The tunnel was completed in 1877 and is owned by the Transport Asset Holding Entity, a state-owned corporation of the Government of New South Wales.

[4][5][6] The tunnel is 528 yards (483 m) long, and is approached on either side by 10-kilometre (6.2 mi) climbs at the ruling grade of 1 in 40 (2.5%).

[9] The Ardglen Tunnel is at the summit of ruling grades, and because of its narrow profile, it created fume problems during steam days.

[4] Ardglen Tunnel was listed on the New South Wales State Heritage Register on 2 April 1999 having satisfied the following criteria.

[4] The place possesses uncommon, rare or endangered aspects of the cultural or natural history of New South Wales.