Displaying items by tag: Bridges
Client: Essex Highways
This project included the removal of temporary supports to install a permanent reinforced concrete pedestrian underpass under the existing road bridge which carries the B1389 Newland Street/Colchester Road.
Originally constructed in 1842, Catholic Bridge consists of eight cast iron beams with brick jack arches. Strengthening works were undertaken with the installation of trestle supports during the Second World War and a second set of supports were installed in the 1990’s.
In 2014, three of the cast iron beams were identified as unsafe during a support inspection and as a result, temporary supports were installed to keep the bridge open to traffic.
Throughout this project Jackson used real time monitoring on the existing cast iron beams to ensure the stability of the live bridge 24/7.
To allow space to construct the proposed underpass, the two sets of existing temporary supports needed to be removed, however, the existing structure still required additional support. This was achieved by installing portal frames running parallel with the cast iron beams but situated central to each jack arch.
The position of the concrete foundations required for the new support system clashed with existing foundations. To allow the new foundations to be constructed, further temporary supports were installed immediately under the cast iron beams. These were supported on the abutment walls and by the original trestle supports. This then allowed, during a weekend road closure, removal of the second trestle support and construction of the new concrete foundations. These had to be reinstalled before the road was reopened to traffic on Monday morning.
Due to uncertainty regarding the stability of the existing abutments the excavation for the foundations was spilt into three sections along the abutments. This required careful planning as access was restricted. Three reinforcement cages were preassembled and fixed within three sided shutters which were through bolted to facilitate lifting. These were to be the first three sections of concrete to be placed following excavation during the weekend.
Jackson also reduced the weekend shift by 25% through the use of a vacuum excavator (Vac-Ex). The Vac-Ex was used to excavate under the bridge in preparation for new concrete foundations to support a new temporary steel portal frame. This method provided a safer, lower risk alternative to traditional excavation techniques, as there is no need for additional excavator movements and dumpers. Doing so, the team were able to save 12 contract hours and work more efficiently in constricted areas.
Once the excavation was complete, the concrete foundations for the temporary steel portal frame were poured using volumetric mixers. The concrete was allowed to cure for 12 hours before replacing the second set of temporary supports and the road opened to traffic on Monday morning.
Having completed the foundations the portal frames were then installed by threading the steelwork into the existing temporary supports. When all of the frames, support beams and stools were complete, nine portal frames were synchronously jacked during a further road closure. The jacking ensured that the portal frames now carried the load. This allowed the team to remove the existing temporary works and create space to install the permanent reinforced concrete pedestrian underpass.
On completion of the main section of the underpass structure under the footprint of the original bridge shuttering was erected to the remaining void between the two structures. This enable the annulus to be filled with foamed concrete placing it in four layers. To ensure the void was completely filled the concrete was poured through ‘letter boxes’ in the shutters and using sacrificial pipework. The crown of the jack arch barrels were filled with grout placed from the road above.
The ‘ends’ were then closed off with reinforced concrete wingwalls which extended to support the parapet walls of the original structure. The wingwalls were then faced with brickwork sympathetic to the existing facing bricks.
Anti-vandal lighting units have been fitted and all new surfaces coated with anti-graffiti paint.
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Client: Rochester Bridge Trust
Built in 1914, Rochester Old Bridge is a Grade II Listed Structure. Jackson was contracted to carry out refurbishment works to the bridge to improve the appearance of the upstream section, by de-constructing, blasting, coating and reassembling the balustrade, and laying new paving to the footway.
Crucially, the works also included replacing corroded structural steel balustrade posts and the supporting edge-stiffener channel, a pre-fabricated ‘C’ section.
The project involved work to three spans of the bridge, and a cantilever scaffold was required over the river to gain access. Due to its Grade II listing, all works were carried out in accordance with the requirements of English Heritage.
Client: North Yorkshire Council
This project involved the construction of a roundabout in place of a staggered cross roads at the A19/A63 junction in Barlby, North Yorkshire. The A19 carries over 33,000 vehicles at this location every day and the roundabout was designed to improve safety for right turners and also decrease speeds on the A19 to aid motorists coming from the A63.
The original programme for the project was 22 weeks – but by imposing a full road closure, and working seven days a week, the team managed to complete the project in 10 weeks, thus greatly reducing the impact of the project on the local community.
Without a closure construction could have taken as long as 36 weeks.
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Client: Olympic Delivery Authority
Jackson was included on the ODA’s Civil Engineering works framework, and carried out several enabling projects for the Olympic Games.
These included earthworks and foundations for both the warm-up track and the Waterpolo Arena in the Olympic Park at Stratford, the construction of a pedestrian footbridge at the rowing venue at Eton Dorney, and the provision of several ‘Park and Ride’ facilities across the country.
The project we’re most proud of however, is the floating walkway we constructed across Royal Victoria Dock to provide access for spectators to the ExCel Exhibition Centre. The walkway was made from floating shipping containers, linked together and anchored to the dock bed - it was one of our more unconventional designs, but the end product looked the business.
Client: Connect Plus
The QEII Bridge at Dartford carries 150,000 vehicles per day and is one of the busiest sections of road in the world.
Jackson recently replaced the six original multi element expansion joints, which were installed when the bridge was built in 1991.
Due to the sheer volume of traffic that relies on the Dartford Crossing every day, the team had to devise a clever method which kept the bridge open.
The solution was a bespoke designed and built temporary expansion joint, which could be installed during a single night closure over the existing joint. Work to remove the old joint was then carried out during the day, from the underside of the bridge. The new joint was then installed, again, during a single night closure which meant that disruption to traffic was kept to an absolute minimum.
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Client: Kent County Council
Jackson was contracted to build a 1.9Km relief road around Sittingbourne in Kent to ease traffic congestion in the town.
The carriageway was constructed across open fields, a heritage railway and service corridor, a closed landfill site and Milton Creek. The route required the construction of two steel and concrete composite bridges over the railway line and Milton Creek.
Client: EM Highways (for TFL)
Spring Lane Bridge is a road/pedestrian bridge in the centre of Croydon. It is a busy traffic route, and serves several vital bus routes. Due to structural issues, the bridge had to be closed to HGV’s and buses in 2010 and vital bus routes diverted around the bridge.
These lengthy diversions significantly increased public transport running costs, so in Spring 2014, Jackson began work to reconstruct the bridge.
The project presented a number of challenges. Firstly, being situated in a built up area, surrounded by residential and commercial properties, and with a live tramline running underneath, and a pedestrian footway running across the bridge which could not be diverted, the project required thorough contact, communication and co-ordination with many stakeholders, particularly London Tramlink.
The project also had various time constraints, one of the most important being the 9 day blockade period during which the tram link was shut down, and critical demolition and new bridge construction operations could take place. Despite the project starting almost 6 weeks behind schedule, the project team managed to achieve critical works in line with the blockade, and no possession works overran at any stage.