New geophysical and geotechnical approaches to characterise under utilised earthworks

Transferring the freight burden from road to railwould bring about many environmental benefits. The Rail Contribution to the Energy Review (Dept. for Transport 2006) indicated that rail freight produces eight times less CO2 per tonne.km than road freight. Implementing this strategy successfully will require further development of rail infrastructure to cope with additional capacity. Many new proposals, such as the EuroRail Freight Route, would utilise redundant and under-used infrastructure, much of which was constructed during the latter part of the nineteenth century. Earthworks of this age should be regarded as unique if they are to be improved or upgraded. Such upgrades would require investigations into the condition of the existing earthworks to assess the materials, variability in the geotechnical properties and engineering performance along the proposed route. This paper presents a section of embankment from the Great Central Railway as a case history that demonstrates the integration of a number of geophysical and geotechnical data to assess the condition of an embankment in relation to fill materials and track geometry. It emerged that embankment structure and strength information can be provided via combined use of non-intrusive mechanical and electrical techniques such as continuous surface wave profiling and resistivity surveying. It is envisaged that this information can be used to strategically plan intrusive investigations and works to improve the infrastructure.