The scene alone was enough to back up traffic for miles: a mangled guardrail fence on the Southwest 18th Street near Boca Raton overpass above Florida’s Turnpike and a crumpled vehicle in the southbound lanes below, its driver dead at the wheel.

And still, it could have been much, much worse.

Authorities closed the turnpike’s southbound lanes between Southwest 18th Street and Glades Road for more than four hours Sunday after the vehicle plowed through the overpass fence and plummeted onto the highway, somehow missing a steady stream of noon traffic, Palm Beach County sheriff’s spokesman Eric Davis said. The crash led to no other accidents.

Sheriff’s investigators treated the event as a crime scene, rerouting traffic at Glades Road while they collected evidence, Davis said. The sheriff’s office said information from the driver’s family indicated he had talked about committing suicide.

The wreck snarled traffic for miles in both directions of Florida’s Turnpike until the southbound lanes reopened at 4:30 p.m. Authorities rerouted traffic as they worked the scene, vehicles backing up almost to Atlantic Avenue on the closed southbound side, according to the Florida Highway Patrol. Eastbound lanes of the Southwest 18th Street overpass at Boca Rio Road also were closed, and drivers headed in the other direction remained in awe of the scene.

Even drivers in the turnpike’s northbound lanes, which remained open during the investigation, could not look away.

Onlooker delays slowed the northbound traffic for about six miles, from the accident site to the Sawgrass Expressway in northern Broward County. Some cars pulled off to the side of the road, waiting for traffic to move again. Others headed to side streets or Interstate 95 to get around the wreck.

Authorities were still investigating late Sunday and had not released the name of the driver or more information about the crash.