THE STRONACH-DUTTON RAILROAD SYSTEM OF TRACTION
NGRS 234
This little-known railway system was invented around 1913 after the realisation that rails which were heavy enough to carry a locomotive were far stronger than was necessary for wagons or carriages.
The idea was that the track would be built in lighter materials with the main weight of the locomotive being carried on road wheels which ran alongside, the loco being located on the rails by small bogies.