High Definition Survey for Dallas North Tollway Widening

PBS&J surveyor positions high-definition survey (HDS) equipment on tollway shoulder.

The Dallas North Tollway (DNT) processes more than 350,000 toll transactions daily. So when the North Texas Tollway Authority (NTTA) was ready to embark on a tollway widening project, they were determined to do so without compromising their record of safety and high quality customer service.

It seemed as if the toll agency could be faced with a complex and potentially dangerous data collection process—even before design concepts for the widening of the DNT could take shape. But PBS&J, project engineer for the assignment approached the NTTA about using high definition surveying (HDS) to get the job done. A non-intrusive means of rapidly collecting detailed and accurate as-built data, HDS enables the user to capture existing conditions data on heavily traveled roadways without impeding traffic flow or sending survey personnel into harm’s way.

Using 3D laser scanners in place of traditional survey tools, PBS&J collected vast amounts of data related to pavement, barrier walls, signs, lighting, aboveground utilities, and toll plazas in a matter of hours. The digital images generated were used as the basis for project design decisions, and provided an historical, digital, 3D record of the site. The laser scans were registered together in the field each day and the final point cloud was converted into MicroStation for use in creating a digital terrain map (DTM) and a topographic drawing.

As a result of this innovative approach, the project was recognized in early 2005 with a gold medal from the Texas Council of Engineering Companies (TCEC).