© Martin Bodman
TRACK EQUIPMENT & MAINTENANCE
160 years of service
The viaduct, built in 1852, carries the line across the tidal estuary of the River Loughor.
Majer explained: “It’s going to be a com- plete replacement – a new structure. We did a lot of studies on the existing one there, and because it’s wood and has had bits bolted it, engineering consultancy Cass Hayward, who did it first, said it just couldn’t be strong enough to support these two tracks. It was singled in the 1980s be- cause it was buckling.”
She continued: “We looked at doing an off-line solution, which would have been cheaper for us, because we’re not able to shut the railway. However, because of the rail alignment, and the fact there’s a road really close on the north side, and the cost of putting in new embankments, it’s had to be an on-line solution.
“We’re looking at pilings either side of the existing structure, as close as we can get them to it, creating a sort of ‘goalpost’, put- ting in cross-heads, and then putting in some temporary piles alongside the exist- ing structure. Then we’re going to build the new structure and launch it out adjacent to the existing one. We’ve got a rail closure in January 2013 when we’re going to be able to demolish the existing deck, and slide in the new deck, which will be adjacent, into position. That deck will have the track on it, ready to become the new structure.”
Benefits
A speed restriction is currently in force, with freight services only able to travel at 25mph, Majer said, which will be lifted once the new structure is in place.
She added: “That will be useful, but the main benefit is that the viaduct replace- ment allows the wider Welsh Assembly Government dual-tracking project to go ahead, and the benefits of that to be real- ised. The structure needed repair or re- placement, but the reason we’re doing it now, and replacing it, is this other project.”
Conservation plans
The viaduct has 18 spans of about 12 me- tres (40 feet) each. It was originally en- tirely timber, but has been successively re-decked by wrought-iron and then steel plate girders, though parts of the substruc- ture remain original, according to the Roy- al Commission on the Ancient & Historical Monuments of Wales. An opening span of swing-bridge type at the western end was
replaced by a fixed span during the nine- teenth century. It is the only surviving tim- ber viaduct designed by Brunel and Fletch- er, according to the Commission.
Majer said: “It’s a Grade-II listed structure. It was thought the structure was Brunel, but we managed to prove that although the piles that went into the estuary were done in Brunel’s time, the wooden trestles that form the substructure had been replaced over the years. It’s listed now as an ‘example of a tim- ber viaduct on a working railway’.
“We’ve put in our planning application now, and as part of that we’re proposing to leave two of the trestles in on the western side, and one on the eastern side, so peo- ple looking at the structure can see what would have been there before. We’re also planning to take two spans of the existing structure, with the trestles and the deck, and put up a little ‘monument’ on the west- ern side, on Network Rail land. People will be able to pull into an existing lay-by and look at that.”
That idea came from a local authority conser- vation officer, as Network Rail has been keen to involve them in order to find out what the councils concerned considered acceptable in terms of heritage and conservation.
Priority project
Sue Miles, co-ordinator of SWWITCH (the South West Wales Integrated Transport Consortium), a formal alliance of the four unitary authorities in the region, told RTM that combining the dual-tracking plans with the Loughor viaduct replacement would cut both costs and disruption.
She explained: “SWWITCH has been work- ing with the Welsh Government and Net- work Rail to secure the re-doubling of the rail line west of Swansea for sometime. The fact that the Loughor viaduct was due for replacement provided an ideal situation for a joint approach to the projects between Network Rail and the Assembly, thus re- ducing overall costs and disruption to pas- sengers.
“The re-doubling of the line is a priority in the SWWITCH Regional Transport Plan 2010-2015 as it is seen as critical to in- crease the resilience of the current service – and thus fewer delays for passengers – and to enable improved levels of service to be introduced in the future to serve growth in passenger numbers.
“SWWITCH believes the work will make rail a more viable and attractive transport option in south west Wales and encourage more multi-modal journeys in the longer term.”
Improvements
Alongside the dual-tracking of the line be- tween Cockett West Junction and Duffryn West Junction, which should allow two more trains an hour between Swansea and Llanelli, and one more an hour between Swansea and Carmarthen, there will also be station improvements at Gowerton. Network Rail promised a “bigger, accessi- ble and secure” station with two platforms – following the reinstatement of the dis- used eastbound platform – as well as a new DDA-compliant footbridge with ramps, real-time customer information system, CCTV and better lighting.
The signalling and crossing infrastructure at Duffryn will be upgraded to handle the dual-track railway, and alongside the ma- jor viaduct works, smaller scale upgrades will also improve bridges at Traffle Mill, Gypsy Cross and Rhosog.
Mark Langman, route managing director for Network Rail Wales, said: “The scheme promises to bring huge social economic benefits in south west Wales by improving capacity and connectivity to key employment centres such as Swansea, Llanelli, Carmarthen, Fishguard and Milford Haven. There will be an improved passenger experience with shorter journey times and better connections that will also encourage modal shift, potentially removing around 300,000 trips from road to rail and improving the green credentials of rail.”
FOR MORE INFORMATION Visit
www.networkrail.co.uk/wales rail technology magazine Dec/Jan 12 | 31
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