Bridge replacements have been featured in the rail engineer on a number of occasions. Usually these reports cover the most interesting examples of this work, as many are simply routine. New bridge arrives by road – old bridge is lifted out – new bridge is lifted in – old bridge is taken away. It’s been done in under eight hours, although a lot of preparation work goes on in advance.

However, what happens when the new bridge can’t be lifted in from the road, as there is no road access?

Dunblane difficulty

That is just what happened recently at Dunblane in central Scotland. As part of the preparatory works for EGIP, the Edinburgh-Glasgow Improvement Programme, the Bridgend footbridge near Caledonian Place was found to be foul of the proposed electrification.

Built in the nineteenth century, it was not practical to raise the existing bridge due to its dilapidated condition, nor was it possible to lower the track. The best solution was deemed to be its complete replacement. To this end, BAM Nuttall Ltd was appointed as principal contractor and work started on 2 April.

Day shift working accounted for most of the preliminary work. Over the weekend of 28/29 April, the concrete supports for the bridge were prepared by sawing and other techniques, ready for the actual bridge replacement the following weekend.

However, the complication was that there was no easy access which could be used to bring in the new bridge, and there was nowhere to site a road crane to do the lifting. It would all have to be done from the railway itself.

Plans were made to bring the bridge to the nearby station yard. Specialist plant company TRAC Engineering, based near Glasgow, were contracted to move the bridge from there to the work site.

Novel proposal

After considering the problem, TRAC’s proposal in consultation with BAM Nuttall was to move the bridge using a short train – with a difference. TRAC possesses a road-rail shunter derived from a Mercedes Unimog. Ballasted up to a gross vehicle weight of 12 tonnes, this shunter can propel up to six wagons with a total gross weight of 300 tonnes.

The shunter and five flat wagons duly arrived on site in the yard at Dunblane station, ready for a 29 hour possession commencing at 22:00 on Saturday 29 April. Two cranes were needed, a road crane from Ainscough to operate at the station end of the site, and a Kirow rail crane from Volker Rail to do the lifting at the bridge end.

At the appointed time, around 6am Sunday morning, the TRAC train departed for the bridge, where the Kirow lifted the old structure, weighing approximately 25 tonnes, from its seating and deposited it carefully along the length of the five small trucks. Once strapped down, the novel train departed for the short journey to the station and the road crane removed the old bridge to the yard.

Murdo Maclean, TRAC project manager, oversaw the reloading of his train, this time with two concrete cill units each weighing nine tonnes. These would be the spacer pieces so that the replacement bridge would sit higher than the original, allowing room for the OLE underneath. The cills were delivered to the work site and lifted into place about nine hours after the old bridge had come out, once the work to prepare their seatings was complete.

The now-empty train returned to the station yard where the smart new bridge was waiting on a low loader, and this was lifted onto the five wagons ready to be carried back to its new location.

At around 8pm on Sunday evening came the most precise part of the whole operation, as the Kirow had to lift the 15-tonne bridge from the wagons, swing it through ninety degrees and lower it precisely into place on top of the new plinths. However, no snags were encountered and everything went smoothly.

After that, it was just a question of placing the old bridge onto the low loader to be taken away, removing TRAC’s small train from the railway, and packing up the road and rail cranes. Everything was successfully carried out within the 29 hours allocated to the possession, and the railway returned to operational service on time.

John Edelsten, BAM Nuttall’s project manager was happy with the service provided by TRAC, complimenting both the site organisation and the personnel involved. With more bridge work being needed on the EGIP project, it shouldn’t be long before TRAC’s little work train is out again.