Engineers have completed the launch of a bridge deck weighing 1,620 tonnes over the Grand Union Canal at Longhole near Ufton in Warwickshire.

A 1.5-mile section of the Grand Union Canal was closed while the 130-metre-long steel deck was slid into position across a country road, the canal, and the canal towpath.

The operation began on Wednesday, 4th March, and was completed in time for the Grand Union Canal to reopen seven days ahead of schedule.

To manoeuvre the deck into position, engineers used ‘skid shoe methodology’, in which two giant hydraulic jacks propelled the deck forward at up to ten metres per hour.

To minimise friction, special pads coated in a Teflon-like material were placed underneath the deck.

At its peak, 40 engineers worked on the project, installing 34 piles at depths of up to 30 metres, two concrete piers, two abutments, and 37 precast planks on which the bridge deck rests.

To ensure the canal’s structural integrity, a new retaining wall, consisting of seven-metre-deep sheet piles, was built before construction of the viaduct started.

The Longhole viaduct is one kilometre from the north portal of HS2’s Long Itchington Wood Tunnel, and after exiting the tunnel, they pass through Ufton Wood to Longhole viaduct via the Welsh Road embankment.

During construction, vibration levels were monitored to ensure the integrity of the nearby Grade II listed Longhole Bridge, which crosses the Grand Union Canal.

The launch of the bridge deck was timed to ensure the closure of the canal took place before Friday, 13th March, when the canal reopens to public use.

In February, engineers finished constructing four parallel viaduct decks at a triangular intersection of the HS2 east of Birmingham.

Vicki Lee, Senior Project Manager at HS2 Ltd, commented that good progress had been made in this area over the last 12 months, with the completion of the Long Itchington Wood Tunnel and the deck slide over the Longhole viaduct.

There is still much work to do on the associated embankments and cuttings before track and power are installed.

“The team has put in a huge amount of work to prepare for the bridge installation and shown meticulous attention to detail throughout to protect the canal and nearby Grade II listed bridge. “I’m delighted we’ve been able to complete the works one week ahead of schedule, and thank the local community for their patience.”

Harry Toase, Balfour Beatty VINCI’s civil engineering lead for the project