Edinburgh Council is looking for a contractor to carry out a £22M package of vital repairs to a city centre bridge.
Work to carry out repairs on the city’s North Bridge is expected to be approved at the end of March, with work set to start in summer 2018 and complete in Autumn 2020.
The bridge is 120 years old and has been found to be in a poor structural condition.
The package of works will include strengthening and structural steelwork repairs, grit blasting and repainting of the structural steelwork, repairs to the concrete deck soffit and replacement of expansion joints.
A potential £7.8M package of enhancements work to be carried out at the same time as the repair work, is set to go to public consultation over the summer.
The enhancement work could include widening footpaths, replacing kerbs, resurfacing of the carriageway and major improvements to the North Bridge / Princess Street / Waterloo Place junction for cyclists and pedestrians.
A report prepared for the council warned that weight restrictions would have to be put in place if work were not carried out on the bridge. The report said little maintenance work had been done on the bridge in its 120-year history.
“Calculations have shown the bridge, in its current condition, to be nearing the limit of its load carrying capacity,” the report said. “If the necessary work is not undertaken soon it may be necessary to impose a weight restriction on the bridge which could restrict its use by public transport and freight traffic.”
The report noted a number of incidents over the last three years, including loose material falling from the underside and the façade of the bridge. As part of emergency works, netting has been installed under the bridge to protect vulnerable areas underneath.
An inspection in 2014 revealed heavily corroded steelwork, easily crumbling concrete and parts of the cast iron decorative façade were also corroded. At this time, two load bearing beams were repaired and the bridge made safe after they were found to be heavily corroded.
Repair work on the bridge will be complicated by the need to carry out the works over a live railway, added the report.
It said the duration of the construction period would be heavily dictated by the availability of railway possessions. It warned that these would be restricted to short overnight periods typically only two hours long.
“Should Network Rail cancel or fail to make railway possessions available this could greatly decrease the productivity of the contractor and greatly increase the duration and cost of the project,” it said.
Work to repair the bridge is mainly restricted to the underside of the structure. Once work is carried out, the bridge will be able to carry vehicles up to 44t.
Funding for the repairs was confirmed last week with an £12M set aside in addition to the £10M already promised.
Preparatory work on the bridge was carried out by Balfour Beatty.