To augment the exisiting 32-lever mechanical frame, a miniature-lever console of 10 levers was introduced at Hawkesbury River in 1940 to control new colour light signals installed on the main lines within station limits.
In 1954 the console was enlarged to 40 levers to accompany the introduction of motor-worked points and banner shunting signals.
The interlocking arrangements at Hawkesbury River were complex. All interlocking between electrically and mechanically operated signals and points was implemented using electric circuits.
There was no room in the platform signal box to house this circuitry and make it easily accessible for maintenance. As a result, an electric-interlocking house was constructed on the platform to the immediate south of the signal box.
Elevated signal channels ran between the signal box and the interlocking house and between the interlocking house and the outer side of the down refuge, from where trackside channeling ran to the signals and points.