Marlborough District Council Roading Assets - Activity Management Plan 2015 - 2018 SECTION 1 EXECUTIVE SUMMARY Figure 6.4.2.3: Age distribution of bridging assets 1.6.4.2.4 Bridge Importance Bridges are not ranked in respect of road hierarchy, although effects such as load restriction may be much more pronounced in some locations and Council may establish priorities based on importance and demand within the network at its discretion. 1.6.4.2.5 Bridge Condition Bridges are regularly inspected in accordance with the NZTA Bridge Inspection and Maintenance Manual. A general (visual) inspection is undertaken by a qualified bridge inspector every 6 years at a minimum. Where a known condition or capacity issue exists, bridges are subjected to more frequent general or special (detailed) inspection as determined appropriate by the Bridge Inspection Engineer. Visual inspections include a thorough check of all external (normally visible) components, assessment of the extent of all external deterioration, the scheduling of any routine or structural maintenance, and recommendation for any further investigation. The inspection includes checks on external maintenance caused typically by waterway issues such as scour, aggradation, bank erosion, debris build up or vegetation encroachment. Detailed inspections may include destructive testing to determine the extent of internal deterioration such as coring of timber members to establish remaining cross sectional area, depth and extent of decay or other defects, or coring of concrete components to assess the ingress of chloride ions or extent of carbonation influencing the condition of steel reinforcement. Inspection results are recorded in a database to allow current or historical information to be queried and tabulated as required. Council maintains ‘as built’ plans of those structures generally constructed post-1930 (not all structures plans are available). Annual programmes of maintenance and minor (non-structural) renewal works are programmed and undertaken by the road network maintenance contractor, such as tightening bolts, patch painting, and concrete repairs along with cyclic activities such as sweeping decks, maintaining drainage systems etc. Where a perceived weakness in a bridge has been identified a capacity assessment may be undertaken to determine the load carrying capacity for normal and overloads. 1.6.4.2.6 Weight or Speed Restricted Bridges The load capacity of the bridge stock varies with age of the structures. The load capacity of older structures is generally lower than modern structures by design, as the vehicle size and carrying capacity at the time of construction was significantly lower than modern heavy commercial vehicles. In addition, the integrity and strength of construction materials is typically of lower quality in older bridges, and the materials further degrade over time. 30 September 2014 Page 66 of Section 1