PennDOT closed one lane of the Liberty Tunnel Wednesday, but this time it wasn’t for construction.
As part of a program for contractors and highway officials from more than a half dozen states, several private companies demonstrated equipment that can be used to assess the condition of a tunnel without causing damage. The demonstration was part of the Strategic Highway Research Program, administered by the Federal Highway Administration and the American Association of State Highway and Transportation Officials to find innovative, less expensive ways to build and repair roads and bridges.
The most sophisticated, by Penetradar Corp. of Niagara Falls, N.Y., involved a van that drives through a tunnel, sending out radar and taking thermal photos to check its condition. The radar provides a 180-degree assessment of the entire tunnel in a few hours, finding weak spots and water leaks, among other problems.
That type of inspection usually requires closing a tunnel while a team does manual assessments that can take weeks and often involve drilling into the surface.
Other demonstrations included a $2,000 electronic hammer used to tap the surface and record the resultant sound waves to show the condition beneath the surface.
Lou Ruzzi, PennDOT’s district bridge engineer, said the Penetradar inspection is more expensive than the usual method — about $100,000 for Penetradar to inspect one lane each in the Liberty and Armstrong tunnels compared to $51,000. But the speed of the electronic system could make it more attractive in the future, he said.
The department will keep the results from inspections this week of both the Liberty and Armstrong tunnels for comparison purposes when they are inspected again in a few years. PennDOT completed rehabilitation of the Squirrel Hill Tunnel in 2014, the Fort Pitt Tunnel ceiling removal project is nearly done and the Liberty Tunnel rehab is in its final phase.
Ed Blazina: eblazina@post-gazette.com or 412-263-1470.
First Published: September 15, 2016, 1:24 a.m.
