In order to provide a reliable support to ballasted track for high speed railway lines under the onerous geometrical constraints and soft ground conditions covering 7km of CTRL crossing the North Thames marshes, careful analysis of pile loads and associated cumulative settlements was necessary. A design methodology involving full scale, cyclic pile load test results coupled with full 3D dynamic finite element analyses has enabled a structurally efficient and cost effective foundation solution to be found and implemented on site. It is recommended that, for high speed lines which cross such soft ground conditions, special methods of analysis and design following those presented herein are required where the ratio of live (train) loading to dead (static) load on the support system exceeds 0.5.
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