Kim Bang Salling

Composite decision support by combining cost-benefit and multi-criteria decision analysis

This paper concerns composite decision support based on combining cost-benefit analysis (CBA) with multi-criteria decision analysis (MCDA) for the assessment of economic as well as strategic impacts within transport projects. Specifically a composite model for assessment (COSIMA) is presented as a decision support system (DSS). This COSIMA DSS ensures that the assessment is conducted in a systematic, transparent and explicit way. The modelling principles presented are illuminated with a case study concerning a complex decision problem. The outcome demonstrates the approach as a valuable DSS, and it is concluded that appraisals of large transport projects can be effectively supported using a combination of CBA and MCDA. Finally, perspectives of the future modelling work are given.

Modelling decision support and uncertainty for large transport infrastructure projects: The CLG-DSS model of the Øresund Fixed Link

This paper presents a decision support system, named the CLG-DSS model, which makes it possible for decision makers to assess various uncertainties in project appraisal in a systematic and explicit way. This model, a decision support system (DSS) developed within the Danish Centre for Logistics and Freight Transport (CLG) is based on cost-benefit analysis (CBA) embedded in a wider multi-criteria analysis (MCA) by the use of some principles for composite modelling assessment (COSIMA). The CLG-DSS model is set up to make use of scenario analysis (SA) and Monte Carlo simulation (MCS). A particular concern in the model is the handling of varying information across the assessment criteria and the application of SA to inform the MCS parameter setting. After the presentation of the modelling principles some ex-post case calculations for the Oresund Fixed Link are illuminating different aspects of appraisal uncertainty and thereby, at the same time, demonstrate the features of the CLG-DSS model as a useful decision support tool. It is finally concluded that appraisal of large infrastructure projects can be effectively supported by dealing with uncertainty issues in accordance with the principles described.

Optimization of preventive condition-based tamping for railway tracks

This work considers the scheduling of railway preventive condition-based tamping, which is the maintenance operation performed to restore the track irregularities to ensure both safety and comfort for passengers and freight. The problem is to determine when to perform the tamping on which section for given railway tracks over a planning horizon. The objective is to minimize the Net Present Costs (NPC) considering the following technical and economic factors: 1) track quality (the standard deviation of the longitudinal level) degradation over time; 2) track quality thresholds based on train speed limits; 3) the impact of previous tamping operations on the track quality recovery; 4) track geometrical alignment; 5) tamping machine operation factors and finally 6) the discount rate.

Applying sustainability theory to transport infrastructure assessment using a multiplicative ahp decision support model

AbstractIt is generally expected that the three dimensions of the economy, society and the environment must be included in any measurable sustainability pathway. However, these do not provide much guidance as to how to prioritize impacts within and between the dimensions. A conceptualized approach to sustainability based on the nested model is therefore presented seeking to provide an alternative approach to sustainable transportation assessment, namely the SUSTAIN Decision Support System (DSS) model. This model is based on a review of basic notions of sustainability presented by the Brundtland Commission report, which is used to validate the nested model of sustainability for countries operating under the paradox of affluence. This provides a theoretical rationale for prioritising longer-term ecological integrity over shorter-term economic concerns, in line with the stronger conceptualisation of sustainability supported by ecological economists. This conceptualisation is operationalized by the use of Mul...

Sustainable transport project evaluation and decision support: indicators and planning criteria for sustainable development

This article will expose the necessity for a sustainable planning and decision support framework for transport infrastructure assessment. This will be operationalized through a set of planning criteria and scenario alternatives, which is assessed in the SUSTAIN decision support system (SUSTAIN-DSS) model. A part of the decision support framework will be tested in a case study in Denmark, concerning the problem of congestion on the current bridge crossing Roskilde Fjord in the city of Frederikssund. This article suggests including in a combination both reference class forecasting and quantitative risk analysis as well as sustainable planning criteria in the assessment of the project uncovering new solutions. Thereof the decision support model reveals large potential for the inclusion of planning criteria if the overall objective of development toward a sustainable transportation system is adopted. The SUSTAIN-DSS model rests upon multi-criteria decision analysis and planning workshops in order to combine the use of qualitative and quantitative assessments. This article stresses the necessity of revising current planning paradigms such as cost-benefit analysis (CBA) but also to make clear definitions of the criteria planned for, in order to achieve a sustainable transport system. This alternative approach proves that with relatively small changes in objectives, sustainable development within transport planning can be reached.

