The project involves the rehabilitation of the tunnels, updating of electrical system, tunnel lighting, tunnel control system, over-height truck detection system, ventilation systems, structural repairs to walls and ceilings, installation of life safety s
A project headed by the Pennsylvania Department of Transportation (PennDOT) to rehabilitate the Squirrel Hill Tunnels in Pittsburgh, Pa., is currently running ahead of schedule.
The contract, valued at $49.5 million, was awarded to Walsh Construction Company, Canonsburg, Pa. The superintendent on site is Tom Beckowitz. Work began in the spring of 2012 and is scheduled for completion by the summer of 2014.
According to Steve Cowan, press officer of the PennDOT’s Engineering District 11-01, the project involves the rehabilitation of the tunnels, updating of electrical system, tunnel lighting, tunnel control system, over-height truck detection system, ventilation systems, structural repairs to walls and ceilings, installation of life safety systems, expansion, dam replacement and bridge repair.
Cowan noted that working under traffic with lane restrictions has presented a challenge. The average daily traffic is 101,635 vehicles.
Another difficulty has been completing the work required with limited working times on nights and weekends.
“The Squirrel Hill Tunnel Rehabilitation project is not your typical roadway or bridge project,” Cowan said. “The project includes the installation of a state-of-the-art lighting and electrical system, safety systems, and a ventilation and tunnel operating system including over-height truck detection and installation of ceramic tile not normally found in roadway or bridge rehabilitation projects.”
According to Cowan, work will include the placement of 33,392 sq. ft. (3,102 sq m) of ceramic tile and the removal of 7,066 cu. yds. (5,402 cu m) of tunnel ceiling.
Major subcontractors include Sargent Electric Company, Pittsburgh; Independence Excavating Inc., Independence, Ohio; Concrete Restoration Specialist LLC, Sharon Center, Ohio; Massaro Industries Inc., Oakmont, Pa.; and Lane Construction Corp., Chantilly, Va.
Equipment used on the job includes personnel lifts and platform trucks and demolition equipment such as Caterpillar excavators with specialized concrete breakers, and shotcrete equipment.
The tunnel is 4,225 ft. (1,288 m) long, and consists of two 12-ft. (3.6 m) lanes in each direction. The existing vertical clearance is 13 ft. 6 in. (4.1 m), and the new westbound clearance will be 15 ft. 6 in. (4.7 m), while the new eastbound clearance will be 14 ft. 9 in. (4.5 m).
The tunnel first opened to traffic on June 5, 1953, and its last rehabilitation took place in 1983.
Work on the original tunnel began in 1946, and the tunnel completed the last link in the first 8 mi. (12.8 km) section of the Parkway East (S.R. 0376). It passes through Squirrel Hill in Pittsburgh, and consists of two twin arch-shaped reinforced concrete bores that are 4,225 ft. long and approximately 29 ft. 4 in. (8.9 m) wide. The tunnel is segmented longitudinally by expansion joints which occur approximately every 50 ft. 4 in. (15 m), with some variation at the entrance and exit. The walls are approximately 1 ft. 9 in. (.5 m) thick, and extend 12 ft. above the top of barrier to the intersection with the roof arch. The roof arch is three feet thick with an inside radius of 19 ft. 3 in. (5.8 m).
Additionally, a 6 in. (15.2 cm) thick, cast-in-place concrete ceiling separates the arch from the traveled lanes of the tunnel bores to form a plenum that provides ventilation for the tunnel. This ceiling was constructed 14 ft. 2 in. (4.3 m) above the roadway at its centerline. The ceiling is supported by steel hangers at the tunnel centerline., and it contains rectangular openings of varying dimensions which allow circulation of exhaust and fresh air in the tunnels. In addition to providing ventilation, the plenum carries conduits to power the cellular phone equipment.
Both roadway barriers in each bore were retrofitted in 1980 with 2 ft. (.6 m) concrete barriers and walkways for the entire length of the tunnel. The original roadway also was replaced with cement concrete pavement at the entrances and bituminous overlays through the remaining portion during the 1980 rehabilitation.