The MacWall “Landmark” retaining walls have been installed at the Stockman’s Lane Junction of the Belfast Westlink, one of the City’s principal arterial roads handling over 65,000 vehicle movements per day and part of a £115m, M1 motorway improvement scheme being undertaken by Contractors HMC [Highway Management Construction] for the Northern Ireland Department for Regional Roads Services.

 

Sited within a heavily built up area of the city, HMC was faced with the problem of widening the road from 2 lane dual carriageway, to 3 lane plus hard shoulder, whilst maintaining the same overall highway footprint – no additional land take was possible. Two new bridges were required to span the Stockman’s Lane circulatory system beneath the motorway and slip roads had to remain in use throughout the work.

 

HMC’s solution was to install near vertical, masonry-faced reinforced earth retaining walls between the new carriageway and the slip roads. Four walls were constructed, each approximately 150m long and up to 4m high. 

 

Detailed design was undertaken by retaining structures specialists Maccaferri, who specified MacWall Landmark Segmental Retaining Wall solution, incorporating Enkagrid PRO polyester geogrids for reinforcing the structural backfill to the wall.

 

Explaining the choice of the MacWall Landmark System, David Crowther, Technical Manager for Maccaferri said; “MacWall Landmark is one of only a handful of retaining wall systems that carry British Board of Agrement [BBA], Roads and Bridges Accreditation. MacWall Landmark gave us the assurance of a proven system with a design life of 120 years. It is also approved by Northern Ireland’s Road Services for use in structures requiring TAS approval so we were confident of its performance.”

 

“MacWall Landmark met the objectives of the project by enabling the road to be widened within the existing highway footprint. Also, because it’s a dry-laid, mortar-less system, it was quick to install during the off-peak work periods” added Crowther.

 

The M1 Westlink project is the first major highway infrastructure use of the MacWall Landmark system in the UK and Ireland. 

 

The Westlink reconstruction is a DBFO package [Design Build Finance & Operate], and is also the first of its kind in Northern Ireland. Construction work began in early 2006 and will continue until early 2009.