Civil Engineering October 2021 | Vol 29 No 9

50 October 2021 Civil Engineering crops have been handled since its inception two years ago. It would be a matter of much regret if this innovation were ousted by the narrow-gauge, which does not fulfil the same object. FROM SINGLEWOOD TO ZEBEDIELA This narrative of the roadrail experi- ment would be incomplete without brief consideration of a parallel development that had a direct bearing on the eventual fate of the Singlewood narrow-gauge line. About 30 miles to the east of Singlewood, the business tycoon Isidore Schlesinger bought a large tract of land in 1917 to establish the Zebediela Citrus Estate. Development of the estate began immediately with bush-clearing projects, dam building and soil preparation to allow the planting of the first citrus trees in 1918. Planting continued unabated and 500 000 trees had been planted by 1925 with the first already bearing fruit. The projected production was 1 200 tonnes/ year in 1926, 10 000 tonnes/year by 1929, eventually peaking at 50 000 tonnes/year. For some unknown reason, SAR&H seemed to be completely unaware of, or chose to ignore this development when the Singlewood line was planned and built. The projected volumes of freight from Zebediela Citrus Estate would completely overwhelm the capacity of the roadrail line. SAR&H could only meet the increased load by either extending the narrow-gauge line from Singlewood to Zebediela and retain the Lawley locomotives (which were already in service), or tear up the narrow-gauge line and replace it with a line of standard gauge all the way from Naboomspruit to Zebediela. The elimination of transshipping at Naboomspruit was the main reason why the Railway Board subsequently presented a proposal to Parliament in 1925 for a new 84 km line at standard gauge from Naboomspruit to Zebediela. Parliament concurred, construction started in January 1927 and the line was officially opened on 17 October 1927, just in time for the citrus traffic which grew exponentially thereafter. By July 1930 up to 162 wagons of citrus were transported in a single day. At the height of the season, two or even three special citrus trains had to be run daily between Zebediela and Pretoria. Figure 13 shows one of the Lawley locomotives (which was sold to the Zebediela Citrus Estate after the new line was opened) collecting crates from an orchard. REFLECTION The abrupt end of the roadrail experi- ment, without the sanction of Parliament, had to be explained. The Railways and Harbours Board reported to Parliament that: … the roadrail has, up to now, not come up to expectations owing to the difficulties in working the line. Considerable trouble has been experienced with the tractors as well as with the road bed and the limited speed of the tractors … [which] to a large extent nullifies the greater tractive force of the roadrail engine. General Manager Hoy gave a more guarded, but essentially the same, version: … it cannot be claimed that the experiment proved altogether an unqualified success. Although it is only fair to mention that the difficul- ties which presented themselves were not so much due to the system as a system of transport, but rather to trouble experienced with the tractors as well as with the road bed and the limited speed of the tractors, which on an average did not exceed eight miles an hour. Twenty years later, when a more sober assessment would be expected, two well-known railway engineers (one was a retired SAR chief mechanical engineer) dismissed the roadrail concept as techni- cally inherently flawed, referring without further explanation that faulty assump- tions had been made regarding road and rail traction. This is a most surprising conclusion – it not only flew in the face of the evidence available, but was the first mention of issues that had never been raised or disputed before: The tractive efforts per ton of axle load assumed by the protagonists of the [roadrail] system were unduly optimistic regarding road traction and the reverse regarding rail trac- tion. This system of combined road and rail appears to have had the limitations of both and advantages of neither. It will be recalled that Dutton’s raison d’être for the roadrail concept was to provide an initial pioneer railway to emerging farming communities in a cheap enough way to pay for itself. In his opinion, the roadrail experiment proved everything that was promised – low cost, adequate traction, the ability to navigate Figure 13 A Lawley locomotive collecting orange crates in 1928 (Credit: THL N60051)