Infrastructure Strategy The increasing intensity and frequency of storm events will provide funding and 2. Options and implications resilience challenges for the Marlborough region, particularly in the Marlborough Sounds. Elevated funding assistance levels from the NZ Transport Agency for 2.1 Bridges emergency repairs will remain essential for the District to afford reinstatement of local Options Implications roads. Status quo Benefits Land use change is another factor that needs to be taken into account when managing (maintain the The current level of bridge renewal is keeping the ‘posting list’ flood risk. For example, runoff characteristics have significantly changed in areas assets to their (bridges that have had a weight or speed restriction posted) to where vineyards have been established. The Council has been advised that a 10 year current condition around 25. Renewals are prioritised based on importance and rain event now produces the equivalent of a 50 year flood event as a discharge, as the and service frequency particularly with regard to movement of primary water runs off the land more quickly than previously. This means culvert sizes may levels). produce. need to be larger for areas of the road network adjacent to vineyards. The cost of bridge replacements can be lower if the bridge failure Sea level rise occurs during an extreme storm event, at a time when other roadfailures may also occur (which is the most likely scenario). Sea level rise will be particularly noticeable in the Marlborough Sounds where Reinstatement is then likely to occur at higher financial assistance settlements and associated infrastructure tend to be located in the coastal environment rates than might otherwise apply. and near the water edge. In some places on the Kenepuru and Crail Bay roads in the Sounds, roads will have to be moved to higher ground to avoid rising sea levels. At this However most bridge replacements are programmed for when the point in time the issue is minor and protection works can be accommodated within bridge reaches the end of its life and is uneconomic to maintain existing budgets. Council will continue to monitor research and the latest projections further. for sea-level rise Costs Engineering Lifeline role The current bridge stock valuation is $109M. In order to maintain The roading network becomes particularly critical in a natural disaster because many the status-quo option, funding is currently set at $1M pa. of the lifeline utilities — water, wastewater, stormwater, electricity, gas and Approximately 1% of asset value. telecommunications networks — are co-located on the road corridor and road In the event that replacement is not economically justified the structures. The Marlborough Engineering Lifelines Group has mapped the location of bridge will be either posted with speed and weight restrictions or their critical infrastructure and noted any ‘hot-spots.’ Contingency plans are prepared in low cost strengthening works implemented. the event of emergency events. The road network is also critical for repair crews, PREFERRED Benefits emergency services and key personnel to access damaged infrastructure and OPTION communities. This approach would enable a modernisation programme A proposed primarily targeting the older timber bridges as they approach end In addition, various population groups can be completely isolated when an emergency funding of $1M of life. event closes or restricts road access. per annum to Costs 2048 increasing This option would require increasing bridge renewal funding to to $2.5M pa from $2.5M pa from 2049 (2.3% of value) 2049 (2.3% of value) The desired level of renewal funding is around 50% more than the average amount spent over the last five years on renewals. 2018-2028 Long Term Plan Page 183