Design, Bridge Deck Replacement, Temporary Works
Completed in 2017, the new bridge at Maerdy forms part of the Great Western Electrification programme and facilitates the installation of overhead electrified wires through the area by the removal and reconstruction on the same footprint of the overline road bridge with improved vertical clearances.
The existing bridge structure was a half-through steel deck comprising longitudinal jack arches supported on steel cross girders and main longitudinal girders.
The existing overbridge supporting a farm track over the four track South Wales Main Line had substandard clearance and required replacement in order to achieve minimum OLE clearance of 5150mm as agreed by NWR OLE Engineers.
An Option Selection Report undertaken by Crouch Waterfall in November 2014 identified that the existing bridge should be replaced with a bridge deck comprising of pre-cast and pre-stressed concrete beams with an insitu concrete infill. To achieve the required headroom gauge clearance the level of the access track required raising and reprofiling over the new deck.
The new bridge deck has a clear span of 15.5m and a deck width of 5m. Temporary Works designs also completed by Crouch Waterfall for this scheme included detailed demolition sequence, track protection design and crane outrigger support design for installation of precast units.