The unique integrated road and rail delivery team provided a safe and successful solution for essential work to replace 240 metres of logistical and technically challenging bridge parapets on behalf of National Highways.
The scheme, located on the A180, a two-lane, dual carriageway near Ulceby, in Lincolnshire, crosses over two railway lines along a 200-metre stretch forming what is known as the ‘Railway Triangle’. The formation connects Immingham and Grimsby docks with the rest of the UK and is strategically important in maintaining the supply and transportation of key commodities.
A solution to replace the bridge parapets above these railway lines has long presented a challenge to National Highways, due to complex safety and regulatory standards required by Network Rail, the rail track asset owner, to undertake structural improvements over the railway lines.
Full Steam Ahead for AGC
The collective skillsets of AGC include AmcoGiffen with over 50 years working in rail, and Carnell with three decades of experience on the strategic road network, successfully overcoming the challenge created by the complex road-rail interface.
The scope of work included:
Installation of four high-containment parapets, each 2.2 metres high and approximately 60 metres long
Eight barrier transitions which close short gaps between two sections of different safety barriers
During the work, an additional 800 metres of the surrounding corrugated steel barrier was identified as requiring replacement, this was effectively absorbed into the programme resulting in almost 1,200 metres of vehicle restraint system (VRS) upgraded in total.
Developing the Optimum Solution
AGC worked with supply partner Versco, a local small-medium enterprise to develop the most appropriate solution. Their VC+EB-L2 parapet system includes an integral solid panel screening at the rear to N2 and H2 containment classes.
The benefits of this system are:
1. Effective and efficient delivery | To avoid unnecessary risk to the structure whilst drilling, the new parapet post baseplate and anchorage arrangement were developed to position over the existing anchorage cluster, and the post distribution layout was altered such that the post centres of the new system matched existing over two-thirds of the renewal scheme. Additional flexibility for anchorage positioning was also introduced via longitudinal slotting in the baseplate.
2. Less disruption for road and rail users | The solid face cladding panels at the front of the system are affixed to the strike-rails by blind rivets which is a time-consuming installation, but once installed, the integral solid panel screening at the rear of the parapet system meant solid face cladding panels could be fitted from the highway face without the need for additional track possessions this reduced the length of time required for track possessions.
3. Safety | The construction of the solid panel screening to the rear of the posts is affixed through bolts, which limits the number of operational personnel and time on site. Lightweight sectional installation of panels allowed for safer and easier manual handling
The solid cladding and steeple coping were added following the requirements of CD377 and BS6779-1:1998 and Network Rail conditions.
Versco also developed the temporary works specifically to suit Network Rail requirements. The 1.8 metre-high solid-clad edge protection system provided a temporary situation aligned with the permanent parapet solution, ensuring no objects could fall onto the rail track. This required several detailed desktop exercises following initial early contractor involvement including surveys of the existing parapet, stringcourse arrangement and ferro-scanning activities.
Overcoming Barriers Collaboratively
The A180 Railway Triangle scheme is part of National Highways' vehicle restraint system contract on its Scheme Delivery Framework (SDF). AGC worked closely with the National Highways, Jacobs as principal designer and HW Martin Traffic Management.
As the principal contractor, AGC managed the programme during construction self-delivering the bulk of the VRS activities with additional support from trusted supply partner Versco.
Behind the scenes, the unified AGC team successfully negotiated several challenges.
Stakeholder Collaboration - construction work over, under or adjacent to operating rail tracks requires possession arrangements to be granted by Network Rail before work is permitted. Each possession takes 16 weeks to process and requires thorough justification, to limit the disruption to passengers and freight and because once confirmed it cannot be changed. The project team built and sustained excellent relationships with Network Rail to ensure this lengthy procedure went smoothly.
Programme Optimisation - The lead time and rigidity of rail possession meant the programme had to be accurate and optimised. The schedule of work between possessions was demanding but also acted as hold-points; safety, customer impact and efficiency had to be carefully balanced to give certainty of delivery without being over cautious.
Buildability – There are statutory restrictions around mechanical lifting close to rail lines. To work around these, key components of the heavy-duty, high-containment parapets were designed to allow manual handling during installation.
Key Roles – Another condition for construction around the operational railway is that specified key roles must be approved by Network Rail who operate the network licence. AGCs team includes rail-competent colleagues, equipped with the necessary skills, experience and qualifications to oversee the site works and manage the nine rail possessions safely and efficiently.
Added Value – During construction, AGC engineers identified another 800 metres of the surrounding VRS beyond serviceable repair. The team’s skilled project manager has a background in highways and was able to support the design and approvals required to replace the additional barrier section. This direct resource and experience ensured the design was turned around within a shorter timescale than if managed externally.
Temporary Works - Significant temporary works were coordinated by the specialist delivery team, including edge protection being installed over the tracks to meet the many regulations and standards for working at height. This ensured safe working conditions and eliminated the risk of falling debris during the dismantling of the redundant system and installation of the new solution.
Engineering Solutions – By design, two-thirds of the original bridge parapet post and anchorage positions were reused, however, the remainder of the anchorages were to be sited at new locations. Steel reinforcement within the string course of the plinth restricted anchor positioning at new locations, so a series of engineered treatments were developed and agreed upon with the principal designer to overcome this issue.
Building a Track Record of Successful Delivery
AGC safely and successfully replaced four high-containment parapets that were beyond serviceable repair, overcoming numerous challenging factors. The combined expertise of the partnership successfully delivered a scheme historically seen as ‘too difficult to do’ due to the complex road-rail interface. Working collaboratively with the National Highways and Network Rail, the project was safely completed with minimal impact on customers and stakeholders, incorporating additional activities, and under budget.
John Stebbing, Project Manager for National Highways, said: “I have nothing but appreciation and commendation for the work that AGC completed on this particular scheme. A huge amount of planning in advance of the site work in conjunction with Network Rail and the appointed Principal Designer was led by AGC to ensure a seamless and reduced risk of delivery.
“This level of organisation and commitment was echoed throughout the project lifecycle and resulted in an incident-free and professional conclusion to the works and handover of all relevant close-out information in a timely duration. A very successful and well-received project all round.”
Bryan Kennedy, Operations Director, AGC, said: “Through the combined expertise of our highways and rail colleagues, and in collaboration with our specialist supplier, Versco, we successfully delivered the highway barrier replacement scheme at this complex road-rail interface.
“The design, meticulous planning, and installation of the barrier in this unique and economically critical location were achieved through seamless teamwork, ensuring a safe, efficient and effective delivery with minimal disruption to rail and road users."
Scheme Benefits
Safety
- 0.0 AFR for both National Highways and supply chain staff
- Zero RIDDOR or Lost Time Incidents
- Treatment and removal of hemlock from the verge (a poisonous invasive plant species)
- 25 positive interventions recorded to improve site safety
Customer
- Full closures carried out overnight at weekends limiting disruption to road users, passengers and freight
- Close liaison with stakeholders including Network Rail
- Nine rail possessions fully utilised
Delivery
- Additional barrier works absorbed into the programme
- Specified works delivered under budget
- Delivered an additional £200k of barrier works at National Highways’ request.
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