Civil Engineering


M621 Parapet Renewal


AGC, the AmcoGiffen and Carnell partnership, have successfully delivered another parapet renewal for National Highways. The M621 Gildersome interchange parapet replacement scheme was completed in August 2023 through the Scheme Delivery Framework (SDF) contract, for which AGC are the Road Restraint Systems lot provider in the Yorkshire North East region. 

With the parapet having reached the end of its serviceable life, 240m of N2W1 vehicle parapet was removed and replaced, along with the associated transitions to the existing verge vehicle restraint system (VRS), in eight locations. 

As principal contractor, AGC delivered the scheme in collaboration with Jacobs (principal designer), and HW Martin (traffic management). The programme of works was carried out over four phases on both the clockwise and anti-clockwise carriageways of the M621. Working with sector scheme approved manufacturer Versco and National Highways’ safety and engineering standards division, the technical approval process for the temporary and permanent works approvals was navigated, to achieve the desired programme start and completion dates.

Overcoming Challenges

AGC’s experienced team provided engineering solutions to mitigate issues with underground services. 

Issues arose in the approach and departure areas of the verge on the north bridge (clockwise carriageway). In addition to the already congested location which contained ducted power and NRTS systems, several uncharted and directly buried cables were located during excavation. 

Following further excavation, and after exploring all options available, a foundation raft design was proposed by AGC to give maximum protection to the services once the transitions were completed and brought into service. This was agreed and formalised by Jacobs. The scheme phases were re-worked to minimise lost time for the delivery teams while the new designs were created.

The collaboration between all partners ensured that safety, customer and delivery benefits were created.


  • Supporting National Highways’ Home Safe & Well approach with zero lost-time incidents and zero AFR. 
  • Free from service strikes, despite the presence of uncharted cables and a high volume of lighting and communications cables.  
  • Improving the safety of future maintenance operations through split-ducting the direct-buried cables.
  • Minimising the impact on the road-user through using lane closures and varioguard instead of full closures for protection of the works. 
  • Re-phasing the scheme on encountering unforeseen circumstances to mitigate delays to completion. 
  • Improving road-user safety by renewing an asset at the end of its serviceable life. 
  • Creating efficiencies by providing engineering solutions that overcome challenges presented by uncharted cables.   
  • Responsive delivery through collaboration with the client, designer, and traffic management provider. 
  • Delivered on time and efficiently. 

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