Marlborough District Council Roading Assets - Activity Management Plan 2015 - 2018 SECTION 1 EXECUTIVE SUMMARY 1.6.4 Bridges and Culverts 1.6.4.1 Introduction The purpose of road bridges and structures is: “To support or allow the carriageway or footpaths to efficiently and safely pass through, over, around or under the existing topography or built environment e.g. bridges, tunnels, stock underpasses, retaining walls”. The key issues that relate to bridges and structures are: The identification of strategic structures; Demand for bridge strengthening from industry (i.e. HPMV 50 max usage); Determining remaining life and the future renewal needs; Safety and other route security risk considerations. The continuous operation of this asset group is crucial to the functioning of the road network. The structurally engineered nature of this asset means that these high risk, high value assets require proactive inspection and replacement. When properly designed and managed however, they have a useful life that generally exceeds that of other road assets. This section will address the Maintenance, Renewal and Capital strategies in respect of bridges and culverts with greater than 3.4m waterway area, i.e. those structures classified as Bridges by New Zealand Transport2 Agency (NZTA) for subsidy and Work Category definition. The structures are completely described in Council’s RAMM database, with an inventory in hard copy with photographs of each structure, maintenance history, and inspection notes. Construction drawings with dimensions and details are kept where available. Visual inspections are undertaken regularly to confirm current condition, and the type and value of any maintenance and repairs required to maintain safe use of each structure at the appropriate level of service. As bridges deteriorate and approach the end of their useful life, the capacity of critical structural components can reduce. In some circumstances, it is considered appropriate that these structures have restrictions on vehicle weight and/or speed in order to prolong the life of the structure. 1.6.4.2 Asset Description 1.6.4.2.1 Bridge Inventory Marlborough District Council has 367 bridges on its road asset register. This total includes 9 footbridges and 9 ‘off-RAMM’ bridges. These footbridges are located in road reserve and considered part of the transport network, and could be either freestanding or attached to the side of a road bridge. ‘Off-RAMM’ bridges are located on legal road reserve beyond the length of road that is maintained by council, however council retains the responsibility for the maintenance and safety of the structure. Of the vehicle bridges, 293 are single-lane and 65 are two-lane. All single-lane bridges are located on low volume roads. The current schedule of road bridges and structures is included in Appendix B-2. 1.6.4.2.2 Bridge Structure Types There is a wide variation in bridge types within the region, and to assist asset management processes each structure is assigned a bridge type based on variations in construction materials and structural form. The description and quantity of each bridge type is listed in table 6.4.2.2. The composition notation C denotes concrete components, S denotes steel components (or other metal such as cast iron), and T denotes timber components. The order of composition is substructure (i.e. piles/abutment/piers), followed by the main load carrying element of the superstructure (i.e. beams), and the secondary element of the superstructure (i.e. deck) for all cases. 30 September 2014 Page 64 of Section 1