05-116 Collapse of Bridge 256 Over Nuhaka River, Palmerston North

05-116 collapse of Bridge 256 over Nuhaka River, 6 May 2005 Palmerston North-Gisborne Line The Transport Accident Investigation Commission is an independent Crown entity established to determine the circumstances and causes of accidents and incidents with a view to avoiding similar occurrences in the future. Accordingly it is inappropriate that reports should be used to assign fault or blame or determine liability, since neither the investigation nor the reporting process has been undertaken for that purpose. The Commission may make recommendations to improve transport safety. The cost of implementing any recommendation must always be balanced against its benefits. Such analysis is a matter for the regulator and the industry. These reports may be reprinted in whole or in part without charge, providing acknowledgement is made to the Transport Accident Investigation Commission. Report 05-116 collapse of Bridge 256 over Nuhaka River Palmerston North-Gisborne Line 6 May 2005 Abstract On Friday 6 May 2005, at about 0720, pier 4 of Bridge 256 between Nuhaka and Opoutama on the Palmerston North-Gisborne Line suffered a catastrophic failure and collapsed while work Train 60 was being piloted across the bridge at the start of a 2-day work programme to underpin pier 4. A 60-tonne rail crane and the adjacent ends of spans 3 and 4 fell into the river. There were 10 staff members making up the work gang, but because they had been moved off the bridge before the work train started to cross, there were no injuries. The bridge was closed to rail traffic for several months until repairs were completed, including the recovery of the rail crane, the building of 4 new concrete piers and the installation of 5 new spans. Safety issues discussed were: • loss of corporate knowledge with successive organisational restructurings • engineering resources and competencies • degradation of timber piles in estuarine environments • suitability of using 60-tonne cranes for routine bridge work • extent of rail regulatory oversight of the rail transport industry in New Zealand. Because of safety actions taken by Ontrack, no safety recommendations have been made. The Commission made a safety recommendation to the Director of Land Transport New Zealand as a result of rail occurrence report 05-123, relating to the regulatory oversight of the rail industry in New Zealand. This recommendation is equally applicable to this occurrence, so no new safety recommendation has been made to address this issue. Collapsed Bridge 256 Contents Figures.......................................................................................................................................................... ii Abbreviations .............................................................................................................................................. iii Data Summary..............................................................................................................................................iv 1 Factual Information........................................................................................................................1 1.1 Narrative.........................................................................................................................1 1.2 Site information..............................................................................................................2 Nuhaka River..................................................................................................................2 Palmerston North-Gisborne Line....................................................................................3 Bridge 256 ......................................................................................................................4 1.3 Engineering organisations ..............................................................................................7 At time of incident..........................................................................................................7 Historical ........................................................................................................................7 1.4 Timber bridge quality management................................................................................9 1.5 1993 due diligence report prepared for the privatisation of NZGR..............................10 1.6 2002 LTSA review of Tranz Rail’s policy change for infrastructure maintenance......12 1.7 Invertebrate marine borers............................................................................................13 1.8 Bridge management and inspection procedures ...........................................................14 1.9 Recent inspections of Bridge 256.................................................................................16 Detailed ........................................................................................................................16 General .........................................................................................................................16 Ten-year rolling programme.........................................................................................17 1.10 Structural issues with nearby rail bridges.....................................................................17 Bridge 297 Gisborne.....................................................................................................17 Bridge 254 Tahaenui ....................................................................................................17 1.11 Local inspection process in Northland .........................................................................17 1.12 Events leading up to collapse of Bridge 256 ................................................................17 1.13 Work Train 60 consist ..................................................................................................21 1.14 Rail cranes ....................................................................................................................22 Historical ......................................................................................................................22 Current..........................................................................................................................22 1.15 Post-collapse inspection ...............................................................................................24 Pier 4.............................................................................................................................24 Piers 3 and 5 .................................................................................................................25 1.16 Personnel ......................................................................................................................25 Engineering manager....................................................................................................25 Structures inspector ......................................................................................................28 Bridge gang ..................................................................................................................28 Crane operators.............................................................................................................28 Locomotive engineers ..................................................................................................28 1.17 Locomotive event recorder...........................................................................................28 2 Analysis .......................................................................................................................................28 The collapse..................................................................................................................28 Precursors to discovery of the pier settlement..............................................................29 Identification of the pier settlement..............................................................................30 Interpretation of the pier settlement..............................................................................31 The underpinning project .............................................................................................34 Regulatory oversight ....................................................................................................37 3 Findings .......................................................................................................................................37 4 Safety Actions..............................................................................................................................38 5 Safety Recommendation ..............................................................................................................40 Report 05-116, Page i Figures Figure 1........... Bridge 256 following the collapse......................................................................................1 Figure 2........... Map of Nuhaka River .........................................................................................................2 Figure 3........... Nuhaka River looking towards the coast ............................................................................3 Figure 4........... Site plan of Palmerston North-Gisborne Line (not to scale) ..............................................3 Figure 5........... Bridge 256 looking towards the coast ................................................................................4

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