CONSULTANT DONALDSON Associates is designing remedial works for dozens of railway embankments and cuttings in Scotland.
Railtrack has scheduled 36 sites in the second year of a project to target high-risk slopes for remedial works. John Mowlem, Edmund Nuttall's geotechnical subsidiary Ritchies and Carillion are carrying out construction.
Ritchies has started construction on 10 cuttings on the Kyle line in the west Highlands. The Glasgow-based contractor is stabilising a series of long and deep rock cuttings by a combination of rock bolting, anchoring and shotcreting, together with the use of rock fall entrainment and high tensile strength tensioned containment netting.
In an area with a high slope above the boundary fence, a high strength flexible debris slide fence has been designed. Donaldson is designing solutions to similar problems associated with rock cuttings for sites near Mallaig, between Edinburgh and Glasgow, in Paisley and Gourock.
In another contract, Mowlem has completed a £1.3M project to stabilise a 500m long, 20m high cutting in glacial deposits. Work required reprofiling the slope, which comprises fine silty sand overlying stiff clay.
The change in geology on the slope is marked by a spring line causing sand to be washed out, over-steepening the slope. The slope failed earlier this year while Donaldson was carrying out design.
Carillon has begun remedial works to buttress and strengthen an 800m long, 20m high embankment founded on soft alluvial silts and clays.
Donaldson director Andy Sloan said works have been designed using a careful selection of engineering materials while minimising import requirements.
'The work presents a large, interesting and challenging package of slope design, ' he said.'The emphasis is on innovation and buildability to optimise benefits to Railtrack. Close liaison between contractors, designer and client in the design stages is allowing the rapid start of construction.'