When a railway is being upgraded, several alternative investment proposals may be considered. This thesis describes the development and use of a computerised model to investigate the combined effects of such investments for a less developed country railway.
The work focuses on the Botswana line as a case study, but could be, applied to any railway system with similar operating characteristics. It is designed to reflect the priorities of such systems, namely to have the capacity to haul traffic safely and at a low cost; with speed and frequency of service being considered less important. The model also allows for the inefficiencies in operations
found in many such railways.
The model concentrates on line rather than yards and is in
three parts; an operations model; calculations to determine line capacity and general statistics; and a cost model.
Each stage of the model involves a development from previous
theory on the subject. A train speeds model has been produced which gives results of acceptable accuracy from a simple data input. The train delay model reflects the types of delays found using both low and high, technology trains working methods. The accuracy of both the speed and delay models was tested by running them separately from the
rest of the model, using data from Botswana. Appropriate measures of capacity were developed. Cost equations were produced from information obtained from Botswana and Zimbabwe, and from general literature on the subject.
Example runs of the model were performed for illustrative
purposes, representing the main investment proposals being considered in Botswana in 1982. It was possible to perform many runs quickly and easily, and thus to obtain much more information than was available in documents produced for Botswana using conventional investment appraisal methods.