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Infrastructure - Innovation in Action at Infrastructure project M25 Junction 20 closure lifts - HS2 Denham Site Compound - Osbourne

Gade Valley Viaduct is a multi-span composite viaduct carrying the M25 between Junctions 20 and 21 at King’s Langley. The 450m long viaduct is composed of twin decks, each formed from four open topped steel box girders with an in- situ cast concrete slab.
Infrastructure - Innovation in Action at Infrastructure project M25 Junction 20 closure lifts - HS2 Denham Site Compound - Osbourne

Project Overview

The complex refurbishment scheme of repairs, coatings and a new deck to Bridge 6 began in summer 2018. Due to a lack of fatigue strength in the bottom flange over 50,000 strengthening components are required, each with their individual quality record. This includes: 750 weld dressings, 2500 strengthening plates, 48000 bolts and 1000 paint sections.

Large motorway bridges expand and contract with changes in temperature. Movement joints allow this to happen but at Gade Valley Viaduct
on the M25 the joints were worn and needed replacing before they came to the end of their serviceable life.

Closing the motorway during the daytime is hugely disruptive so the team used an innovative method, developed on the M25 QE2 Bridge, which enabled the work to be undertaken with just night-time lane closures.

A heavy temporary cover plate and ramp system is installed over the existing joints. Over ten consecutive nights the ramps are lifted out to allow the joint to be cut out using hydro-demolition. Every morning the ramps are replaced and normal 70mph traffic can return to running. Highly efficient logistical solutions have accelerated operations while eliminating any risk of damaging services or hidden structural elements. As part of the contract several lifts took place to unload the transport & place the expansion joints into storage on the ground and to perform a test/trial lift at the HS2 Denham Site Compound. Ainscough reported to Denham Compound to load the joints onto transport, then followed onto Gade Valley Compound J20 M25 to offload & place as required onto the road surface. The works took place at night during a full Carriageway closure of the M25 around J20 Hertfordshire.

What were the benefits?

Infrastructure projects are amongst the most complex and time critical in construction We are a leading supplier of design solutions and cranes in infrastructure for governments and private-sector clients.

Our learning culture and engagement is all about sharing the experiences and benefits of innovation with our partners. Working on full contract lift with 55 tonne Liebherr, Hiab transport and heavy haulage transport solutions. These examples serve to show how we always aim to apply innovative transport solutions and methods to deliver greater value and improve the experience, both for our customers and asset users.
Clients need to know they are working with a partner who will protect their reputation through flawless delivery to often-immovable deadlines. We understand the multiple functions these facilities have to serve and we apply our in-depth knowledge of complex infrastructure projects to maximise return on the clients’ investments.

From the early stages of the project, Ainscough Crane Hire was on-site to help with the logistical and transport aspects of manoeuvring materials and equipment at the site. Through sharing the Ainscough innovative and learning culture, our customer also gained a greater appreciation of the strength and capability of the Ainscough team.

Further Details

Work started on site the complete project will be completed Summer 2018 as part of HS2 works.

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