River Nene

Refurbishment of 4 railway underbridges, including the Grade II listed ECM1/184 bridge, the oldest cast iron structure to still carry main line traffic in the world. This bridge is comprised of three similar 19m spans, each with six arch ribs. The four inner arch ribs effectively carry the tracks over the River Nene.

Works upon two of the four structures required a Christmas Day blockade; allowing the removal of the railway tracks to undertake essential repairs to the structure. All four bridges have had varying works carried out including, grit blasted, painted and strengthened with new waterproofing systems applied.

Schedule Of Works

• Works commenced upon the Grade II listed Cast iron bridge with the erection of a suspended scaffolding to allow suitable access to all areas followed by the encapsulation of the scaffold; providing protection to the surrounding environment and to enable control of the ambient conditions within the working area
• Once the structure was grit blasted and aluminium primed, a full structure survey was undertaken to determine the extent of the steelwork strengthening required. This varied from minor patch repairs to full lattice, gusset replacements and crown bolt replacement. It is worth noting that out of the many hundreds of repairs, each was individual and required its own unique template
• Following the extensive period of repairs the structure was re-blasted & primed prior to remediation of the heavily pitted girder webs using titanium putty. Protective coating works were undertaken to ensure a life expectancy of 25 years was achieved; old photos showed the bridge was originally painted in cream and brown and repainted green and brown in the 1980’s. Following consultation it was agreed that a return to the original colour would be the best option
• The 2014 Christmas Blockade works consisted of an immense collaborative effort between a number of contractors in order to strengthen and restore two adjacent structures within a short possession period. With the railway tracks removed, our works consisted of the removal of existing holding down steelwork, the installation of new holding down straps, the replacement of 76 fatigue cleats and 225m of new guard rails. Over the 4 day period we replaced 1,950 old rivets and installed 220 holding way beam bolts, 38 new steel transoms, 145m of rolled steel angle, 1,125 shim packers & 76 new steel tie bars
• The final bridge in the package, known as the intersection bridge due to it passing over the March to Ely lines, required the removal of the existing waterproofing system from the 125ft long steel deck. Garnet was selected as the blasting media; this environmentally inert material could ensure the SA2½ standard of cleanliness was achieved whilst being non-ferrous, would avoid operating the circuit within the overhead lines as the overhead lines remained live throughout the works with all works carried out to this bridge utilising line blockages with TCOD protection
• Once the bridge deck was prepared and cleaned an acrylic based waterproofing membrane known as Eliminator was applied at a thickness of 3,400 microns via airless spray. This was followed by 4-6mm of Flintag as an anti-slip coating system
• Further Steelwork strengthening was required upon this structure, including the replacement of truss mid-height brackets, the installation of 112 new steel plates to main girders and the filling of voids from the old drainage system no longer required, each was sealed using polysulphide sealant and finished with additional coating protection

Added Value

The Grade II listed cast iron structure refurbishment attracted a lot of national attention, especially catching the eye of the Institute of Civil Engineering board (ICE) which led to the project being awarded the only 2015 Historic Bridge & Infrastructure Award which was collected alongside Bam Nuttall, Network Rail & AECOM, along with our Managing Director Graham Moor & Senior Contracts Manager Shaun Marsden.