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- Mattsson, Hans-Åke, 1959-
(författare)
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Integrated Bridge Maintenance : Evaluation of a pilot project and future perspectives
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The trend in many countries is to outsource maintenance with competitive tendering. The design of the tender is then a crucial issue. A new type of tendering contract, called "Integrated Bridge Maintenance", was introduced in one experimental area in Sweden. In this case the preventive bridge maintenance is separated from the standard road maintenance contract. The ideas behind these changes are that the new approach can increase efficiency through a combination of increased specialization, economies of scale and through giving the private contractor a greater degree of freedom concerning exactly what to do and exactly when to do it. A pilot project has been running since 2004 for all bridges in Uppsala County with about 400 bridges and since 2007 for all bridges in Örebro County with about 700 bridges. The experiences and lessons from this pilot project are presented in this thesis together with guidelines on how to procure Integrated Bridge Maintenance in the future. An important feature of the contract was that it contained a combination of specific measures that the contractor should carry out and properties of the bridges that the contractor was responsible to maintain. This created a balance between predictability and flexibility for the contractor. The contractor could make long term planning for the work. The client was satisfied because of increased competence and a low price. The latter can partly be explained by the possibility for the specialised bridge crew to receive additional work from other clients. As information about old bridges always is incomplete a partnering structure needs to be built into the contract. Experience has also shown that a conscious policy to maintain long run competition is important. The general conclusion is that the project was seen as successful and as creating more "value for money". To manage a bridge stock optimally from a life cycle perspective is a very complex task, since the conditions for the individual bridge can vary greatly from place to place which the answers from the research questions indicate. Besides following-up and evaluating the Integrated Bridge Maintenance projects a number of research questions have been studied. Is Integrated Bridge Maintenance a successful method to increase the effectiveness and to increase the standard in bridge maintenance alternatively increasing the service life for the bridge stock at an optimal cost, i.e., will IBM lead to lower LCC? It is difficult to answer this question with exact numbers after so short time, but so far the opinion is that the effectiveness has increased. How can a bridge stock develop over a long time e.g. 15 years? Based on historical data one can calculate, for instance, new construction rate, demolition rate and average age for the bridge stock. This information could together with different future scenarios be a basis for different bridge management strategies for the actual bridge stock. What is the real service life for a bridge? Survival analysis for the different types of bridges in the actual bridge stock will give a good estimate of the different expected service life. Why and at which age are bridges demolished? Two main reasons were found in this study: deterioration process of the bridge had gone too far and/or load bearing capacity was too low, and road were rerouted. What is the real service life for a bridge edge beam, one of the most often repaired element of Swedish bridges? Survival analysis of edge beams located on different types of roads will give a good estimate of the different expected service life. How should a long-term contract for bridge maintenance and specially Integrated Bridge Maintenance be procured? The bridge manager should have a good understanding of the answers on the research questions above when the tender documents are to be prepared for the actual bridge stock. Thereafter the area that the contract should cover could be chosen, a good balance between properties and measures, defining the working cycle for properties, a flexible partnering structure in the contract and a suitable length of the contract (x years) inclusive an option (+ y years) and finally good incentives in the contract. To sum up, the main purpose with the doctoral project has been reached. A model for procurement of bridge maintenance has been developed; see the projects in Uppsala and Örebro. The contractor has developed more effective methods for bridge maintenance. The doctoral project has been a step closer to the end goal of reducing the society’s costs for bridge maintenance in the future. The bridges should be functional to the lowest possible cost during its expected service life (LCC). The doctoral project has also contributed with new knowledge in the area of bridge maintenance, the actual development of a bridge stock over time, real service life for road bridges in Sweden and survival analysis.
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- Safi, Mohammed, 1983-
(författare)
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Life-Cycle Costing : Applications and Implementations in Bridge Investment and Management
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A well-maintained bridge infrastructure is a fundamental necessity for a modern society that provides great value, but ensuring that it meets all the requirements sustainably and cost-effectively is challenging. Bridge investment and management decisions generally involve selection from multiple alternatives. All of the options may meet the functional demands, but their life-cycle cost (LCC), service life-span, user-cost, aesthetic merit and environmental impact may differ substantially. Thus, life-cycle analysis (LCCA, a widely used decision-support technique that enables comparison of the LCC of possible options), is essential. However, although LCCA has recognized potential for rationalizing bridge procurement and management decisions its use in this context is far from systematic and the integration of LCCA findings in decisions is often far from robust. Thus, the overall objective of the work underlying this thesis has been to contribute to the development of sustainable bridge infrastructures while optimizing use of taxpayers’ money, by robustly incorporating life-cycle considerations into bridge investment and management decision-making processes.The work has introduced a full scheme for applying LCCA throughout bridges’ entire life-cycle. Several practical case studies have been presented to illustrate how an agency could benefit from use of a bridge management system (BMS) to support decisions related to the management of existing bridges and procure new bridges. Further developments include a comprehensive approach incorporating a novel LCCA technique, “LCC Added-Value Analysis”, which enables procurement of the most cost-efficient bridge design through a fair design-build (D-B) tendering process. A further contribution is a novel, holistic approach designed to enable procurement of bridges with the maximal possible sustainability (life-cycle advantages) under D-B contracts. The approach combines LCC Added-Value analysis with other techniques that make bridges’ aesthetic merit and environmental impact commensurable using an adapted concept named the willingness-to-pay-extra (WTPE).The systematic analytical procedures and potential of LCCA to deliver major savings highlighted in this thesis clearly demonstrate both the feasibility and need to integrate LCCA into bridge procurement and management decisions. This need has been recognized by Trafikverket (the Swedish Transport Administration), which has implemented a software tool developed in the research (BaTMan-LCC) in its bridge and tunnel management system (BaTMan). This thesis introduces readers to the field, considers BaTMan and the bridge stock in Sweden, discusses the developments outlined above and obstacles hindering further implementation of LCCA, then presents proposals for further advances.
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