When I used to run Tristar engines in BAH for Gulf Air, we didn't have a run bay but parked the aircraft on the apron, and blocked off the road behind with signs and cones. One day we blew over a car load of airport police. The reason was, they saw the sign but because they were police they decided it didn't apply to them. Nearly wrote off a Land Rover, and they didn't look too good either. Their boss gave them a telling off.
One day the wind was wrong and the tower let us park on the taxiway. The VASI's disappeared over the runway.
There is a lot of power in a jet blast.