Crianlarich Junction [CandO] had an elaborate layout. The Callander and Oban Railway was doubled from west of the junction through the junction and further east, and the West Highland Railway was also double on approach to the junction.
The junction was thus a double track junction. In addition, there were exchange sidings. This box controlled the west end of the layout, the east box being location at the point of junction. The junction and line up to the West Highland Railway were built by that company.
This additional loop on the Callander line allowed the loop at Crianlarich Lower to close in 1921, the down line (village side of station) line being retained.
The line east to Callander (Dreadnought) closed in 1965 due to the Glen Ogle Rockfall. The two boxes at the junction survived until 1967.