A development project to refurbish and repair St Julian’s Viaduct in the city of Newport, Gwent is well underway and is on schedule to complete by July 2014.
Initial works began on the scheme in January this year and involves an array of refurbishment, maintenance, civils and reparation works being undertaken by the onsite team.
The bridge was originally built in 1874 and a refurbishment and strengthening project was undertaken in the 1960’s; however since this scheme the bridge has deteriorated to a stage that it needs further work. The six month project is being undertaken by Network Rail in a bid to improve the structure which was built well over a century ago. The planning process began in 2013 main contractors Balfour Beatty became involved at this time.
The onsite team consisted of structural and civil engineers Tony Gee and Partners LLP who are based in Stonehouse, Gloucestershire, and SRK Scaffolding Limited who are based in Taunton, Somerset. SRK Scaffolding has enabled the onsite team gain access to the bridge and carry out the works. Heywood & Jackson have also been integral to the project and have undertaken the steelwork repairs and all the strengthening works to the bridge and piers.
KMAC Ltd have carried out all the civils and masonry works on the project including all the re-pointing of the stone masonry, stone piers, and addressing cracks in the abutments. DP Painting carried out all the painting on the bridge.
The project will see the main deck of the bridge strengthened, as it is currently substantially under strength, and new bracings will be installed on the piers. The viaduct carries two tracks over the River Usk and consists of four brick arches and four wrought iron lattice truss spans which include wrought iron cross girders and plate floors.
The tracks run on longitudinal timbers and the project has been undertaken with the intended aim of increasing the capacity of the bridge as much possible. During the works the impact on the waterways has been minimised as a large part of the works has been undertaken from the bridge level.
At the start of the project the team started works from the south embankment of the River Usk due to access restrictions. Access from the north bank was not possible and so the team started painting span one and two of the bridge back in April firstly and have recently completed works on this part of the structure. The team handed back to Network Rail in May and has so far completed 46% of the project. They are now set to undertake works on span three and four left to do and two other sets of piers in the water.
Throughout the project mariners have been kept abreast of the different works being undertaken on St Julian’s Viaduct. In order to complete the repair works underslung scaffolding had to be attached to the bridge and hung two metres below the structure. This was moved to different spans throughout the project and therefore mariners were made aware of the potential dangers posed by this equipment by the Associated British Ports South Wales branch whenever necessary.
In order to ensure safe passage for any vehicles passing under the bridge one of the middle two spans of the bridge was cleared at any given time. Passing underneath a span with scaffolding attached has been forbidden by ABP for mariner’s safety. From March onwards the onsite team erected a Pontoon platform around the piers and a safety boat was always in attendance on the river at high tides, again to ensure workers and mariner’s safety.
The team encountered difficulties during the project as the tidal range of the River Usk is tremendous and the team started works during the floods; therefore the river levels were even higher than usual. The team have ensured their works coincide with the tides as they dictate what areas can be worked on at which times. The onsite team has constructed an elaborate temporary work design for the floating pontoons in order to contend with the large tidal range, which can be up to 13 metres. This temporary platform acted as a robust working platform for the team to work off and also was secure enough to carry the heavy work equipment used form day to day.
When the river was at low tide the team tackled the works on the lower parts of the columns and at high tide worked at the top of the columns. The works program has been coordinated with the tides. As the bridge is four span works have had to be undertaken in a particular sequence; the main trusses have been strengthened primarily and then the underslung scaffolding was installed. The programme is due to complete by July.
The St Julian’s railway bridge is a crossing of the River Usk in Newport city in Gwent. The bridge carries the Welsh Marches Line across the river in a north-south direction; the line was originally opened in 1874 by the Pontypool, Caerleon and Newport Railway.
Main contractors Balfour Beatty have built up an extensive portfolio since their inception and so are well qualified to deal with this project. The firm is a world class infrastructure services business which operates across the infrastructure lifecycle over 80 countries. The firm operates in an array of industries including transportation, power and energy, water, commercial and social sectors.
Ravi Ramlagan, Site Agent, from Balfour Beatty said that during the project the team discovered that additional repairs were required that had not been previously factored into the initial budget. This impacted the cost and schedule of the works programme but Network Rail took the bridges needs into account and were able to provide funding for the other repairs.
Ravi said the work does have a large element of risk but Balfour Beatty try to minimise the risk by using competent operatives and a mobile elevated working platform on the pontoon, which allows them to reach further onto the bridge at low tide.
“It has been exciting to be involved in this project because you can see what the bridge looked like initially and see the finished project and it has made such a vast difference. The process is also quite humbling as well to look at the bridge and know it was built 140 years ago. To build such a large structure that long ago is impressive and would have been quite difficult to do. It is amazing to think of all the man hours involved in the projects in the past and the legacy that those workers left behind. We are simply trying to maintain the structure and keep it stable for another 100 years.”