The HS2 southern approach from Northolt into London Euston shall be constructed as tunnels over 95% of the route. The tunnels shall follow the alignment of the existing Network Rail tracks and London Underground Central Line tracks between West Ruislip Station and Old Oak Common Station.
S2 and their design partners previously completed initial Ground Movement Assessments (GMAs) to assess all bridges and structures potentially impacted by the tunnels, creating a ‘short list’ of assets which could require mitigation in advance of the tunnelling.
RBG were tasked by main contractor for the S1/S2 section of HS2 Skanska Costain Strabag (SCS) to further refine bridge and structures assets from this earlier sifting exercise.
Key technical challenges
RBG undertook a detailed level of assessment for a number of bridges and structures in order to either conclude that no mitigation measures were required or recommend appropriate proactive or reactive measures. Where mitigation works were identified as required, RBG went on to design these.
Structures assessed included historic masonry arch bridges, composite highways bridges, steel and wrought iron rail bridges of various scales and forms, concrete subways, prestressed concrete beam bridges, steel footbridges, cast iron beam and stone slab bridges, and staircase structures.
Challenges included tight programmes to complete a large volume of work and deliverables to unmovable deadlines, extensive coordination with stakeholders and bespoke deliverables and assurance processes for a variety of asset owners.
RBG also undertook a large number of Category 3 checks for similar work of other design consultants
Added Value
RBG used both our detailed analytical and technical expertise and more focussed engineering thinking to successfully save our client from needing to carry out mitigation works to most of the structures we assessed.
Where works were required, we guided and advised our client in the various assurance processes required of the range of asset owners, due to our prior experience of work for these Technical Approval Authorities.
In our Cat 3 checks, we identified instances of where works had been recommended by another consultant after their detailed review stage, but we found alternative approaches and ways to remove this. This saved both financial impact, savings of material and impact to the environment, and exposure of workers to health and safety risks.
Sustainable Methodologies and Outcomes
RBG used both our detailed analytical and technical expertise and more focussed engineering thinking to successfully save our client from needing to carry out mitigation works to most of the structures we assessed.
Where works were required, we guided and advised our client in the various assurance processes required of the range of asset owners, due to our prior experience of work for these Technical Approval Authorities.
In our Cat 3 checks, we identified instances of where works had been recommended by another consultant after their detailed review stage, but we found alternative approaches and ways to remove this. This saved both financial impact, savings of material and impact to the environment, and exposure of workers to health and safety risks.
Project Metrics
Client:
HS2
Contractor:
SCS JV (Skanska, Costain & Strabag)
RBG Role:
Design
Construction Value:
GBP
Completion:
2024
Sector:
Rail, Roads & Highways
RBG Service:
Structural , Geotechnical