Business profile
Feel the strength of Cintec Rail’s support
Cintec Rail, part of the Cintec International Group, has developed a proven method of assessment, repair and strengthening for masonry arch bridges.
T
here are around one million masonry arch bridges in use throughout the world today, principally carrying road and rail. European railways alone account for 200,000.
These bridges are a vital asset and their replacement cost is almost incalculable. Despite their ancient form, masonry arches are notoriously difficult to accurately assess - their overall behaviour
masonry arch viaducts on the Glasgow and South Western (GSW) rail route at Crawick and Enterkin. This route is the main alternative to the West Coast Main Line connecting Glasgow to the South and carries a high percentage of freight and local passenger traffic.
Both structures suffered from similar defects – namely longitudinal cracks at the arch barrels behind the spandrel walls. However, in addition, Enterkin suffered
start developing the design for Enterkin followed later that year.
Real-time monitoring at Crawick revealed the cracks were widening so the programme was brought forward. The implementation of ties was started in January 2010 and completed within four months, with the installation of the Enterkin ties starting shortly afterwards. It was important to quickly establish what was underlying the ballast and confirm that the void filling had taken place, so a number of site investigation techniques were used including:
• Coring work • Excavation of ballast in confined location
• Laser scan of the Enterkin parapets • Radar scan at Enterkin • Panda probe testing
The Permanent Way team established from trial pitting that there was an excess of ballast on the structures. Over the years this had increased the loading and partly caused the current problems. A case was made to Network Rail for lowering the track, and it was subsequently lowered by 300mm at Crawick and around 250mm on the up line at Enterkin.
is complex, deriving from the interaction of individual parts, blocks, bricks, mortar and fill.
Cintec International has supplied anchors and reinforcement for the past 22 years, to Network Rail and previously British Rail, as well as county councils and local authorities, either directly or via its approved contractor network. Cintec and its partner companies are able to offer a complete diagnostic service on all masonry and stone bridges and structures, from initial assessment, and a finite element design process through to anchor installation and completion. Recent work took place at three locations in Scotland: Crawick and Enterkin viaducts and Keith Haughs bridge.
In 2009 Network Rail’s Framework team instructed Carillion to carry out site investigations and develop designs on two
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from deformation of the parapet wall. The design was for a fully developed reinforced U deck with through ties to stabilise the viaducts and extend their service life.
Historic documents and drawings provided enough detail on the make-up of the structures. Internal spandrel walls backing on to the arch barrels support stone slabs for the deck.
The original structural voids had been filled with concrete and all arches on the structures have longitudinal cracks behind spandrel walls. The cracks went from springer to springer on the outside of the bend on the line carrying most freight.
Design development work began on the Crawick structure in 2009, and given the make-up of the structures, it was decided that the Cintec system would be ideally suited. The instruction to
How the Cintec anchor works The Cintec system comprises a steel section in a mesh fabric sleeve, into which a specially developed cementitious grout is injected under pressure. The flexible sleeve of woven polyester restrains the flow and expands to about twice its normal diameter, moulding itself into
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