Amiblu – Case Study

Flood risk management in the UK relies in part on the use of culverts to allow the rise and fall of flowing or flood waters to run through a structure or obstruction into an existing water course.  Often, culverts are bridge like structures creating pedestrian or vehicular traffic to cross the water course and are constructed in a variety of shapes and from a variety of materials, depending on the performance criteria set out at the time of construction.

There are thousands of culverts across the UK that are now in need of repair or rehabilitation and in a lot of cases the performance requirements have also changed, they may require strengthening for increased traffic loads; they may require reshaping to accommodate ground movement or the hydraulic performance may be hampered by corrosion or build up of silt and vegetation, or they are just coming to or passed the end of their expected lifetime.

Fig 1: Courtesy of V & B Paving
Twyford Land Arches West is a single span brickwork culvert. The bridge is located between the districts of Charvil and Twyford, Berkshire and carries the two-lane carriageway of Old Bath Road (A3032) over an un-named flood relief drainage ditch. The deck of the culvert is a 3 ring segmental profile brick arch with a clear square span of approx. 3.05m and an overall width of approx. 10.21m.

An assessment was undertaken by WSP in 2012 which indicated that the structure passes 12.5T & Group 2 Fire Engine (G2FE) Assessment Live Loading (ALL).  An options study was undertaken to strengthen the structure to full 40T capacity.


Fig 2:  Courtesy of V & B Paving
Amiblu’s circular relining pipe was chosen due to its low initial costs, low whole life cost due to the long design life of the GRP pipes. There are clear benefits of using the GRP pipes which are installed into the culvert and the anulus grouted up, such as: being able to keep the road open to vehicles and pedestrians, having a reduced construction programme, not having to dispose of the existing structure, not having to disrupt any of the services.

Amiblu’s Hobas centrifugal cast pipes  provide capacity to withstand high traffic loadings and maintain excellent long-term stiffness, corrosion and abrasion resistance and are engineered for 150 years‘ service life.


Client:                                     Wokingham Highways Alliance

Consulting Engineer:              WSP Basingstoke

Contractor:                             V & B Paving Ltd.

Project Date:                          Summer 2020


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