Learning legacyLessons learned from the London 2012 Games construction project

Reducing hazards of installing gabion wallsGabion retaining walls have been used extensively across the Olympic Park on bridge abutments. During installation the thick galvanised wire forming the gabion baskets were cut to shape leaving exposed sharp ends of wires. These ends were temporarily capped with modified small diameter ductwork which reduced risk of injury and also improved installation efficiency for infilling.

Gabion walls A gabion wall is a retaining wall made of rectangular containers (baskets) fabricated of thick galvanised wire, which are filled with cleaned stone, crushed concrete or similar and stacked to the required height, usually in tiers that step back with the slope rather than vertically and tied together for stability. Gabions also have advantages over more rigid structures because they can conform to ground movement, dissipate energy from flowing water and drain freely.

Risks associated with installing gabion walls Gabion baskets were used as part of the design solution to enclose some permanent and temporary unfinished bridge structures. Due to the design of some bridge abutments it was not always possible to install accurately shaped prefabricated baskets which would slot together when on site. Altering the gabions was achieved by cutting the galvanised wire baskets at selected points to form the required shapes.

Gabian wall under construction – exposed wire ends capped with modified ductwork

This left exposed sharp ends of the wire, which if left unprotected represented a significant hazard and risk of injury to the installation team and others having access to the work area.

To remove this risk an end cover was required for the exposed cut wire ends. The use of plastic ‘mushroom caps’ was not an option as they were too large in diameter. A large number would have been required for each section if the right size could have been procured and would be time consuming to install and remove.

Solution developed to mitigate the hazard The solution was to utilise a section of small diameter ducting (excess to requirements elsewhere), cut along the length and placed on top of a section of the exposed wires. It was important to use ducting that was flexible and easy to cut safely. This provided good protection against any potential injury and was easy to manage, install and remove.

An added benefit of using the plastic protection is that it speeds up filling and results in less ‘spillage’ over the top of the basket.

Capping reduced the risk of injury and improved filling speeds with less spillage

Partially infilled gabion wall capped with modified ducting

ProjectStructure Bridges and Highways – LO3 Bridge

SupplierBalfour Beatty – Tier One Contractor

AuthorKevin Jewitt – Heath and Safety Assurance Manager

© 2011 Olympic Delivery Authority. The official Emblems of the London 2012 Games are © London Organising Committee of the Olympic Games and Paralympic Games Limited (LOCOG) 2007. All rights reserved.

The construction of the venues and infrastructure of the London 2012 Games is funded by the National Lottery through the Olympic Lottery Distributor, the Department for Culture, Media and Sport, the Mayor of London and the London Development Agency.

For more information visit: london2012.com/learninglegacy Published October 2011ODA 2010/374