MAY GURNEY Structures Partnership has installed inclinometers and piezometers to monitor a railway embankment in Ilkley, Yorkshire for network operator Railtrack.
One set of instruments will detect movement at track level and the other will monitor movements and groundwater pressures in the underlying ground.
The embankment has been a problem for more than 50 years and several site investigations have been undertaken since 1962.These have shown the underlying geology to be mudstone from the Millstone Grit Group, overlain by boulder clay.
Historic primary slips pass through the underlying mudstone strata and are thought to date back to the last Ice Age. Secondary slips, debris and earth flows have since occurred and periods of bad weather are threatening to reactivate such slips.
May Gurney's Hutte mini piling rig was used to install four trackside inclinometers to depths of 9m within two six-hour 'green zone' possessions. Steel drive-in piezometers were then installed using the firm's Geotool dynamic probe rigs.
Specialist rope access contractor CAN used its specialist drilling rig to install inclinometers on the embankment slopes.The instruments are solar powered and provide 24hour monitoring of groundwater levels and track movements.
In the event of an emergency, telemetry links send alarm messages to the local signal box and to the Railtrack control centre in York so that appropriate action can be taken.
The links are also used to download data directly to May Gurney's Trowse office for evaluation, to aid the design of remedial measures. This keeps speed restrictions to a minimum and the line open for rail users.