CITYLINK TULLA WIDENING - BULLA RD TO MELBOURNE AIRPORT
CityLink Tulla Widening - Bulla Rd to Melbourne Airport
The $1.3 billion CityLink Tullamarine Freeway Widening project upgraded approximately 24km of freeway from Melbourne city to Tullamarine Airport. The Mickleham Road Bridge Overpass strengthening and widening works is one component of this large project. To ensure these works did not damage the prestressing strands in the bridge beams, Ground Penetrating Radar (GPR) scanning was employed to accurately locate the positions of the ducting. Infracorr was engaged to perform the GPR works, employing a 3 stage approach.
PROJECT HIGHLIGHTS• $1.3 billion project strengthening several bridge structures
• Strengthening works involved drilling thousands of holes through the beams, potentially damaging several prestressing strands embedded in each beam
• GPR scanning with a bespoke testing jig ensured no strands were damaged in the drilling of more than 6,000 holes
• All testing and construction works were performed with the bridge structures remaining open
• 3-Stage process, with completion of works due in 2018
The project design drawings detailed the locations where intended holes would be drilled. Infracorr encountered the following challenges:• Any intersection with the bridge’s prestressing cables during drilling would require closure of the bridge to traffic, causing major inconvenience to the public and major costs for Lendlease.
• An onsite scanning trial determined that scanning along the surface profile of the bridge beam would not be possible with traditional scanning equipment.
• Ensuring scanning works coordinate with scaffolding, scissor lift and drilling contractors.
To address these challenges, Infracorr devised the following solutions:• A close, consultative approach with Lendlease, that ensured all parties’ specific requirements were understood, reviewed, refined and the resulting testing procedure was improved. • The manufacture of project specific ‘jigs’ to extend the capabilities of the GPR equipment when scanning the various beam surface profiles. • Effective communication with LendLease ensured rapid mobilisation when scanning was required. • Appropriately trained and skilled additional Infracorr consultants supplemented the scanning team as and when required to ensure Lendlease’s program was not compromised. RESULTS
Some of the more significant achievements that Infracorr accomplished were:• The bespoke ‘jigs’, designed and manufactured by Infracorr, allowed accurate and efficient determination of prestressing cables, enabling holes to be drilled with confidence. • The GPR scanning by Infracorr resulted in not one single prestressing strand being intersected during the drilling of over 6000 holes through the bridge beams. • Infracorr’s rapid response to the scanning works and increasing the testing resources as and when required, eliminated any unnecessary program delays and costs to LendLease. • The bridge remained open to traffic throughout the duration of the strengthening works.