Throughout the 2000s, state officials attempted to implement plans to replace the tunnel, citing the westbound tube's age.

The original Allegheny Mountain Tunnel was built in the late 19th century for the South Pennsylvania Railroad, which was never completed.

[citation needed] The current westbound tunnel was built in 1939 as part of the original construction for the highway.

[2] The former South Pennsylvania Railroad tunnel was considered but was again rejected because of its poor condition.

On December 24, 2014, the PTC announced it was going forward with plans to replace the Allegheny Mountain Tunnel.

[8] In 2020, following analysis of several design alternatives, the Pennsylvania Turnpike Commission opted for a new road only alignment to the south of the tunnels, which – at $332 million for the versus $628 million for a replacement tunnel – is the least expensive and environmentally disruptive of the alternatives.

As part of the project, several sharp curves to the east of the tunnel will be redesigned to meet current standards.