Terrametrix was contracted by Caltrans - the California Department of Transportation - to undertake detailed surveys of bridges throughout the state. Driving the need were revised standards of the Federal Highway Administration bridge inspection programme. These standards required the longitude and latitude location of each bridge to be established as well as a measurement of minimum clearance, both horizontally and vertically. Caltrans specifically requested documentation at highway speeds, transparent to the travelling public, without impeding traffic.
Terrametrix is collecting the measurements using vehicle-mounted lasers. By using the StreetMapper system, Terremetrix is able to capture as-built data of existing infrastructure at a fraction of the time and cost of traditional survey methods. “The StreetMapper technology offers proven, survey grade accuracies with final positional accuracies of better than 0.03’ [9mm] with appropriate survey control,” said Terrametrix president Michael Frecks. “Relative positional accuracies of better than 0.02’[6mm] in raw data make StreetMapper a very useful tool for bridge height surveys.”
Working with Allpoint Systems, Terrametrix developed a workflow to process the 531 terabytes of data collected by the StreetMapper system. “The combination of being able to collect data at normal traffic speeds and the automated extraction addresses traditional unsafe data collection methods, both for the surveyor and the travelling public, and time-consuming data extraction,” said Frecks. “Using this methodology we are able to deliver results in one day instead of one month completing survey projects in a tenth of the time.”
StreetMapper was developed by UK-based 3D Laser Mapping in conjunction with German based guidance and navigation specialist IGI.
