ElevArch

Structural Designer

Freyssinet and BHA

Client Name

Network Rail | RSSB

Location

UK

PROJECT DESCRIPTION

It is estimated that 500 masonry arch bridges in the UK are too low for Network Rail’s electrification programme. A cost-effective solution is required to avoid the demolition of hundreds of overbridges. In 2014, Freyssinet took part in RSSB’s Avoidance of Bridge Reconstruction competition joining forces with masonry arch expert, Bill Harvey, to explore the feasibility of vertically jacking bridge arches. The resulting ElevArch® concept was selected as one of four to advance into phase two of the competition - the full-scale demonstrator. This cutting-edge technique and sustainable solution for jacking rail masonry arch structures avoids unnecessary demolition and reconstruction for electrification schemes throughout the UK.


 

Judge's comment:

The judges were impressed by the potential the ElevArch system has to solve significant logistical problems associated with increased height requirements on rail lines. The carefully developed system and sequencing provides continuous restraint and support the masonry arch through a series of jacks and vertical slip bearings inserted in key locations cored into the masonry bridge. The lifting operation was carried out after wire saw cutting the arch – with the 50-tonne capacity jacks computer controlled to an accuracy of 0.1mm to ensure a synchronous lift. Monitoring was carried out throughout the lift to verify the arch behaviour.

The final bridge position was 435mm higher than original – permitting limited reprofiling of the approach ramps and supports reinstated by flooding joints with concrete.

The judges recognised this inventive system could only be realised with the engineers’ deep knowledge of masonry behaviour and lifting processes. It has the potential to transform and retain many bridges to meet the challenges posed by rail modernisation, whilst dramatically reducing costs and disruption to rail services during electrification works.