Pittsburgh’s Port Authority plans to invest more than $30 million to upgrade infrastructure in portions of its 26.2-mile light rail system.

The authority’s governing board is expected to endorse a recommendation by the agency’s Performance Oversight Committee to award a $19.3 million contract to Golden Triangle Construction Co. to rehabilitate deteriorating 30-year-old concrete plinths in the light rail tunnel beneath downtown Pittsburgh. The six-phase project, which also includes track replacement is scheduled to be completed over 30 months. It follows the recently completed installation of new LED lighting, including more than 16,000 ft of conduit and wiring.

A separate $10.8 million project will upgrade 18 high platform stations along three lines in Pittsburgh’s southern suburbs.

General contractor P.J. Dick will handle concrete and masonry repairs, improve access for disabled passengers, replace fiberglass panels and install metal railings and LED light poles. Under a separate contract, Merit Electrical Group Inc. will install fixtures and wiring for the stations’ new fare collection booths.

Also on the Port Authority Board’s Sept. 24 agenda are consideration of recommendations laid out in a 25-year, $4 billion regional transit improvement plan released last week. Projects include phased expansion of both the light rail system and the Martin Luther King Jr. East Busway, and establishment of a new transportation corridor linking Pittsburgh’s Strip District with neighborhoods to the south.