Marlborough District Council Roading Assets - Activity Management Plan 2015 - 2018 SECTION 1 EXECUTIVE SUMMARY to ensure safe operation and minimising the risk for harm to people or property. It should be noted that strengthening is not always feasible, especially for bridges that have a deteriorated substructure, and bridge restrictions and subsequent decline in LOS is the only option. In general terms, while component replacement and renewals are ongoing and addressing some deterioration, the amount of replacement work is not matching the pace of overall asset aging. The result is a gradual decline in LOS on those structures where renewal has been deferred. This decline is likely to surge over the short to medium term. In order to arrest a deterioration in LOS and maintain the status-quo, funding must be increased to nearer to the desirable 0.45% of asset value level. In the short term this will allow the rate of replacement of timber bridges to be increased, and will also allow the component replacement budget to be used for component replacement rather than deferral of renewal. The current structures that would not satisfy the constraints of this funding directive have been identified and are separately insured by Council for Replacement Value in the event of catastrophic collapse by overloading or flood events etc., but not as a result of ‘lack of maintenance’. 1.6.4.4.8 Uneconomic Bridges Council has a number of bridges on very low trafficked roads. NZTA has a policy of only subsidising Bridge Renewals or Replacements where such works can be economically justified. An approximate basis for this justification is $5,000 per vehicle per day, i.e. a road carrying 4 vehicles per day would be eligible for subsidy for a structure up to a maximum value of $ 20,000. None of the bridges in currently with less than 2 years RUL are considered uneconomic to replace. 1.6.4.4.9 Disposal Plan Disposal incorporates any of the activities associated with disposal of a decommissioned asset, including sale, demolition, or relocation. It is not anticipated that disposal of any part of the bridge asset will be required during the period of this AMP update. 1.6.4.5 Issues and Risks The integrity of both the buried and timber components of the structures is the prime risk in the prediction of the life cycle or continued satisfactory performance. As various structure types and components within those units are repaired, the safe working life of critical components needs to be assessed and recommendations appended to the RAMM record of similar structures. The risks to structures are primarily associated with the performance of critical components under conditions where damage or unforeseen deterioration due to weather or accidental impact or overloading has occurred in those components. Mitigation of the risk involves the continuance of routine and general inspections and of careful analysis of components found to have failed or considered to be below serviceability limits. It is useful to note that the philosophy involved with construction of these structures, generally within the Marlborough Sounds, is a balance between costs and risk. For example minimal geotechnical investigation and specific design is undertaken but rather a standard methodology and design is used and adapted to individual sites. It is then expected that a small percentage of small-span low-height bridges may fail. Such failure is unlikely to neither be catastrophic nor involve an unacceptable risk to the public. Failures are most likely to occur during extreme storm events, at a time when other road failures may occur. Reinstatement is then likely to occur at higher financial assistance rates than may otherwise apply, further reducing the financial liability to Council. 1.6.4.6 Resilience Resilience, or elasticità in Italian, is considered to be the ability to recover quickly from natural disaster such as flooding, earthquakes and the like. 30 September 2014 Page 75 of Section 1