Modeling group perceptions using stochastic simulation: scaling issues in the multiplicative ahp

This paper proposes a new decision support approach for applying stochastic simulation to the multiplicative analytic hierarchy process (AHP) in order to deal with issues concerning the scale parameter. The paper suggests a new approach that captures the influence from the scale parameter by making use of probability distributions. Herein, the uncertainty both with regard to the scale and the inherent randomness from the parameter is captured by probabilistic input and output distributions. Provided that each alternative and criteria under consideration are independent it is assumed that the embedded uncertainty from the progression factors remains the same. The result is then an interval estimate for each alternative’s final scores. This can lead to overlapping intervals of scores which may be interpreted as possible rank reversals. Thus, the decision support approach makes it possible to calculate the probability of overlapping for any given set of pairwise comparisons.

Transport project evaluation: feasibility risk assessment and scenario forecasting

AbstractThis paper presents a new approach to transport project assessment in terms of feasibility risk assessment and reference class forecasting. Conventionally, transport project assessment is based upon a Cost-Benefit Analysis (CBA) where evaluation criteria such as Benefit Cost Ratios (BCR) are obtained. Recent research has however proved that substantial inaccuracies are present when obtaining the monetary input to the CBA, particularly as concerns the construction costs and demand forecasts. This paper proposes a new approach in order to address these inaccuracies in a so-called Reference Scenario Forecasting (RSF) frame. The RSF is anchored in the cost-benefit analysis; thus, it provides decision-makers with a quantitative mean of assessing the transport infrastructure project. First, the RSF method introduces uncertainties within the CBA by applying Optimism Bias uplifts on the preliminary construction cost estimates. Hereafter, a quantitative risk analysis is provided making use of Monte Carlo s...

Estimating Railway Infrastructure Project Cost From Transferring Nominal Price To Real Price By Considering The Working Time Possessions

The purpose of the paper is to estimate a railway project construction cost based on the nominal market price. Currently, estimation of project costs within railway infrastructure procurement is particularly challenging due to: 1) construction costs highly depend on possession timeframes and duration and 2) railway construction work costs are not transparent in the market. This paper suggests separating the costs into 3 sub-categories: materials, labor and machinery. Evidently, the materials are further broken down into subcomponents, which then remains fixed, whereas the cost of labor and machinery are varying depending on the working time possessions presented through the closure of the railway line. The effective working hours, type of construction work and construction speed are used as constraints to ensure the track closure plan remains feasible. To demonstrate the approach, a Danish railway construction project, the new line to the fixed link across Fehmarn Belt, is introduced, where it is shown that the non-material cost is about 19% of the total expenditure. By assuming three sets of track blocking scenarios with the same amount of construction work it is proven that, given an optimal track closure plan, the overall cost can be reduced by 2.7%. It can be concluded that the approach using an optimal working possession plan can identify the low-cost track closures.

Assessment of large transport infrastructure projects: The CBA-DK model

The scope of this paper is to present a newly developed decision support model to assess transport infrastructure projects: CBA-DK. The model makes use of conventional cost-benefit analysis resulting in aggregated single point estimates and quantitative risk analysis using Monte Carlo simulation resulting in interval results. The embedded uncertainties within traditional CBA such as ex-ante based investment costs and travel time savings are of particular concern. The methodological approach has been to apply suitable probability distribution functions on the uncertain parameters, thus resulting in feasibility risk assessment moving from point to interval results. Decision support as illustrated in this paper aims to provide assistance in the development and ultimately the choice of action while accounting for the uncertainties surrounding transport appraisal schemes. The modeling framework is illustrated by the use of a case study appraising airport and runway alternatives in the capital of Greenland - Nuuk. This study has been conducted in corporation with the Home Rule Authorities of Greenland.