Central Station approach, Sydney, Australia

New South Wales suburban and outer-suburban trains are double-deckers, built to the generous Australian loading-gauge, based on the pre-war French prototype, the Voiture État à deux étages.

The doorways at the end of each carriage lead to a mezzanine level, which is used by passengers with pushchairs or wheeled luggage, and stairs lead up and down to the two central compartments.

It’s an odd sensation to sit so high above rail-level on the top deck, and even odder to sit below-decks with the platform edge skimming the windows.

Double-deck carriages twenty metres long carry nearly 50% more passengers than single-deck rolling stock of equivalent length, saving the huge expense of lengthening station platforms.

To allow for the low-slung centre section, designers had to move as much electrical and mechanical equipment as possible on to the roof above the entrances.

The first of double-deck trailer cars were introduced in 1964, followed by double-deck motor cars four years later.  Interurban double-deck trains, with an additional burden of air-conditioning units, followed in 1970.

Travelling to outer Sydney, with little idea of direction let alone distance, I was anxious to know what level of creature comforts my train would provide.

I quizzed the travel-information officer about on-board lavatories in my best Pommie accent.  He replied, “You’re in the wrong country mate.”

Ask a silly question.