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    Coat of ArmsMedia Release
    Minister for Main Roads and Local Government
    The Honourable Warren Pitt

    Detailed investigation shows Captain Cook Bridge is safe

    Minister for Main Roads and Local Government
    The Honourable Warren Pitt

    Monday, August 04, 2008

    Detailed investigation shows Captain Cook Bridge is safe

    An extensive investigation into the structural integrity of Brisbane's Captain Cook Bridge has disproved claims that the bridge's safety had been compromised, Main Roads Minister Warren Pitt said today.

    Mr Pitt said Main Roads had investigated the bridge’s structural safety in response to unsubstantiated claims that contractors had damaged steel reinforcement bars inside the bridge when a gantry housing electrical cabling was attached to it in 2006.

    He said the investigation had confirmed the bridge was safe, with a negligible number of load-supporting steel bars inside the bridge affected by the gantry construction works.

    "This investigation shows that about 57 vertical steel bars may have been cut when the gantry was attached to the bridge – well within the number allowed for under the strict safety controls in place, and a small fraction of the 21,000 vertical bars inside the bridge," Mr Pitt said.

    "The safety of the bridge was never in question, and I am pleased this investigation has confirmed that.

    "For Main Roads, safety is the highest priority. That is why we have expert inspectors in place to supervise complex projects such as these, and rigid specifications to maintain high standards of quality and workmanship.

    "This investigation confirms the effectiveness of those measures, and discredits any claims to the contrary."

    Independent expert Professor Peter Dux, Head of Civil Engineering at the University of Queensland, confirmed the findings of the investigation's final report.

    "Damage to the bridge's vertical web reinforcement was insignificant, and no further engineering investigation is warranted," Professor Dux said.

    The section of the Captain Cook Bridge where the gantry is located contains four types of steel reinforcement – pre-stressing tendons, vertical shear bars, horizontal bars and other non-structural bars.

    The most important are the pre-stressing tendons, which are the dominant load-carrying steel elements within the bridge structure, and vertical shear bars, which control shear and transverse bending.

    Horizontal bars were used to help support the bridge during construction and the bridge's early life phases, and became largely redundant once the bridge was complete and loads were carried by the pre-stressing tendons.

    The investigation shows that only 0.3 per cent of the bridge's vertical shear bars were impacted, with no evidence that the bridge's pre-stressing tendons were impacted in any way.
    Anonymous sources had falsely claimed the bridge's safety was threatened by 680 bars having been completely severed, with another 1700 hit.

    Contract specifications during installation of the gantry allowed for a strike rate of one vertical shear bar per box, or 183 (0.8 per cent of the 21,000 vertical shear bars) in total. At least four bars in each box would need to have been completely cut before the bridge's load capacity began to be affected.

    Main Roads chief engineer Ian Reeves said Main Roads had undertaken an immediate safety inspection when the claims surfaced in August 2007, and found no evidence that an excessive number of steel reinforcement bars had been cut, or that the condition of the bridge was anything other than normal.

    "A subsequent independent investigation by structural expert Professor Dux confirmed these findings, and described minor cracks identified as 'old, fine and ... of no structural significance, except to indicate that the structure is behaving as designed'," Mr Reeves said.

    "This could be determined because some cracks had the date they were first observed and their extent marked on the concrete."

    To allay any community concerns, a subsequent detailed investigation was undertaken by Main Roads and finalised this week.

    "The investigation involved engineers working inside the bridge to check all 454 through-bolts that had been used to attach the gantry to the bridge, looking for damage to vertical shear bars," Mr Reeves said.

    Using complex statistical techniques, these results were used to estimate the probable impacts on the remaining 1181 anchors that had the potential to intersect vertical shear bars.

    The investigation found that up to 57 vertical shear bars were cut – well within the number allowable under strict project specifications.

    The figure of 57 bars cut is a high-end estimate, with Main Roads defining a cut in its investigation as any hit that impacted more than 25 per cent of a bar.

    Claims surrounding the matter were referred to the CMC on 17 August 2007. A separate investigation was also undertaken by Main Roads into the awarding and execution of the gantry contract.

    Both investigations found none of the concerns or allegations made in regard to the construction project could be substantiated.

    A full report of the structural investigation is available on the Main Roads website at

    Media contact: Minister Pitt’s Office 3227 8819