Case Study—Railway Embankment Widening for CN Rail and GO Transit

GO Transit, The Greater Toronto Area's commuter rail/bus system is currently undergoing an expansion in service. Part of this expansion is an improvement in the limited rail service between Toronto and Hamilton Ontario. In some cases, in order to meet the increased commuter volume, it is necessary to add additional tracks to accommodate the existing and future rail traffic. This is the case on the Lakeshore West Line where a third track was only the way to meet demand. In the Lorne Park area of Mississauga, existing conditions did not provide sufficient room for a number of rail embankments to be widened without the use of an earth retention system. Numerous retaining wall and over-steepened slope options were considered for seven distinct locations. The ultimate solution was a prototype Mechanically Stabilized Earth (MSE) retaining wall that combined a steel fascia with geosynthetic reinforcement. This case study will examine the various aspects of this project from the initial stages of design, through the various solution options, to the development of the final solution. With a restricted time schedule and construction constraints, the paper will also detail how those major obstacles were successfully overcome in the completion of this project.