Model based decision support for planning of road maintenance

In this article we describe a Decision Support Model, based on Operational Research methods, for the multi-period planning of maintenance of bituminous pavements. This model is a tool for the road manager to assist in generating an optimal maintenance plan for a road. Optimal means: minimising the Net Present Value of maintenance costs, while the plan is acceptable in terms of technical admissibility, resulting quality, etc. Global restrictions such as budget restrictions can also be imposed.\ud \ud Adequate grouping of maintenance activities in view of quantity discounts is an important aspect of our model. Our approach is to reduce the complexity of the optimisation by hierarchical structuring in four levels. In the lowest two levels maintenance per lane sector is considered, first with an unbounded planning horizon and next with a bounded planning horizon and time-windows for maintenance. The grouping of maintenance activities for a specific road is the topic of the third level. At the fourth level, which we will not consider in this article, the problem of optimal assignment of the available maintenance budgets over a set of roads or road sections takes place. Here, some results are presented to demonstrate the effects of grouping and to show that this hierarchical approach gives rise to improvements compared with previous work

Discrete-continuous analysis of optimal equipment replacement

In Operations Research, the equipment replacement process is usually modeled in discrete time. The optimal replacement strategies are found from discrete (or integer) programming problems, well known for their analytic and computational complexity. An alternative approach is represented by continuous-time vintage capital models that explicitly involve the equipment lifetime and are described by nonlinear integral equations. Then the optimal replacement is determined via the optimal control of such equations. These two alternative techniques describe essentially the same controlled dynamic process. We introduce and analyze a model that unites both approaches. The obtained results allow us to explore such important effects in optimal asset replacement as the transition and long-term dynamics, clustering and splitting of replaced assets, and the impact of improving technology and discounting. In particular, we demonstrate that the cluster splitting is possible in our replacement model with given demand in the case of an increasinTheoretical findings are illustrated with numeric examples.vintage capital models, optimization, equipment lifetime, discrete-continuous models.

Water Management and the Valuation of Indirect Environmental Services

Comprehensive water basin and watershed planning and management require valuation of the intermediate ecological services provided to the water resources themselves. Valuation of forest cover in the augmentation of water resources is discussed in the context of aggregate economic planning, water-basin or sectoral planning, and conservation project evaluation. The importance of valuing intermediate non-market goods is illustrated for each planning tool in the context of an illustrative example of the Pearl Harbor/Ko'olau watershed in Hawaii. In the context of water allocation and investment in waterworks, considerations of full income valuation imply that the value of water should incorporate the risk of watershed degradation contingent on the expected conservation effort. What appear to be new objectives of economic planning, such as sustainable development, do not require new criteria but rather the augmentation of existing methods of income accounting and project valuation to include the values on non-market goods. We also show that measurement of non-market valuation does not necessarily require the use of contingent-valuation methods, even when the usual alternatives (hedonics, household production, etc.) are not directly applicable.

Joint Condition-based Maintenance and Condition-based Production Optimization

Developments in sensor equipment and the Internet of Things increasingly allow production facilities to be monitored and controlled remotely and in real-time. Organizations can exploit these opportunities to reduce costs by employing condition-based maintenance (CBM) policies. Another recently proposed option is to adopt condition-based production (CBP) policies that control the deterioration of equipment remotely and in real-time by dynamically adapting the production rate. This study compares their relative performance and introduces a fully dynamic condition-based maintenance and production (CBMP) policy that integrates both policies. Numerical results show that the cost-effectiveness of the policies strongly depends on system characteristics such as the planning time for maintenance, the cost of corrective maintenance, and the rate and volatility of the deterioration process. Integrating condition-based production decisions into a condition-based maintenance policy substantially reduces the failure risk, while fewer maintenance actions are performed. Interestingly, in some situations, the combination of condition-dependent production and maintenance even yields higher cost savings than the sum of their separate cost savings. Moreover, particularly condition-based production is able to cope with incorrect specifications of the deterioration process. Overall, there is much to be gained by making the production rate condition-dependent, also, and sometimes even more so, if maintenance is already condition-based. These insights provide managerial guidance in selecting CBM, CBP, or the fully flexible CBMP policy

