[2] The tunnel is cut through a hill in Phoenixville, Pennsylvania, United States.

These shafts were spaced at 100-foot (30 m) intervals to correct errors in the tunnel alignment.

[4] Noted local miner, geologist and paleontologist Charles M. Wheatley examined the rock excavated from the tunnel and identified many previously unknown fossilized species, some of which now bear his name.

The widening of the tunnel was the first project to employ electric detonation of multiple explosive charges.

[6] The northern end of the tunnel is high on a steep bank of the Schuylkill River so the rail line makes a dramatic transition from tunnel to bridge.