Replacement Bridge Over Railway Line
These works involved the design and construction and the renewal and replacement of the superstructure to East Pastures Bridge. The structure carried a private road which is used by the public over the Saltburn West to Boulby Potash Mine line and due to dilapidation there was a weight restriction imposed upon the bridge.
The original substructure consisted of masonry abutments and wing walls, pilasters and wing wall parapet ends of masonry construction in large dressed sandstone blocks. The original bridge consisted of a masonry arch but this has been replaced by steel RSJ’s with timber decking and timber fencing parapets. It was proposed to demolish the existing deck and then to replace with 5no. pre-cast pre-stressed solid box concrete beams with shear key stitch connections.
Precast stitch caps will be installed onto the stitch to enable waterproofing to be installed immediately following insitu reinforced concrete stitching between pre-cast units of the deck. The outer beams are to have reinforced concrete parapet plinths cast to accommodate the proposed parapet system. The new deck was to be seated on new precast concrete cill units with elastomeric strip bearings and stainless steel dowels. The highway is reinstated to a similar vertical alignment as the existing with dense asphalt concrete surfacing, minimum thickness to be 120mm. Parapets were a proprietary system providing N2 containment. These were aligned with reconstructed and raised wing wall parapet built from stone to match the existing walls.
Originally the works were to be constructed during one long weekend disruptive possession with no contingency float time. Following discussions with the Network Rail Project Team the works were reprogrammed to be carried out over two 29 hour “white period” possessions on successive weekends with bridge dismantling, demolition, abutment support installation and preparation works in the first weekend and the new bridge installation in the second.
This effectively reduced the risk profile of the works by making them less prone to weather delays (wind was critical for crane lifts) and allowing the main crane lifts and selected activities, such as scaffolding, to be planned for daylight hours. In addition to reducing safety and programme risks, this two possession strategy had the additional advantages of enabling build quality and reducing the risk of impact on the Freight Operating Companies using the line due to programme delay as any preparation works for receiving the new bridge deck identified during dismantling and demolition could be carried out without time constraint in the week between possessions.
Replacement Bridge over Railway Line
|Location:||North Skelton, near Middlesbrough|
|Contract Value:||£260,000 approx.|
|Contract Period:||On site works done over 2nr weekend possessions|