Snowbridge
Glasgow, Scotland, U.K.

Hidden in the tranquil gardens of Kelvin Grove Park Glasgow, Scotland. The Snowbridge was thought by many to have gracefully retired into obscutiry. Its past glory of being the main means of disposing of the accumulated snow from the entire main thoroughfares of Glasgow had been superseded decades before by mechanical loaders.

With its retirement, it suffered like most obsolete structures with neglect and lack of maintenance due to the low priority it rated in the financial bids.

In 1987, CINTEC was asked to provide an estimate to rectify the many years of neglect. Following a complete survey and report from the Engineers Ove Arup and Partners, a comprehensive maintenance and anchoring scheme was presented to the City Council to bring the structure to a safe condition.

The scheme principally provided for the introduction of square hollow section stainless steel anchors size 30x30x3, 20x20x2, 15x15x1.5 in lengths from 500mm to 5000mm to the voussoirs and intrados of the arches and spandrel walls. The drilling chosen was wet diamond drilling with core retention to the natural stone structure. This provided that desired drilling accuracy and the need to reduce the vibration to a minimum in the fragile structure.

The proposals were kept in abeyance for several years before work commenced. Indeed, serious consideration was given to demolish the whole structure until it was found to contain optical telecommunications between the UK and the USA.

ROYAL BORDER BRIDGE, ENGLAND, U.K.

Royal Border Bridge, carrying London-Edinburgh mainline train. Photo: Mel Holley ©

As part of Railtrack's major programme of repair and refurbishment of the land-based arches, work was authorised on numbers 1-15 of the Royal Border Railway Bridge. The bridge carries the main Inter-City East Coast rail line between Edinburgh (Waverley Street) and London (King's Cross). George Stephenson's magnificent 28-arch, 128 feet high viaduct spans the tidal estuary of the River Tweed between Berwick and Tweedmouth, two and a half miles south of the Anglo-Scottish border. Queen Victoria and Prince Albert opened the 2160 feet long bridge in 1850; the structure will celebrate its 150th Anniversary at the Millennium. The project was complicated by both environmental and technical factors.

Green nylon based Debri-Mesh surrounded the main work areas to contain dust and debris from the drilling which, if uncontained, would cause environmental problems to the residents of the 36-house Riverdene Estate lying directly below the bridge. The covering material also provided a degree of shelter from the strong prevailing winds which blow eastwards down the Tweed River valley.

Furthermore, certain areas of the 61'6" span brick arches provided roosting areas for galleries of bats and, because they are a "protected species", provision had to be made to keep the bats' areas. The ornamental stone-work which forms the top parapet of the viaduct, is also a nesting site for House Martins; also in 1996 a pair of Kestrels were observed nesting under one of the electric catenary poles.

WORCESTER VIADUCT

Worcester Viaduct comprises of sixty-five brickwork arches rising from approximately two-storey height near the railway station, to over three-storey height as it approaches the river. Lack of of proper draining within the arch had led to the spandrel walls being forced away from the intrados arch with  longitudinal cracks close to the longitudinal edges of the bridge. Water penetration had also contributed to cracking at the springing of some spans and delamination of external parts of some columns. These problems had been exacerbated by weathering, particularly freezing and thawing. Previous attempts to restore the structural integrity were evident, but had proved ineffective.

Transverse 30 m x 30 mm x 3 mm SHS stainless steel WSA anchors were installed to restore the integrity of the spandrel wall/intrados arch connection at approximately 750mm centre-to-centre and alternate lengths of 2.0m and 2.5m. Stitching anchors were then angled across longitudinal cracks to restore structural integrity and the cracks were then filled. Transverse and diagonal stitching anchors, type RWT 15 x 15 x 1.5 SHS stainless steel, were installed to restore the strength of the delaminated columns and the cracks filled. Drainage holes were drilled through the intrados and plastic pipes installed to relieve the existing water pressure. To date five spans have been renovated using the Cintec system and further spans will be renovated as part of an ongoing maintenance programme.

FENCHURCH STREET RAIL STATION, LONDON, U.K.

Cantilever Signal System                            Viaduct

Fenchurch Street Station is one of London's busiest rail stations; it is the start point and terminus for the main tracks from the South of the U.K. to London. The construction itself is a remarkable example of Victorian 'railway' Architecture and was built at the height of rail travel era. The tracks carrying the service to the station travel over a Victorian Viaduct, comprising a series of arches. These arches support the cantilever system of signalling that guide trains to and from the station. The structure is a large steel gallows extending out over the track, with the signalling system suspended from it. The engineer had to recognise that any work on the structure had to address the problem of a live track running overhead.

  The torqueing of the anchors

The Problem

The assembling and installation of a compression anchor

A system was required to secure the gallows to the bridge arches; in their preliminary planning, Railtrack anticipated a shut down of the tracks for 6 weeks. Such a closure would mean a chaotic time table, irate passengers and a loss of revenue. The CINTEC Anchoring System proposal provided a solution that would require only 2 days of rail shut down

FENCHURCH STREET RAIL STATION, LONDON, U.K.

Foundation details of anchor arrangement to signal canitlever for British Railways at Fenchurch Street Station London

In shear

The Solution

The proposed solution involved three CINTEC Anchor types. The central one was a compression anchor of stainless steel comprising a 32mm shell rebar inside a 114 x 6.3 CHS installed in a 200mm hole, 8000mm deep, at an angle of 30 degrees to the horizontal. Below it was a tension anchor, comprising a In tension solid stainless steel body, 12m x 25mm installed in a 50mm drilled hole, and attached to the gantry support to prevent any rotation. Two smaller shear anchors 20mm x 800mm were similarly installed to complete the support. Load tests were carried out, with the placing of a 20m steel beam in position.

As a result of the use of a CINTEC installation, disruption was reduced from 6 weeks to 2 days together with a 50% saving on the original budget Railtrack had allocated to the project.