Major part of the investment in UK rail infrastructure has been spent on electrification of the existing network with Overhead Line Electrification (OLE) requiring significant investment to provide the long term benefits. The pressure reduce the cost of electrification works has brought cuts in the ground investigation budgets resulting in a significant drop to one borehole investigation for every 500 m length of rail track and general lack of ground information available for most of the proposed overhead line mast foundations for OLE projects. The current piled foundation design in the UK railway industry is based on experiment and research-developed system (Overhead Line Equipment Master Index - OLEMI), whereby the foundation length is derived for worst-case ground conditions leading to overdesign of foundation size for safety and stability. Ground investigations are only carried out when the ground is very poor or when the foundation designed to the method known as fails. The research method for this paper is based on gathering historical geological data from the British Geological Society, designing pile foundation using conventional design codes and comparing the foundation depth against OLEMI-designed foundations for a case study from the Scottish Central Belt. The results showed that conventional foundation design can provide about 50% savings on overall foundations depth. Detailed analysis showed that some OLEMI-designed foundations did not have enough lateral resistance and anchors had to be added. Moreover, about 99.5% of the OLE foundations were shown to be overdesigned due to the fact that they were installed on firmer soil conditions and shorter foundation would have been sufficient to act against the disturbing acting moment. Therefore, a balanced approach of using geological information from historical sources and allocating additional intrusive and non-intrusive ground investigation was shown to be beneficial for reducing construction costs on overhead line projects.

OLEMI, ground investigations, pile foundations, bearing capacity