Newland Bridge, A645

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  • Construction
  • Instrumentation and Monitoring

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Jake Kaufman

Business Development - Monitoring

01942 446150

Challenge

Newland Bridge is a three span composite steel and concrete structure carrying two lanes of the A645 over the River Aire, constructed in 1991.

The embankment approaches to the structure have suffered from up to 800mm of settlement since construction. This was an ongoing road maintenance problem, but has also impacted the adjacent bridge structure. The abutments of which are being pushed toward the deck by ground movement, such that longitudinally free bearings on the west end of the deck are beyond their limits and the deck is subject to a propping force of ~4MN.

With forces and movements of this magnitude imposed on the structure, accurate, reliable, real-time information was essential for engineers to monitor the effect of the repair and deck repositioning works.

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Solution

A longitudinal and transverse hydraulic jacking system was developed jointly by Mabey and Arup. The longitudinal hydraulic jacks were preloaded to 1 MN each - 2 MN at the end of each deck. The loads in the longitudinal jacks and strain gauges were continually monitored, ensuring that propping force was controlled. The embankment mass could then be removed, allowing the forces in the abutments to return to equilibrium.

In order to reinstate the articulation of the deck and allow the abutments to move to equilibrium, it was necessary to reconstruct the west abutment curtain wall, reopening the movement joint that had closed by ~120mm. The jacking system, manufactured and installed by Ekspan, was used to lift the bridge vertically in order to replace the bearings at the piers and abutments, during which time the longitudinal and transverse jacks maintained the location of the deck. An additional operation was required to move the deck to an optimal position, considering pier movement and residual long term settlement.

The measurement of the bridge’s position and performance was achieved through the unique combination of measuring devices and techniques linked together using bespoke software to provide accuracies of greater than 0.1mm. Data from the sensors was conditioned through a series of calculations and presented to the engineering team in real time through a web interface - Mabey LIVEsite.

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Result

The combined system successfully kept the bridge within the prescribed tolerances throughout the project, with no out of tolerance distress. LIVEsite offered consistent, accurate information throughout the operation, providing assurance for the contractor, engineer and asset owner.

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