Surveying roads and bridges used to take weeks of on-the-ground work, but now it is as easy as going for a drive.
"We can do in a matter of hours or a day what would take months with traditional survey," says Paul DiGiacobbe, associate vice president at Kansas City, Mo.-based engineering firm HNTB Corp., which is experimenting with lasers and other scanning technologies to build new business.
One such technology—based on lidar, or light detection and ranging—is not exactly new. For years, engineers have used laser scanners, mounted on tripods or aircraft, to bounce light off objects to measure landscapes, structures and utilities.
However, recent advancements are now allowing surveyors to put the equipment on a passenger car, boat, railroad car or ATV, enabling faster data acquisition while driving along the work zone.
The equipment, which sends out up to 500,000 pulses of light per second, is not cheap, costing up to $750,000 per unit or renting for $6,000 per mile for a typical scan. But the payoff is more efficient construction and maintenance of civil infrastructure.
"A lot of us have to be lean and mean with our manpower," explains Daina Morgan, product manager for Optech Inc., a Canadian lidar equipment supplier. "This is a tool [that can help] a lot of surveying companies, mapping companies and engineering firms to be able to compete."
Morgan cites as one example Optech's new Lynx Mobile Mapper, a lidar device that is often mounted atop a sport-utility vehicle. The sensors sit on a mounting plate measuring approximately six feet long, two feet wide and 1.5 feet tall.
The roof rack also carries a global positioning sensor, for location mapping, and a vehicle measurement indicator, which mounts in a wheel hub. It compensates for location when GPS is not available, such as inside a tunnel.
Operating at 500 kHz, the sensors can map roads, bridges and railroads—even "street furniture," such as curbs, signs and lights—while the vehicle drives at posted highway speeds.
"There are quite a few engineering firms purchasing this kind of hardware," Morgan says. "Our top client is a surveying company."
HNTB, a civil design firm, hopes to use mobile lidar to drive new business in building information modeling.
"The application of that sensor on a mobile platform completely changes the game from a survey for typical design to a survey for construction management," DiGiacobbe explains. Mobile lidar sensors can scan at a distance of more than 300 ft within a half-inch of accuracy, he notes.
