Bridge Key To Doncaster’s £8m Waterfront Regeneration

An exercise in value engineering has saved thousands of pounds and played its part in a major £8m landmark development that will seethe upgrade of Doncaster’s waterfront.

Network Rail is developing a new depot on Marshgate, next to Friar’s Gate Bridge, in order to create a major town centre base forits regional operations, currently spread across five sites in the town.

However, the bridge – a key point of access to the development area – failed its assessments and was deemed in need of strengthening.

Design Engineer, Ross Hardy, takes up the story: “We were faced with a double challenge. Initial designs showed strengthening work was required to the bridge’s underslung cross girders, however, the recommended method effectively reduced clearance between the water level and the lowest point of the bridge deck, which was not acceptable to all parties.

“Allied to that the overhead bracing, on top of the structure, also failed its assessment, and initial thinking was that steel ‘crucifix bracing’ – from above they look like a series of large metal ‘X’s’ spanning from left to right – should be used to give the structure renewed strength.”

HBPW was asked to come up with some alternative, innovative thinking.

“Rather than working with the existing underslung cross girders – the original drawings sought to add steel pieces to the old metal work but, in doing so, reduced the water-to-bridge clearance level – we opted for temporary works.

“These enabled us to support and completely replace the old cross girder hangers, avoiding the need for metal strengthening ‘plates’ and the consequential reduction in water-to-bridge height, a much better solution that was acceptable to all vested parties.”

New extra-strong horizontal sway beams running the length of the bridge were also added to the top of the structure, and the addition of height increasing steel stools paved the way for the ‘new’ bridge to take bigger and heavier vehicles.

“Instead of using Crucifix Bracing, which we knew would be a challenge to fit because it has to be craned into place pre-assembled and drilled at four corners, we opted for single fabricated steel strips – half of a cross if you like – running corner to corner and requiring drilling and fixing at just two points.”

This alternative engineering approach took time, material cost and effort out of the implementation process, and the bridge, once complete this summer, will be good for use by vehicles up to 40 tonnes across each of its two lanes.

Doncaster Council say the strengthening and renewal ofFriar’s Gate Bridge will help unlock wider commercial development in thesurrounding area and open up opportunities for further private sectorinvestment and regeneration.

The bridge works have been jointly funded by Network Rail and the SheffieldCity Region Investment Fund.