North Beck Bridge, Northallerton

The new 900m long link road and 150m span weathering steel bridge connects two housing developments in Northallerton, North Yorkshire, forming a bypass taking traffic from the centre of Northallerton.

The project involved forming new highway approach embankments up to 15m in height, with new RC bridge abutments and twin piers founded on 20m long 900mm diameter CFA piles which, in turn, supported the four weathering steel beams and cast in-situ reinforced concrete deck.

The bridge spans the railway line between Northallerton and Teesside, therefore all works associated with the bridge required approvals from Network Rail.

The project was secured through an open tender heavily weighted towards quality with tenderers having to demonstrate their experience of working with Network Rail and bridge construction work. EWCE has held a Principal Contractors Licence with Network Rail since 2012. All temporary works for the piling and crane platforms had to undergo Network Rail’s stringent review and approvals process. We undertook CAT 3 temporary works designs and checks to facilitate these approvals. This included lifting close to and over Network Rail property with cranes up to 1000T in size and booking of possessions for works directly over the line.

The project involved extensive earthworks to form the new approach embankments by importing over 100,000m³ of granular material 15m in height, with band drains under the footprint, geotextile basal reinforcement, a drainage layer and extensive geotechnical monitoring during construction on the soft alluvium.

The works required strict controls and checks to ensure they had been constructed in accordance with the specification. The monitoring was installed to ensure we did not over-stress the underlying soft ground. We monitored the works on an ongoing basis and reported back to the client and their designer, AECOM to verify stability of the ground before progressing with subsequent earthworks phases.

The works also included the diversion of the North Beck (an EA Main River) and extensive flood alleviation works, attenuation ponds and landscaping.

The new weathering steel beams were supplied by Cleveland Bridge, who we appointed in Spring 2020 during the height of the pandemic. We met with numerous suppliers and eventually settled on Cleveland with their extensive experience of similar large scale structures and long established history in the region.

Design and detailing queries were all resolved in good time working with ourselves, Cleveland, AECOM (Client’s designer) and North Yorkshire County Council (adopting authority). Procurement of main beam materials progressed according to the programme we had agreed with Cleveland which allowed ordering of materials prior to any price increases.

We secured all other materials required to construct the bridge, aware that transportation was taking longer to arrange, and lead-in times for all materials were typically increasing across the industry.

Fabrication progressed whilst we were constructing the embankments and RC structures on site ready to accept them.

During this period, we developed and finalised our temporary works for the crane platforms, temporary trestles and temporary restraints for the structure. These were all submitted to, and approved by, Network Rail.

We worked with AECOM to allow the stringcourse falsework to be pre-erected on the beams, even though this was not allowed at tender stage. We verified the temporary stability of the beams and determined the amount of falsework that could be pre-erected. We modified the specified erection sequence to assist and de-risk site installation. Again, this was approved by AECOM and Network Rail.

Approximately 4 weeks before the main bridge lifts were due to take place, Cleveland Bridge went into administration. This had the potential to affect the programme and jeopardise the safe supply of the steel that we were already contracted with them to provide.

As part of our sub-contract and the main contract with the Client, we had already entered into an appropriate vesting agreement, thereby safeguarding the supply of the steel in such instances. Our site and commercial teams immediately ensured our steel was safeguarded. We visited Cleveland to verify the current stage of fabrication and identify what missing elements still needed to be provided. We engaged closely with Cleveland’s commercial representatives and the appointed administrators to ensure we safeguarded the supply and outlined our legal title to all materials.

We immediately contacted Cleveland’s supply chain and set up our own orders with their key suppliers, including;

• Collets (transportation)
• MJ Hughes (site erection, crane lift and temporary works)

We took on board the role of Cleveland to manage the remainder of the fabrication, temporary works and site installation. After our quick and decisive action the main bridge beam installations over the rail went ahead as planned albeit one week behind schedule on the weekend of Saturday, 18th September with no issues. Both sets of braced pairs were erected during the limited rail possession from 10.00pm Saturday to 8.00am Sunday. Subsequently, we installed the remaining steel thereby allowing the RC deck works to progress unhindered.

The site was registered with Considerate Constructors and achieved a Certificate of Excellence.