Numerical Analysis On Dynamic Response Of Metre Gauge And Standard Gauge Ballasted Tracks

The goal of this thesis is to study train-induced dynamic responses of the metre gauge and standard gauge tracks due to train speed.A case study of a Central Railway Line in Tanzania has been used to study the dynamic responses due to different speeds and comparing the results of the two railway tracks by means of MBS and FEA software.The railway transportation in Tanzania and the rest of African countries have been characterised by narrow gauge with improper maintenance and low traffic volumes compared to other modes of transportation.Tanzania,in particular,is constructing standard gauge ballasted railway lines so that to catch up with the transport demands for capacity and speed,comparison of the narrow gauge and standard gauge is of vital importance.Different works of literature have noted that the increased speeds of contemporary railways generally enhanced rail and ground movements.When railway vehicle speeds approach critical velocities in the track ground,the movements may lead to excessive rail deflections and associated noise and structural vibrations in houses in the vicinity.Three-dimensional(3D)models were developed with Multi-Body System(MBS)software as well as Finite Elements(FE)to study the dynamic response of the vehicle-track-embankment system for metre and standard gauges subjected to moving loads.Firstly,the railway vehicle was modelled in SIMPACK MBS Software to model the railway vehicle at different velocities.Due to wheel-rail interaction,the vertical wheel forces and derailment quotient were obtained.Secondly,the vertical wheel forces obtained from SIMPACK MBS were used in the Abaqus/CAE,the Finite Element Analysis(FEA)software to model the track.Therefore,the effects of railway vehicle speed on the two gauges were determined on the track components'dynamic responses:acceleration,displacement,stress,reaction forces,and wheel-rail contact forces.The dynamic analysis findings have indicated that the metre gauge experiences higher dynamic response compared to standard gauge.This can result in minimum speed,low axle load,and ride comfort to the passengers in order to keep the dynamic responses within the acceptable limits.This can result in poor performance as the capacity,speed,and comfort are the key factors and therefore,not able to compete with other modes of transport.This is the case in Tanzania,whereby,railway transport seemed to be abandoned and not reliable before the hopes went up again when the standard gauge construction started in 2017.A considerable investment on the Standard Gauge Railway particularly in Tanzania is of paramount importance.