Analytical Methods to Estimate Railway Capacity A Case study to apply on the Addis Ababa Light Rail Transit Project (AA -LRT)

Public mass transportation systems have become an important part of major economic activities in developing cities. The initial high construction cost of urban rail transportation calls for the efficient utilization of the existing infrastructure and estimation of its maximum capacity. A reliable estimation of railway capacity is a basic condition for allocation of railway resources and has a vital importance in evaluation of existing railway infrastructure. Therefore, it is necessary to develop procedures that reliably estimate the railway capacity using data typically available to planners. This thesis studies method that can be applicable in both planning and detailed design stage in Ethiopian condition depending on the available data .An overview concept of railway capacity and the main parameters affecting railway capacity are presented. A simulation method is a widely used technique in railway planning and operation to generate realistic estimates. Analytical methods of estimation railway capacity provide firsthand information about the capacity at early planning stage when most of the factors shaping up the railway capacity are not known and has also provide a reliable result in detailed design stage when it is applied to a simple rail network system like AALRT. In the detailed design report of AALRT, the procedure used in determination of the capacity is not described and only the output results are provided. Therefore, developed methodologies to analyze, improve and control railway capacity utilization are needed for Ethiopian condition. This thesis presents how to determine the number of trains required for a given passenger volume and headway using analytical method and mainly focuses on methods to calculate the main parameters affecting the capacity of Light rail transit system. Methodologies that describe the procedures to follow in estimation and analysis of railway capacity are developed. Two approaches of estimating railway capacity are presented. The first approach is an economical way of estimating railway capacity based on peak hour passenger volume and the second approach is the estimation of achievable capacity using the maximum throughput of the railway line. The combinations of the two approaches enable planners or designers to estimate the capacity of railway at different values of headway and train controlling systems. Using these two approaches, the proposed capacity of AALRT is evaluated and its maximum achievable capacity is estimated. The computational results at the end shows that the proposed headway of AALRT can be improved by reducing total round trip time of the trains and the proposed excess number of trains can be used to reduce the headway of the operation.