The tunnel is long, and is approached on either side by climbs at the
ruling grade of 1 in 40 (2.5%). The
single track tunnel, the oldest of its type in use in New South Wales, By June 1876 the tunnel was enlarged and brick lined with track laid. The contractors engine made it through the tunnel by July 1876. The line to Quirindi was opened in August 1877.
Fumes The Ardglen Tunnel is at the summit of
ruling grades, and because of its narrow profile, it created fume problems during steam days. Larger locomotives, such as the
60-class Garratt, were either prohibited or limited in load. Fortunately most heavy trains went through the tunnel in the downhill direction, towards
Sydney and
Newcastle. Curve and Gradient chart shows the tunnel as being level.Sydney and Newcastle are to the left.
Proposed deviations To cope with considerably increased coal traffic from north of the tunnel from 2010 and beyond, various deviations are proposed. These deviations can either keep the existing summit tunnel, or bore a much longer tunnel at a lower elevation. The deviations that keep the existing tunnel increase the length of the line so as to ease the gradient to 1 in 80 which is the ruling gradient on the rest of the line to the port. The existing line would be retained for empty trains going the other way, so forming
double track.
Stations The stations on either side of Ardglen Tunnel from the south are: •
Murrurundi – medium length
crossing loop and start of ruling grades. Had a locomotive depot for
bank engines in steam days •
Pangela – closed short crossing loop on ruling gradient • Ardglen Tunnel – summit •
Ardglen – medium length crossing loop and railway station, being further lengthened in 2010 •
Kankool – short crossing loop on ruling gradient •
Willow Tree – medium length crossing loop and railway station and end of ruling grades == Heritage listing ==