Civil Engineering August 2021 | Vol 29 No 7

Civil Engineering August 2021 49 demonstrate that the 1:20 grade sug- gested for full scale roadrail would pose no problem at all; see Figure 9. Q Q The model tractor could climb over obstacles in the wheelway of up to 450 mm (full scale) without the “slightest tendency for the bogies to become derailed”. Q Q A wheelway external to the rails, as used at Canada Junction, would make roadrail with its wider footprint more expensive in mountainous country where many long cuttings and em- bankments are normally required. If necessary, this could be eliminated by a tractor fitted with a single driving wheel running between the rails, which worked just as well; see Figure 10. INTERNATIONAL EXPOSURE Dutton registered his first patent for the roadrail concept in England during 1917. In October 1918, after the tests at Canada Junction, Dutton offered the patent rights to the SAR&H. Surprisingly, his offer was not accepted, “presumably on the grounds that the system would be of little value to the Department”. He proceeded to register a series of roadrail-related patents in England and the United States. His pat- ents in the United States were dated June 1919, May 1922 and November 1925. During 1920, Dutton visited England to commercialise his invention and joined forces with General R.S. Stronach to form the company Roadrail Loco-Tractors Ltd (Stronach-Dutton patents) in October 1920. It was taken over only four months later by a new company, Roadrails Ltd. Stronach probably had some engineering background, for he was England’s director of roads and bridges during World War I. He served 15 years earlier in the Anglo- Boer War, as did Frank Dutton. It is quite possible, as yet unconfirmed, that the co- operation between Dutton and Stronach went back to that time. Stronach (the deputy chairman of Roadrails Ltd) managed to garner the sup- port of several influential figures for the “Stronach-Dutton Road-Rail” invention as it was labelled in England. The company launched a vigorous campaign to promote the system internationally and attracted attention from numerous countries. With varying success, attempts were made to establish roadrail in Australia, Colombia, England, India, Morocco, Scotland, Spain and Uganda. Notable Figure 8 Dutton with his double-bogie tractor model (Credit: SAR&H Magazine, August 1923, page 827) Figure 9 Experiment with sharp changes in gradient (Credit: THL_18_012) Figure 10 Model tractor with single central driving wheel (Credit: SAR&H Magazine, July 1922, page 663)