The traditional process sends surveyors into the tunnel every so often, usually during a lunch break, says Fernando. "With the new system, we get readings in moments, and it only takes about 30 minutes to move the device down the tunnel and set it up again," he says. While the total station can read the targets up to 1,500 m away, the device must stay within 200 m because the TBM's trailing gantry system and dirt carts get in the way.

Fernando's team has always tracked how much downtime surveying costs his tunneling operations. With VLTB, Lu and Fernando agree that 10% of total construction time easily could be saved.

While Lu is working with TECTERRA to find collaborators interested in making the system commercially available, the city of Edmonton is planning to use VLTB on an upcoming tunneling job. By that time, VLTB may be out of the testing phase and on the market for surveying consultants.