Newcastle's Howard Street Bridge demolished with time to spare

UK demolition contractor Thompsons of Prudhoe has demolished Newcastle's Howard Street Bridge in just 30 hours.

Demolished as part of the New Tyne Crossing project in Newcastle, UK the existing Howard Street Bridge was situated over the southern exit of The Tyne Tunnel.

A 20 m-long, one way spanning, reinforced concrete pinned portal frame bridge supported by concrete foundation piles, its deck varied in thickness from 686 mm at the centre to 1067 mm at the supports.

The work was completed during a 36-hour road closure to the A19 dual carriageway, with the handover back to Thompson's client, Bouygues Travaux Publics, achieved six hours earlier than originally scheduled.

The job was completed by two teams of 14, working 12-hour shifts with an array of equipment including Komatsu excavators from 20 to 75 tonnes, the largest machine being fitted a 15 m high-reach boom.

The work included highway protection measures, earthworks to facilitate removal of the abutment, pre-weakening of bridge deck, demolition of the bridge deck, abutments and wing walls, removal of sheet piles and removal of approximately 200 loads of concrete and 150 loads of soil, or 3000 tonnes in total, within the closure period.

According to Thompson's contracts manager Nick Shilling the most difficult part of the demolition was the West abutment.

"The concrete was directly up against the soil embankment and therefore we could not attack it from both sides, and the concrete was just 'pushing' into the bank-side as opposed to breaking off.

That and the close proximity of the new structure, in places just 500 mm off the existing structure, were the main problems facing us.

"But we overcame these by using the earthworks behind the abutment to free up the structure," said Mr Shilling.

Project background

The New Tyne Crossing Project comprises:

• Construction of a second, 1.6 km-long vehicle tunnel under the River Tyne
• Full refurbishment of the existing vehicle tunnel
• Redesigned southern interchange at the entrance to the existing vehicle tunnel
• Development of a new tolls plaza on the new northern approach to the vehicle tunnel

TT2 was appointed in November 2007 as Concessionaire to design, build, part finance and operate the new vehicle tunnel and other developments associated with the New Tyne Crossing project, and to operate all Tyne Tunnels until 2037. It is one of the largest transport infrastructure projects currently under construction in the UK.

Work to prepare the site began in February 2008 and construction of the new tunnel began in October 2008. Work on the second vehicle tunnel is due for completion in February 2011, at which point the existing tunnel will close for extensive refurbishment.

The construction phase of the project is expected to be completed in December 2011 when both tunnels will be open to traffic.

Concessionaire

The concession contract worth € 500 million was granted for a period of 30 years to the TT2 consortium, which consists of Bouygues Travaux Publics and also the financial institutions HSBC Infrastructure Fund II and Bank of Scotland Corporate.

The concession, which officially started on 1 February 2008, includes the delivery of the second Tyne crossing tunnel scheme and also the operation and maintenance of all the tunnels under the river, including pedestrian and cycle tunnels.

The TT2 consortium will also provide about 65% of the investment that is required over the 30-year life of the concession.