The Dargans Deviation was a section of the original Main Western railway line over the Blue Mountains in New South Wales, Australia.
The deviation started construction around July 1896 due to a sudden rise in traffic along the Western Line.
It was longer than the original alignment, but it eased the grades to 1 in 60 and stretched three miles from Newnes Junction to Clarence.
During construction, when the line rejoined the original alignment at Clarence, a number of changes had to be made.
The construction was initially planned to take six months but due to a number of delays, including one incident where among other things a charge exploded prematurely, the line wasn't officially opened until April 1897.