Tony Gee was commissioned to design a replacement structure for an existing rail overbridge, which provided the only route of access between a farmers land.
The original structure comprised longitudinal steel girders with a transversely spanning timber deck and metal parapet. The structure was in a poor condition and the capacity was limited to 3T.
In addition the site was located in an area subject to extensive historic coal mining at shallow depth. The original abutments indicated signs of distress, potentially due to ground settlement caused by coal workings.
Tony Gee developed a weathering steel composite solution with a pre-cast stringcourse, 2no. pairs of 40m long girders were lifted into place with the stringcourse, parapet and permanent formwork in place. This allowed for the beams to be lifted with edge protection in place and reduce the overall construction programme.
The pair of girders were formed from two pieces, as delivery to site was limited to a maximum length of 25m. The two pairs were lifted into place, spliced and an in-situ section cast to complete the stringcourse.
The new substructures were formed from stacked modular units, sized to suit the lifting capacity of the 1200T crane. The original superstructure was also removed during this weekend’s works. The scheme was delivered in tight time schemes through close collaboration with Murphy, Network Rail and the Esher CAT2 check team. We provided support throughout the construction phase including attendance at the trial erection.