The Whitehall Tunnel in Allegheny County, Pennsylvania

Allegheny County, Pennsylvania

Allegheny County is a county in the southwestern part of the U.S. state of Pennsylvania. As of the 2010 census, the population was 1,223,348; making it the second most populous county in Pennsylvania, following Philadelphia County. The county seat is Pittsburgh...

 was originally built by the B&O Railroad in 1899 as a double-track tunnel. The tunnel was completed in 1900.
It was part of the Baltimore and Ohio Short Line Railroad, and allowed the B&O to bypass its former route into Pittsburgh along the Pittsburgh Southern

Pittsburgh Southern Railway

The Pittsburgh Southern Railway was a narrow gauge railroad in Pennsylvania. It was formed in March 1879 by the merger of the Pittsburgh Southern Railroad , Pittsburgh Railroad, and Washington Railroad...

 and Little Saw Mill Run Railroad

Little Saw Mill Run Railroad

The Little Saw Mill Run Railroad was a standard gauge coal railroad in Allegheny County, Pennsylvania. It was incorporated July 23, 1850, and opened in April 1853. Originally, it was owned by the Harmony Society, and ran from Temperanceville, Pennsylvania on the Ohio River to Banksville,...

. One worker, Antonio De Bono, was killed during its construction.
It is currently a single-track tunnel, owned by CSX. The tunnel is approached from Glenwood in the south, up a steep grade along the Streets Run

Streets Run

Streets Run is a tributary of the Monongahela River in Allegheny County, Pennsylvania. This urban stream drains portions of the communities of Pittsburgh, Baldwin, Brentwood, West Mifflin and Whitehall, an area of about ten square miles.-Colonial history:...

 valley to the northern end of the tunnel. The line continues from the southern end to Bruceton, Pennsylvania

Bruceton, Pennsylvania

Bruceton is an unincorporated community in Allegheny County, Pennsylvania, United States. It is the home of an experimental mine of the U.S. Bureau of Mines, which originally opened in 1910. It is also the home of the Pittsburgh Safety and Health Technology Center. The Pittsburgh and West...

.

Dimensions:
28 ft (8.5 m) at base;
30 ft (9.1 m) at spring line;
23 ft (7 m) from top of rail to top of arch rise

Engineer: W. T. Manning; Bennet & Talbot, subcontractor, 1901-02