To facilitate the electrification of the South Wales Main Line numerous bridges are being demolished and rebuilt to provide clearance for the new OLE. Andun were appointed by
Forshaw Demolition to provide Engineering services for two bridge demolition jobs.
The Western Valley Intersection Bridge was located just outside Newport and spanned the South Wales Main Line (SWML). The bridge was initially constructed in 1849 and was later extended to span the newly four tracked SWML. The bridges were constructed to carry rail lines over the SWML. The bridge had a significant (40 degree) skew.
The two spans were of contrasting construction, with the original deck consisting of a ballasted steel deck spanning between steel beams and the edge plate girders. The later deck consisted of concrete encased steel beams spanning from abutment to abutment.
Using As-built drawings and SI obtained onsite during a night possession, a 3D model of both the bridges was created. This model was then utilised in the production of a demolition sequence for the bridge, which clearly demonstrated the intended method to all involved.
Full engineering assessment of the demolition sequence was undertaken to demonstrate to all parties (Carillion Rail and Network Rail) that the works could be completed safely, and F002/03 was submitted for the works. Andun also carried out category two design checks for the scheme.
Trow Road Bridge
Trow road bridge carried a road over the 4 track SWML. The bridge was a plate girder bridge, consisting of transverse beams with brick jack arches spanning between them. A 3D model of the bridge was constructed, and 3D sequence drawings were provided to show the intended demolition sequence. Full engineering assessment was undertaken and F002/03 was submitted. Both bridges were demolished without incident over Christmas 2014. Andun received a letter of thanks from Carillion Rail for our works on the scheme.