So, what could have lead to the development of intermodal traffic on railroads/roads/sea-based shipping earlier than OTL?
Italian futurism had this bizarre idea called modulism, wha if this artistic trend get a sudden application in commerce from 1929 on, in the form of a shipping cargo box (6x2.5 metres) that allows multimodal logistics?
From Conway’s ‘The Shipping Revolution’: The Modern Merchant Ship
British railway companies had experimented with containers in the 1920’s and 1930’s, but the typical construction of the times, which was wood reinforced with metal created a unit with a heavy tare weight of some three to four tons. The payload was also about four tons so that the tare to payload ratio was about 1:1. This was not good at all and railway operations of the time were in any case fragmented and unsuited to intermodal transport operations.
When change came is was from association with the developing trucking industry in the United States. The lightweight container with a ratio of 10:1 or more between lifting capacity and tare weight was developed in road transport use and transferred to sea transport in the 1950’s.
A very interesting statement is this
Building the Steam Navy, Dockyards, Technology and the Creation of the Victorian battle Fleet 1830 – 1906 by David Evans.
Page 170
Another far sighted plan, this time for containerised transport of coal to the yards, was submitted in December 1846 by the solicitors to the Bristol & Poole harbour railway, who having a floating dock at their Bristol terminus:
…by which means their iron Barges containing the Boxes with Welch Steam Coals...will be placed on the Line and conveyed without shifting, or break of gauge direct to Her Majesty’s Stores either at Gosport or Portsmouth or by means of a Pier alongside of which a Steam Ship may lie and the Coals be placed at once on board – affording thereby a continuous supply of Best Steam Coals in first-rate conditions…
They had submitted a scheme to supply 21,000 tons annually to Mr Russell, contractor for supply of coals at Southampton for the Great Western Steam Navigation Company, the P & O Steam navigation Company, and the Royal West India mail Company, and to the Engineer in chief of the last. And they had agreed to support the plan. There would be a small increase in price, but this would be compensated for by the excellent condition of the coal. This offer was not taken up.