Jeff Blackburn, the driver of a CleanScapes trash truck in Seattle, became a YouTube celebrity this summer when he was videotaped saving a baby inside a runaway carriage zooming down a steep street. Blackburn sped along with the carriage, honking his horn to warn cross traffic as the carriage zipped through intersections, until it came to rest safely at the bottom of the hill. His actions were captured by a cab camera installed by Blackburn's employer to monitor driving.

Truck fleet operators are increasingly adopting cab cam systems to cut down on accidents, liability claims, worker downtime and reputational risk. One such company is $13.4 billion Waste Management, which has thousands of vehicles operating nationwide.

DriveCam, one of the two largest vendors of in-cab video monitor systems along with SmartDrive Systems, says that after a six-month trial, Waste Management ordered two cams—a driver monitor and an outward-looking cam—for all its trucks by yearend. "They were so excited about the success of the trial that they wanted it fleetwide right away," says DriveCam spokesman Eric Cohen.