Terrametrix recently completed 3 miles of tunnel data using the StreetMapper system. After simulating and testing the StreetMapper processing workflow in a real environment for more than a year, Terrametrix took the system to a project containing four tracks and catenary wires in an 8,800-foot-long environment with no GPS for 14 minutes. The final results were an RMS error of 0.04 foot. The project was part of a positive train control (PTC) project and also included a clash detection requirement.

“The tunnel tests have shown that StreetMapper can achieve better than 35 cm positional error in a 2000 m tunnel that takes about 2 minutes to drive,” said Dr. Graham Hunter, the developer of the StreetMapper system. “Most obstructions along a highway due to bridges and buildings will be equivalent to a tunnel less than 500 m; this shows that in these cases a positional error of better than 6m can be expected.” (For more details, see the “Simulated Tunnel Accuracy” Report.)