"Selectric" frogs were used in several places on the Adelaide trolleybus system, for example being used at the Glenside short working on the Linden Park line and worked reasonably well there. (The attached picture by Mike Church shows Leyland "Canton" 488 making the turn around the traffic island as its poles approach the offset sensors in the overhead). Another was at the entrance to Hackney South depot. Most of Adelaide's frogs were pulled manually by the conductor who then chased his bus and climbed on after it had passed through the frog. A "Selectric" frog was installed initially after the tramway conversions at the end of Dequetteville Terrace where the Burnside and Erindale trolleybuses diverged up Kensington Road from the Linden Park trolleybuses proceeding across to Victoria Avenue (now Fullarton Road). The intersection was very wide, had a great deal of weaving and ill-disciplined peak-hour motor traffic, there was little divergence between the two paths. Despite coloured marks on the road to guide bus operators, dewirements were very frequent. Eventually the whole intersection collapsed after a dewirement in the evening peak and the automatic frog was replaced by a manual frog about 100 metres earlier with the services approaching the intersection using two parallel sets of wires.

John Radcliffe