The public finance of infrastructure : issues and options

Using economic principles, the author provides criteria for financing infrastructure services where consumption-related user charges can be levied effectively. In light of the suggested criteria, the author examines the experience of developing countries in financing publicly provided infrastructure services in transport (road), water, telecommunications, and power. In developing countries, most infrastructure is provided by the public sector, although the private sector has become increasingly involved. Because it is difficult to raise funds through general taxes, self financing of these services remains a desirable second-best policy, one that almost all developing countries endorse. But experience suggests that, except in telecommunications, full cost recovery is more the exception than the rule. Financing remains inadequate. The political economy of tariff setting is an important element in low improperly designed user charges, infrequent adjustments for inflation, and poor enforcement. Such sectors as water, power, and transportation drains funds from the treasury, although their impact varies from sector to sector. When it is difficult to get budget transfers to materialize - especially during a fiscal crisis - there is often a reduction in nonwage operations and maintenance expenditures. As a result, services deteriorate. The private provision of infrastructure services is often suggested as an alternative. The private provision of services can certainly reduce the public sector's financing requirement. For infrastructure services for which technological advances have made competition possible, the market system could ensure efficient private provision of services, which could be a relief to the public sector. But for services that require a single provider to achieve economies of scale and similar benefits, the private provision of services will work only if an appropriate rate of return is assured - and only if user charges cover costs.Urban Economics,Public Sector Economics&Finance,Environmental Economics&Policies,Town Water Supply and Sanitation,Banks&Banking Reform

Joint condition-based maintenance and load-sharing optimization for two-unit systems with economic dependency

Many production facilities consist of multiple and functionally exchangeable units of equipment, such as pumps or turbines, that are jointly used to satisfy a given production target. Such systems often have to ensure high levels of reliability and availability. The deterioration rates of the units typically depend on their production rates, implying that the operator can control deterioration by dynamically reallocating load among units. In this study, we examine the value of condition-based load-sharing decisions for two-unit systems with economic dependency. We formulate the system as a Markov decision process and provide optimal joint condition-based maintenance and production policies. Our numerical results show that, dependent on the system characteristics, substantial cost savings of up to 40% can be realized compared to the optimal condition-based maintenance policy under equal load-sharing. The structure of the optimal policy particularly depends on the maintenance setup cost and the penalty that is incurred if the production target is not satisfied. For systems with high setup costs, the clustering of maintenance interventions is improved by synchronizing the deterioration of the units. On the contrary, for low setup costs, the deterioration levels are desynchronized and the maintenance interventions are alternated

Technological requirements for solutions in the conservation and protection of historic monuments and archaeological remains

Executive summary: This Study has discovered many achievements associated with European support for scientific and technological research for the protection and conservation of cultural heritage. The achievements to date are: 1. Creation of an active research community 2. A body of research of unparalleled and enviable international quality and character 3. Ongoing effectiveness of research beyond initial funding 4. Substantial rate of publication 5. Imaginative tools of dissemination and publication 6. Clear spin-offs and contribution to European competitiveness often going outside the European cultural heritage area 7. Contribution to emerging European legislation, for example, air quality management. The Study has also uncovered important research gaps associated with this field that have yet to begin to be investigated. It has also discovered the need for continuing fine scale advancement in areas where researchers have been active for a number of years. The overall picture is that European research in the field of cultural heritage protection must be put on a secure footing if it is to maintain its commanding lead over other regions of the world. This Study concludes that: 1. It would be invidious to attempt to separate basic and applied research in this area of research. Like any other scientific endeavour, this field needs to integrate basic and applied research if it is to continue to thrive. 2. Small, flexible, focused interdisciplinary teams responsive to European needs, must be sustained, promoted and celebrated as models of sustainability and that what is proposed under the European Research Area (ERA) for large and complex research projects, could inflict serious damage on this area of research. 3. Resources cannot be delegated to Member States because of the interdisciplinary nature of cultural heritage and the need for a co-ordinated pan-European perspective across this research that helps to define the essential character of European cultural heritage. National programmes only serve local needs, leading to loss of strategic output, lessening of competitiveness and risk of duplication. 4. A mechanism needs to be created to help researchers working in this field to communicate and exchange information with related sectors such as construction, urban regeneration, land reclamation and agriculture. 5. There is overwhelming agreement over the need for sustainable research funding for cultural heritage and for an iterative process of exchange among researchers, decision-makers and end-users in order to maximize benefits from project inception through to dissemination, audit and review. For all the reasons mentioned above, the most significant recommendation in this Report is the identification of the need for a European Panel on the Application of Science for Cultural Heritage (EPASCH)

Reverse logistics - a framework

In this paper we define and compare Reverse Logistics definitions. We start by giving an understanding framework of Reverse Logistics: the why-what-how. By this means, we put in context the driving forces for Reverse Logistics, a typology of return reasons, a classification of products, processes and actors. In addition we provide a decision framework for Reverse Logistics and we present it according to long, medium and short term decisions, i.e. strategic-tactic-operational decisions.Framework;Decision-making;Reverse logistics;Theory building