In the wee hours one night in July, a Greyhound bus heading to St. Louis turned onto an exit ramp leading to a rest area in Southern Illinois and hit three parked tractor-trailers, smashing its front, crumpling its roof and ripping off part of its side.

Three passengers were killed. The tractor-trailers were parked along the ramp’s shoulder, a common sight on the nation’s highways.

“It’s scary because it can happen in the blink of an eye,” said Carmen Anderson, 64, a South Dakota-based truck driver for America’s Service Line, who recently had to park on an off-ramp in North Carolina after not being able to find parking at rest areas or truck stops.

The accident in Illinois highlighted a widespread complaint among the nation’s truckers: Parking spots for commercial trucks are hard to come by.