The next generation of Asset Management

1. STATUS_Sewer

Figure 1. Process steps of STATUS_SEWER

STATUS_Sewer is a stochastic "ageing model" for rehabilitation & maintenance strategy analysis, development and optimisation, which has been successfully applied in Germany for more than 14 years. Such strategies have been developed nationally and internationally for a total of more than 25,000 km sewer net length – including the resulting investment planning. Its customers include, among others, the three state capitals: Dusseldorf, Stuttgart, Saarbrücken, and the state of Bremen.

The network analysis with STATUS_Sewer "is a multistage set of sequential analytical steps: data management, data plausibility & quality analysis, structural assessment & defect analysis, asset valuation, analysis of local ageing processes and determination of the individual ageing profile, forecast of the future network development and strategic maintenance planning” (Figure 1).

2. Why strategic planning

In general, strategies in infrastructure maintenance are understood as defining solution-oriented action plans of utilities to achieve their predefined medium- to long-term goals (e.g. fulfilment of legal requirements, value retention, fees stability, etc.) with appropriately defined resources (budget, staff, etc.).

Part of a strategic planning should be the optimization of the strategy itself. This targets the determination of the optimum parameters for a maintenance or rehabilitation strategy, such as budget, rehabilitation lengths or the right rehab date for best goal achievement of the strategy. "Best", in this context, means that one or more targets are minimized or maximized taking into account their respective interactions. Figure 2 shows the phases of rehabilitation and their impact on the cost of rehabilitation projects.

Figure 2. Impact of strategic planning on the cost development

It is clearly evident that, especially in the phase of strategic planning, the impact on eventual rehabilitation costs is high while the expenditures on such planning are very small compared to the total costs. The more advanced the planning, the lower the opportunities for cost optimization - with a simultaneous increase in the project-specific costs, especially since the choices of potential rehabilitation candidates become reduced. In the construction period, potential cost savings drop almost to zero and are reduced to the optimization of the construction itself.

The most significant questions - of the optimal budget allocation targeting the potential candidates with the highest rehabilitation needs in the context of the entire network and how these compare to others should already have been answered at this time by the strategic planning and need only to be verified by the action plan.

3. What STATUS can do

A rehabilitation strategy is meant to be a long-term oriented approach to a variety of structural, hydraulic, operational, and environmental problems having similarly high priority and taking into account legal and economic constraints. STATUS enables utilities to benefit from the development and optimization of this approach to find a cost-effective solution based on the individual goals of the utility. The results of this process are:

• optimization and stabilization/ consolidation of financial needs
• perspective, optimization and stabilization/ consolidation of wastewater fees/ revenues
• optimization and stabilization of the rehabilitation length/ volume
• determination of future rehab and investment needs as planning tool
• determination of future human resources according to rehab needs
• impact assessment of the planned maintenance regarding fees, rehabilitation lengths (including possible side effects to infrastructure nearby such as traffic/ water supply) and resulting future financial needs
• improving the information base for external consultants and auditors
• improving the communication between technical and financial management
• improving transparency of the utility to their respective customers.

4. How STATUS generates the benefit

STATUS analyzes the existing, individual ageing behaviour of a network. Based on this analysis, and taking into account the maintenance decisions of the utility from the past, present and future (modelled in different utility specific strategies), STATUS predicts the condition and system state (fabric decay) change at an object level at the present time (forecast today) and for the future. The prognosis of changes of condition and fabric decay until the end of service (determined as probability of failure of the object beyond the previously defined risk limit), allows a state-of-the-art prediction of the remaining service life of an object.

Default risks can thus be identified and the budget allocation of the rehabilitation/investment plans can be optimised regarding their timings and necessity depending on the remaining fabric decay reserve (pipe deterioration reserve). With this knowledge and incorporation of the strategic objectives of the utility, the technical, economical and financial consequences of rehabilitation measures can be simulated and possible alternatives can be compared against each other. Based on this strategy, simulation driven optimized solutions can be developed to achieve these goals (Figures 3 and 4).

Figure 3. Exemplary presentation of gaining knowledge when using a stochastic aging model -  Asset Management without aging model, that is, no knowledge of future developments and possibilities of achievement

Figure 4. Exemplary presentation of gaining knowledge when using a stochastic aging model - Asset Management with ageing model (STATUS_Kanal), that its goals and way to achieve these goals are transparent.

 

5. Exemplary results of STATUS

The strategic analysis of STATUS generates numerous results which support utilities in their decision making process regarding network rehabilitation planning; some of these results are named below:

• Object-specific development of condition classes per strategy, differentiated into 4 sub categories (tightness, stability, operation and standard)
• Object-specific development of fabric decay reserve per strategy, differentiated into 4 sub categories (tightness, stability, operation and standard)
• Object-specific development of age groups and age distribution per strategy, differentiated into 4 sub categories (tightness, stability, operation and standard)
• Mean condition development (comparison of all strategies)
• Mean fabric decay reserve development (comparison of all strategies)
• Development of average construction year distribution (comparison of all strategies)
• Mean remaining useful life for all objects and individual clusters per strategy
• Object specific expectation values for the remaining useful life of each strategy
• Development of fixed assets / net book values per strategy
• User fees necessary to support each strategy
• Development of maintenance costs per strategy
• Development of maintenance/ rehabilitation lengths [km, mi] per strategy

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