The feasibility of automatic on-board weighing systems in the South African sugarcane transport industry.
Pletts, T. R.
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Sugarcane hauliers in South Africa have high variations in vehicle payloads, which influence both transport economics and the legitimacy of their operations. Increasing economic pressure due to declining sugar prices and ever increasing fuel prices has invoked interest to improve vehicle utilisation and reduce costs, while complying with the local traffic legislation. On-board weighing technologies, such as on-board load cells, could assist operators to control their payloads more accurately and hence reduce the frequency of both over and under loaded consignments. In this study, an investigation is conducted to evaluate the feasibility of on-board weighing systems in the South African sugarcane transport industry. An overview of on-board weighing systems is presented. The overview gives insight into the technical composition of an on-board weighing system as well as presenting various benefits and drawbacks that are associated with an on-board weighing system. Earlier studies conducted on the use of on-board weighing systems are scrutinised and evaluated and it is concluded from these that vehicle utilisation could be improved, while concurrently reducing the overloading of vehicles. Field research was conducted to evaluate the accuracy and consistency of on-board weighing systems currently being utilised in the sugarcane transport industry as well as to determine the critical factors that influence the effectiveness of the system while assessing if overloading of vehicles was reduced when on-board weighing systems were employed. It was concluded that the systems evaluated were reasonably accurate with mean error being 0.4 tons. The consistency of the systems was good with 75% of all measurement being within 0.5 tons of each other. The critical factors determining the effectiveness of the on-board weighing systems were established as being management of the system as well as cane variety and quality. Overloading was reduced by 9% in one field evaluation and 5% in another. Further reduction can be realised through tighter management of the on-board weighing systems. An economic evaluation of an on-board weighing system was performed using the capital budget method. This method was used to determine the pay off period required to realise the investment into an on-board weighing system for scenarios where the payload is increased by 2, 3 and 4 tons and transport lead distance is 20, 40, 60, 80, and 100 km. The shortest pay off period occurred when the lead distance was 60 km and the time was 1, 2 and 3 years for payload increases of 2, 3 and 4 tons respectively. For lead distances of 40, 60 and 80 km the investment is worthwhile and considerable returns in investment can be realised, however, for the other lead distances the pay off period could be deemed to be too long. From the observation made during the field evaluation together with the literature studied, guidelines for the use of on-board weighing systems under various transport scenarios were formulated and are presented in chapter six.