Benefits to Client
Rapid response to carry out emergency works after a disastrous flood event.
The Problem
In November 2009, the north west of England experienced widespread flooding. In the town of Workington, one road bridge collapsed and the other was deemed unsafe. The town was divided in two. The Royal Engineers were commissioned to build a temporary footbridge over the River Derwent. The Engineers required immediate design guidance on stabilisation and delivery of geogrids within 24 hours.
The Solution
The use of multiple layers of Tensar TriAxTM geogrid combined with locally sourced stone enabled Army Royal Engineers to begin construction of the bridge assembly, the launch platform and the bridge abutments less than 24 hours after the initial call for assistance from the local authorities.
Product Description
In November 2009 the town of Workington in Cumbria experienced severe flooding. One bridge in the town collapsed and the other was deemed unsafe. This left locals with an 18km round trip to travel from the north to the south of the town. Army Royal Engineers were commissioned to build a temporary footbridge to connect the two sides of the town. The selection of the site and the soil testing were carried out immediately. Tensar International was given a brief to return design advice and to organise an express delivery of Tensar TriAx geogrid. An Application Suggestion was produced the same day, to illustrate the appropriate use of geogrids, and material was delivered the following morning.
The banks of the River Derwent consist of sandy clay soil with poor load bearing properties. By constructing the abutment bank seat supports, as well as the bridge assembly platform, using Tensar TriAx geogrid and locally sourced stone, the time and cost involved in any other stabilisation methods and support services were avoided.
Referring to the bridge abutments, Captain Caroline Graham-Brown of the Royal Engineers commented “Normally the bridge would be built on existing abutments or temporary abutments on a river bank. In this case the saturated topsoil was stripped down to the sandy clay below and the platform was built up using the TriAx geogrid. A platform was built with multiple layers of TriAx geogrid and a minimum of 400mm of DOT Type 1 sub-base aggregate”.
Captain Graham-Brown went on to say that “the MOD has used Tensar geogrid solutions in the past for infrastructure projects with excellent results”. Major Phillip Curtis confirmed that “Tensar responded magnificently to our requirements, both in contributing to the design(1) and specification and getting the geogrid to us within a day of our call”.
In recognition of the delivering of the solution, British Construction Industry awarded the project the ‘Thomas Telford Civil Engineering Award’. The judge’s comments read “What makes this project special is the extraordinary speed with which the solution was envisaged, the design developed, land acquired and project delivered”.
