Following the successful opening of four miles of new lanes on the A1 Birtley to Coal House scheme, Costain managed the complex demolition of the old Allerdene Bridge, spanning the East Coast Main Line, one of the busiest railway routes in the UK.
Enabling works began in 2022 and the demolition itself was completed over seven possessions, running from Christmas Eve 2024 until March 2025. The works were completed to schedule with no operational delays to the railway line, despite being confronted with a number of unique logistical and engineering challenges.
Read on and watch the video below to see how the demolition was managed.
About the A1 Birtley to Coal House upgrade
The four mile stretch of the A1 between junctions 65 and 67 at Birtley and Coal House runs past the iconic Angel of the North. The existing road, previously prone to congestion, has been widened to help manage traffic joining and leaving the dual carriageway, improving journey times, safety and mobility in and around Newcastle and the Tyneside area.
Costain has managed the scheme and served as the on-site partner for National Highways.
The scheme has provided a lasting social impact for local communities. Costain has provided construction training and qualifications to more than 100 former service leavers and veterans via a partnership with the charity Building Heroes.
About the works
The proximity of the Allerdene Bridge to the East Coast Main Line brought unique challenges and required careful contingency planning with Network Rail. The bridge was also only 500m away from Tyne Yard, Network Rail’s main depot for rail maintenance teams, creating additional considerations when scheduling the works.
As a result, the seven possessions required to demolish the structure were scheduled almost a year in advance, with the team also confronted with beginning the works over the festive period whilst causing minimal disruption during a busy travel time.
Other challenges related to the bridge structure, which had fallen into a very poor state. This meant that soffit repairs had to be carried out on the structure just six weeks before it was demolished to ensure risk was appropriately managed.
The numbers
Zero
Minutes of operational delays to the railway
33,800
Working hours completed across the seven possessions
>100
Ex-service leavers provided with skills in construction
Our approach
Costain applied its best-in-class expertise to the complex project, taking the following steps:
Managing relationships with our client and key stakeholders
Developing a strong working relationship with Network Rail – as well as our client National Highways, was an immediate priority. This helped to mitigate delays to the works, including swiftly working on a contingency plan to prevent the cancellation of a possession due to a major football match involving Newcastle United and the resultant pressure on the railway network.
A safety-first approach
The proximity of the bridge to the railway heightened the importance of safety and risk management throughout the works. This mindset drove the decision to break out a maximum of 50% of the bridge deck over a single weekend to ensure that the railway could open as planned on Monday morning.
Costain also implemented a strong reporting culture, with hour-by-hour trackers in place to monitor delivery, helping to swiftly flag any issues and mitigate delays.
A multi-disciplined, in-house engineering team
To ensure best-in-class delivery of the works, Costain utilised its in-house engineering team and experience from multiple sectors, with lifting specialists, risk operators and quality managers assisting the project team.
The demolition works
The first of the seven possessions began on Christmas Eve, with the final possession taking place in March 2025.
Track protection had to be routinely installed on the railways adjacent to the bridge, with a track protection trial taking place over the festive period. This meant installing 455 white polystyrene blocks, 90 of which were bespoke due to the unique alignment of the railway. The successful trial provided important learnings for the following six possessions and the demolition of the bridge itself.
The remaining possessions were focused on the removal of the bridge deck and beams from the structure, followed by the back span section, and finally, the bridge piers and abutments.
The most significant possession was the removal of 12 bridge beams from the structure, a carefully managed operation which necessitated three and a half years of planning. This was in part due to the required lowering and reinstating of overhead line equipment, and rigging and de-rigging 450 tonne cranes.
The team developed a methodology and lift plan designed to prevent any disruption to the railway. This included identifying a method for the beam removal that meant track protection was not required for this possession. As a result, all beams were removed in one single blockade.
Delivering a best-in-class solution
Despite these myriad challenges, the demolition was completed on time and to the required quality and safety standards, with no delays caused to operations on the adjacent railway.
The completion of the works is another significant milestone on the scheme following the opening of the road lanes. Minor ancillary works are taking place before a smooth handover of the lanes to National Highways.
“This has been a complex project from the outset and we’ve worked closely with National Highways and Network Rail throughout. Together we have developed innovative solutions to unique challenges, ensuring the works were completed within the strict timeframes.
Josh Smith Construction manager on the A1 Birtley to Coal House project
“The scheme is improving the lives of those in the region by reducing travel congestion and helping to create a more resilient road network.”
Images taken before and after the demolition of the old Allerdene bridge. Credit - Costain
Contact
Ann-Marie Morrison
Sector director
[email protected]