As the world was wishing itself Happy Christmas recently, HBPW engineers might have been forgiven for getting butterflies as the rail division prepared for one of its biggest collective challenges to date.
Partners Paul Monaghan, Jon Livesey and Design Engineer, Ross Hardy, were put on standby in the run up to Christmas Eve, as Network Rail contractors prepared to take possession of three rail bridges and carry out essential improvement works.
Each of the three ‘blockades’ – usually a 56-hour period in which rail lines are legally closed so that vital work can done – commenced around midnight on December 24th and continued until December 27th.
But as Jon Livesey explained the triple possession was not something to be taken lightly.
“Personally, I have never had more than one blockade at any given time so I think it is fair to say that this was a big deal! We all had a slight feeling of apprehension because a bridge possession reconstruction not only works to a tight, inflexible deadline, but there’s so much that can, potentially, go wrong.”
But, all three were a complete success.
Crofton – A High Impact Job
The line closure at Doncaster Road in Crofton, Wakefield, was to facilitate the £3.7m upgrade of the railway bridge.
Built in 1880 the structure, which carries the Knottingley to Leeds line over the A638, had been repeatedly struck by high-sided vehicles over the years, resulting in structural damage and extensive delays to both the railway & road.
“The bridge was understrength and had effectively reached the end of its design life so consequently it needed reconstructing” said Jon. “Network Rail was obviously keen to minimise future bridge strikes and therefore the track has been lifted and the new twin U-deck is slimmer which improves the signed clearance by 0.3m.”
Cuffley – Hertfordshire’s £3.2m Makeover
Station Road bridge in Cuffley had also experienced vehicle impacts, but nothing like as badly as Crofton. There, NR was investing £3.2m in replacing the steel bridge deck, again with one of its standard twin U-decks.
The structure, originally built in 1907, carries the Hertford Loop Line, connecting communities into London and with the East Coast Main Line.
“We were initially asked to look at strengthening works to the bridge around five years ago. However, it quickly became apparent that the extent of work required wouldn’t be cost effective and that it would be better spent reconstructing the bridge to ensure reliable train journeys for future generations.
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“Both Crofton and Cuffley were installed using Self Propelled Mobile Transporters (SPMTs), a platform vehicle with a large array of wheels used to move huge objects, in our case new bridge decks. These enable the bridge to be reconstructed without relying on extremely large cranes which can be adversely affected by high winds. With the time constraints of the possession the SPMT’s help mitigate the weather risk. They are also a very impressive sight: at Crofton, at one point, there was over 600T of bridge rolling down the road!
“Fortunately, Paul Monaghan, Ross Hardy and myself were able to provide assistance from the comfort of our festive homes thanks to a few time-critical phone calls”.
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The Irchester ‘Bat’ Challenge
Here the festive race against time appeared in stark contrast to the two-year timeframe in which it took interested groups, environmentalists and Network Rail to facilitate the removal of protected nesting bats from the remnants of an old ‘marked-for-demolition’ station at Irchester.
“HBPW was among a string of professionals playing its part in the wider Midland Main Line Upgrade, which has seen an additional line constructed between Bedford and Kettering, as well as the electrification of the line to Corby.
“The Irchester overbridge – also known as Station Road – had been identified for a range of demolition and / or upgrade work to pave the way for electric trains and, two years ago, we oversaw the demolition and reconstruction of the bridge deck crossing the ‘slow lines’.
“However, whilst we were able to demolish and re-build Span four of the bridge as part of the project, we were unable to proceed with demolition of the nearby disused station building due to the discovery of a significant bat roost.”
And there began a two-year countdown involving conservationists and interested groups.
“In was a dual conundrum,” said Paul. “On the one hand we had bats – a temporary block to the old station being demolished – while on the other the structure desperately needed to come down because it not only needed routine maintenance, despite being disused, but it also featured a ‘credible standing surface’, a key danger in an electrified rail environment that needed to be removed.”
But, with all the necessary licences to sympathetically remove and relocate the bats from their home to new roosts in nearby woodlands and a void within the existing bridge masonry, demolition work was able to begin in earnest over the Christmas period.
“In Irchester we had just 52 hours in which to raze the structure to the ground and move a veritable 800 tonnes ‘mountain’ of brickwork.
“Overall it has been an extremely complex affair – largely led by the bat situation – however, we eventually got on site over Christmas and brought everything to a successful conclusion.
“There is no doubt that this is a hat-trick of which the entire rail team at HBPW can be proud. Definitely one for the company CV!”