The tunnel consists of two bores that pass through Squirrel Hill in Pittsburgh, carrying two lanes of one-way traffic in each direction for Interstate 376 (Parkway East).

The tunnel consists of twin arch-shaped reinforced concrete bores that are 4,225 feet (1,288 m) long and approximately 29 ft 4 in (8.94 m) wide.

[3] With the help of Carnegie Mellon University graduate students, the tunnel has provided FM reception since May 2005; moreover, AM signals were upgraded at that time.

The plenum contained rectangular openings of varying dimensions that allowed circulation of exhaust and fresh air in the tunnels.

The original roadway was also replaced with cement concrete pavement at the entrances and bituminous overlays through the remaining portion during the 1980 rehabilitation.

The facades and exterior surfaces of the portal buildings are sandstone and brick veneer with louvered openings and block-glass windows.

Additionally, the entrance to each tunnel has traffic signals mounted overhead, which are part of the over-height truck detection system.

The Pennsylvania Department of Transportation raised the ceiling of the Squirrel Hill Tunnels to eliminate this problem and ease flow of traffic in and out of Pittsburgh.