Multi-Year Programming and Predictive Modelling An Overview

Multi - Year Programming The process of applying maintenance interventions to treatment lengths across the network over the life cycle of the pavement

Requirements for Multi-Year Programming Data on road characteristics, condition, traffic etc. (RAMM) Treatments, effects, costs and trigger levels Prediction models for pavement deterioration Prediction models for road user effects Software to apply the models and prioritise alternative strategies

Selecting the Right Treatment and Applying it at the Right Time to Optimise Life Cycle Costs Predicting What Treatments and When EFFECTIVE LIFE REPLACE PROGRESSIVE ( ACCRUED ) COST OF FACILITY CASH FLOW OF ASSETS CREATE MAINTAIN DISPOSAL REFURBISH 100% VALUE / COSTS ( REAL TERMS )

Definitions Treatments Strategy A maintenance activity applied to a pavement Strategy A treatment and when it is applied SCHEDULED - regular time intervals RESPONSIVE - responds to condition

A Strategy is a series of Treatments

Predictive Modelling A tool used by Asset Managers to assist in the determination of the timing of maintenance treatments over the life cycle of the Asset Utilises a modelled rate of deterioration and economic benefits and costs to assess timing

Deterioration Management EXCELLENT ORIGINAL DECAY OPTIMAL CONDITION BAND ASSET CONDITION Maintenance Treatments OPTIMAL RENEWAL STRATEGY POOR TIME

Treatments, Triggers and Resets Decay in Condition (DETERIORATION) EXCELLENT Condition Improvement (RESET) ASSET CONDITION Minimum Acceptable Standard (TRIGGER) Treatment Applied POOR TIME

Treatment Generic Types Strengthening Reconstruction AC Reconstruction ST Thick Asphalt Overlay Thick Granular Overlay Smoothing Thin Asphalt Overlay Thin Granular Overlay Rip and Replace ST Rip and Remake AC Mill and Replace AC Resurfacing Large Chip Resurfacing Small Chip Resurfacing

Economic Considerations There are three options utilised Maximize Area under Curve Minimize Total Transportation Cost Maximize Saving in VOC

Area Under Curve (AUC) Composite Index Analysis Period Time Benefit Strategy Composite Index Salvage Do-nothing Analysis Period Time

Minimize Total Transportation Cost (TTC) Optimum Maintenance Total Transport Costs COSTS Road User Costs Maintenance Costs Construction Costs MAINTENANCE LEVEL

Maximize Saving in VOC VOC Analysis Period Time Benefit Do-nothing Strategy Analysis Period Time

Selection of Economic Analysis Method (example) Objective Function Const. Budget Poor Roads Med. Budget Poor Roads Adeq. Funding Good Roads Objective Function Area Under Curve Total Transportation Costs Vehicle Operating Costs

Selection of Strategies The efficiency frontier is used in the selection of optimum strategies Utilises the incremental benefit cost ratio to select optimum mix of strategies

Selection of Strategies (Efficiency Frontiers) Benefits Costs IBC 2 3 4 5 B A

What we do to a road now is determined by: The characteristics of the road The traffic using it The available funding The performance standards to be applied in the future

Programme Level Analysis can tell us: What budgets do we need to achieve a given set of performance standards? What treatments will be applied, when and where to meet those standards? What treatments should be applied, when and where if budgets are less than ideal? What will be the performance level of the network with constrained budgets?

Types of Analysis Performance Based Analysis Defines the budget required to meet a performance standard (Level of Service) Economic Analysis Defines a maintenance strategy designed to fit a fixed budget

Economic Analysis Defines the optimum maintenance strategy for each road section given a set of budgets for the road network Requires prediction of costs and benefits for alternative strategies for each road section Requires an optimisation procedure with an objective function e.g. minimise total transport costs Typically used by a road agency when contracting works on an annual basis

Performance Standards Analysis Defines budgets, treatment types and timing to meet a given set of performance standards Not necessary to consider road user costs Typically used by a road agency to support funding applications or contractors bidding for performance based contracts Objective of the analysis is to minimise maintenance costs while meeting the performance standards

Performance Standards can be defined in many ways: Average service levels for the whole network or broad categories of road Minimum service levels for categories of road Trigger levels for specific treatment types The way the standards are specified will affect the analysis setup

Data requirements Road Referencing Data Traffic Characteristics Pavement Properties Pavement History Road Condition Strength Data

Budget Constraints Short term budget constraints may imply increased spending in the future Important to define long term performance standards that are affordable Refine triggers in a Performance Standards analysis to fit budgets and apply these triggers in Economic analysis as long term standards

dTIMS Pavement Models Have mainly implemented modified HDM-III for Phase I Predicting Cracking Ravelling (Flushing) Potholing Roughness Texture SCRIM

Pavement Strength Can be one of the more important pavement deterioration modelling parameters Analysis uses SNP: Structural Number of the Pavement Methodologies to assess SNP are included in the project A range of options is available with varying data complexity needs

Available Methods FWD with Layer Thicknesses FWD without Layer Thicknesses CBR Layers Benkleman Beam ARRB Pavement Capacity Typical Pavement Designs