Repairs to electro-slag weld defects on M4 Boston Manor viaduct

Abstract

Opened in 1965, the 1 km long Boston Manor viaduct carries the M4 motorway into London, UK, and formed part of the London 2012 Olympic route network. A 7·5 t weight restriction was introduced following the discovery of cracks to electro-slag welds in early 2012, after which an emergency solution was needed to remove the restriction in time for the Olympic Games. The extent of the cracks had to be quantified before repairs could begin. With the exception of closing the structure for 6 d to repair a live crack, the solution was implemented with minimal disruption to traffic in just 3 months. This paper describes how the solution was implemented to remove the restriction, enabling the viaduct to remain open for the Games and beyond.