Clifton Scannell Emerson Associates (CSEA) are appointed as Lead Consultant. Employers Representative and PSDP for the statutory approval, contract documentation and construction supervision of a proposed cycle/pedestrian bridge, in the form of a cantilever boardwalk, at 'New Bridge', Athlumney Street, Navan, Co. Meath. The scheme involves the following: -
- Construction of new 3.5metre wide cantilever cycle/pedestrian bridge over the River Boyne;
- The construction of new shared cyclist/pedestrian surface, of varying width due to existing constraints, along Athlumney Street and the existing bridge;
- The installation of new wearing course to road surface with associated line markings and signage.
The existing masonry arch bridge, 'New Bridge', is a protected structure constructed in 1756. It is a 6-span masonry arch bridge connecting Athlumney to the east bank of the River Boyne with Navan on the west bank. The bridge carries a 7.0metre wide single-lane carriageway, with 1.0metre wide footpaths on each side, over the River Boyne.
The large volumes of traffic on the bridge coupled with the existing narrow footpaths has driven the need for a new bridge to improve pedestrian and cyclist safety and accessibility.
As part of feasbility studies, CSEA have completed cultural heritage studies and ecological asssessments for the site location.
As part of the cultural heritage and environmental assessments, a number of structural defects were noted with the existing bridge including crack in the arch barrels, seperation of spandrel panels and extensive mortar loss. CSEA, bringing their 'EIRSPAN' experience to the fore, initiated a Special Inspection (SI) to examine the bridge further which included an underwater dive survey to ascertain defects below the water line, including scour. The SI indicated minor scour damage below the water line and susbstantial cracking throughout the bridge.
Remedial works including horizontal ties to the spandrels, saddling slabs over the existing arches and repointing throughout have been detailed by CSEA and are included within the contract documentation.
The structural form of the proposed bridge will consist of cantilever steel beams protruding through the upstream spandrel wall, at each existing pier location supported on sleeved pile foundations driven through the existing bridge structure - all remedial works will be completed prior to commencement of the proposed bridge.