a highway; do not park within 300 feet of a place where there is an open fire or where people are likely to congregate (theatres, malls, schools, churches) — with exceptions for very brief loading/unloading. The vehicle must be attended at all times in some cases (Class 1 explosives, for instance) unless parked in a 'safe haven' specifically designated for hazmat overnight parking. Some materials require driver presence within sight and sound of the vehicle. Different rules apply to different classes; consult Section 9 of the FMCSA manual and 49 CFR Part 397 for specifics.