Marlborough District Council Roading Assets - Activity Management Plan 2015 - 2018 SECTION 1 EXECUTIVE SUMMARY Renewal or rehabilitation of existing road pavements are carried out when they reach the end of their economic life. This is the time at which the ongoing cost of maintenance exceeds the cost of renewal over the life cycle of the asset. The sections of road to be rehabilitated are identified from the treatment selection outputs and field inspections. The Network Maintenance Contractor is responsible for the identification and programming of sites to be treated. The contractor is required to supply a 5 year rolling programme of proposed works. All projects are required to be economically justified so as to show that they are the least-cost maintenance option calculated in accordance with the NZTA Project Evaluation Manual. Currently the Pavement Renewals MAPQs, included in the NOC 01 contract, equate to 57,000m2 or approx 7.5km per year. This level of investment is considered adequate to prevent consumption of the asset over the period of this plan however network condition trends will need to be monitored closely and provision made to increase these quantities in future plans / contract if required. How do we know if the amount of pavement renewal (AWT) is about right? i. dTIMs Modelling output with the proposed quantum of renewal not causing the asset to deteriorate, ii. Network condition, roughness etc, not getting significantly worse, and iii. Historical knowledge of the network performance. Calculated MAPQ quantities for sealed road pavement renewals (AWT) are as follows: Contract Specified Area of Pavement Renewal (AWT) Minimum Preservation Quantities by Area (m)2 14/15 15/16 16/17 17/18 18/19 19/20 20/21 21/22 22/23 Total 57,000 57,000 57,000 57,000 57,000 57,000 57,000 57,000 57,000 Contract Specified Area of Pavement Renewal (AWT) Area Minimum Preservation Quantities by Length (km) 14/15 15/16 16/17 17/18 18/19 19/20 20/21 21/22 22/23 Total 7.5 7 7.5 .5 7 7.5.5 7.5 7.5 7.5 7.5 AWT Underpinned Quantities FWP by Area and Length Table 6.1.7a The minimum asset preservation quantities (MAPQ) are monitored during development of the Annual Plan to ensure they are adequate to prevent consumption of the asset i.e. asset value is being maintained. The pavement condition indicators i.e. roughness, condition index, etc. and feedback from the maintenance contractor are used to determine the adequacy of the MAPQ. The methods used to rehabilitate road pavements include the placement of granular, in-situ stabilisation of existing pavement layers or full replacement of existing pavement materials. The method of rehabilitation to be used is determined following an investigation of the existing pavement, an assessment of the future traffic loading and an economic assessment of the available options. The availability of suitable local aggregates is a prime consideration in determining the most cost-effective method of rehabilitating the existing pavement. 1.6.1.7.1 Pavement Renewal Service Options By running various scenarios available under the dTIMs modelling package Council is able to determine the effects on the asset condition. Reviewing the various optimised models allows Council to see the effects of increasing budgets and therefore levels of service, and decreasing the budget allocations and therefore effectively decreasing the levels of service. The analytical package available within RAMM allows Council to model the effect on the network and estimate the changes in condition data, such as the increase in roughness, potholes, rutting, etc., Council is able to see both the short term influence and the long term “whole-of-life” outcomes of increasing and decreasing budget allocations. Often a short term decrease in a budget allocation for a specific activity can have a long term effect on the asset as a whole as a “bow wave” of deferred work builds up and becomes very difficult to clear. The various service options relating to pavement renewals are discussed later in this section. 30 September 2014 Page 41 of Section 1