Geotechnical
Banking on concrete blocks
Owen Batham describes how a form of ‘grown up Lego blocks’ proving to be highly successful in stabilising embankments in the road transport industry, could have a similar impact on the railways
T
he past few months have seen a series of high-profile cases where landslides, mudslides and collapsed embankments have
caused chaos on the rail network. The recent landslide at Hatfield and extensive damage to the track at Stainforth is currently causing huge disruption and late last year landslides resulted in major disruptions to lines at Westerleigh near Bristol and in Leicestershire – the latter incident leading to the derailment of a freight train and a closure of the line for 10 days. Luckily enough, such unpleasant episodes haven’t led to any deaths or serious injuries, but the disruption and delay to service, along with the requirement to carry out the necessary emergency repairs, are headaches that the industry could well do without. It also raises questions regarding the effectiveness of current embankment retention techniques.
Concrete blocks prevent subsidence The road industry has faced similar challenges relating to stabilising embankments over the years, and the solution it often turns to – using robust interlocking precast concrete blocks – could provide a more effective, not to mention quicker and less labour-intensive answer for the rail sector too. Commonly on railways, stabilising
embankments requires a team of contractors carrying out extensive civil engineering at locations which are often remote and/or difficult to access. These are time consuming and costly projects. By comparison, using interlocking precast concrete blocks is extremely quick, with 100m2
of embankment retention easily
achieved by relatively few operatives and limited equipment – the blocks can even be installed direct from the back of a freight train carriage using a crane. One of the key benefits that using
precast concrete blocks for embankment retention provides is the ability to prevent banks both above and below the railway line from subsiding. In Canada for example, interlocking blocks are also used extensively to retain rail ballast and prevent the lines being damaged by any nearby landslides. The blocks are also perfect for constructing ‘refuges’ quickly
and easily, again without the need for expensive and time consuming civils.
An additional safety benefit In our ongoing discussions with Network Rail and other industry insiders, a number of other areas have been identified where using precast concrete blocks could also have a hugely positive impact. Maintaining the nation’s railway network can be a particularly dangerous task, with Department for Transport statistics over the past decade consistently recording a handful of deaths, anything from 150 to 200 serious injuries, plus between 6,000 and 8,000 minor injuries each and every year. Official figures also show as many as 300 accidents a year are caused by passenger and freight trains colliding with objects on the track. At the moment on most track
maintenance jobs, it is commonplace for a simple line of tape held up between two posts to be put in place to differentiate which side of the line is being worked on. In theory, this tape is meant to prevent workers from walking out onto the ‘live’ track, while it’s also intended to stop
April 2013 Page 93
any machinery such as excavators from accidentally hitting oncoming trains. In reality, this hasn’t always proved to be the case, with some catastrophic (and life-shattering) consequences.
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