New Approach for Evaluate Travel Time Variability and Application for Real Case in Hungary
T Matrai, M Juhasz, BKK Centre for Budapest Transport, HU
Objective is to assess the limitations of CBA methodologies and propose an innovative approach to evaluate TTV in the case of railway projects. Calibration of the model has been carried out. A Hungarian case study was used to apply the new approach.
The infrastructure investments consist of a large part of countries spending. These expenses have risen over the last decade up to 1.2% of the GDP. These investments are important for the economic growth and mainly driven by the public sector. In the current economic crisis, the scarcity of resources are more critical. Decision-makers have to choose carefully among many alternative investment options, including transport investments. The Cost-Benefit Analysis (CBA) approach can help to make these decisions.
Several researches were carried out in order to improve the currently used CBA methodology. Thanks to these researches the CBA is widely accepted and used decision support tool, even if it has its own shortcomings and drawbacks. While the project appraisal guidelines are intended to be both practical and well-grounded in international experience and evaluation research, they have obvious limitations. CBA is applied social science and this is not an exact discipline. It is largely based on approximations, working hypotheses and shortcuts because of lack of data or because of constraints on the resources of evaluators. Therefore a Cost-Benefit Analysis can be only as good as its assumptions are.
Infrastructure investment projects regularly experience cost and time overruns. Researches focused on new infrastructures constructions suggested that misrepresentation and optimum bias are primary causes for these overruns. There was limited attention on infrastructure upgrade projects, despite upgrade works can cause significant disturbance to the existing infrastructure normal operation, especially in rail projects.
Although the travel time savings still one of the main benefits of transport investment projects, there are a lot of critique towards the evaluation of them. There are experts who consider that there is no time savings in long run, hence people have a constant time budget, therefore the higher possible speed is not reduce the time used for travel, but increases the accessibility. The other consideration is that the value of time (VOT) is not constant. Travelers are sensitive to the consequences, such as waiting times, missed connections and arrival at the destination either before or after the desired or expected arrival time. Therefore an aggregated VOT approach is too simplistic and should use heterogeneous values for travel time monetization. The time benefits are traditionally measured as the improvement in journey time. In incorporating reliability, those time benefits need to be split into travel time savings and savings in reliability. A monetary value is then given to time. Both travel time and reliability values will vary across users, trip purpose, and location.
The objective of this paper is to assess the current limitations of Cost-Benefit Analysis (CBA) methodologies applied in Europe and propose an innovative approach to evaluate travel time variability in the case of future railway projects. The calibration of the proposed model was created with a stated-preference survey.
Results with the new model can be shown through an ex-post evaluation of a case study (Modernization of the Sopron - Szombathely - Szentgotthard railway line). In the selected project, the original ex-ante CBA was recreated and a new ex-post evaluation was implemented based on the available information. In the recreated ex-ante CBA the benefit estimated from travel time reliability equals 8 percent of the investment cost. The ex-ante and ex-post results were also compared and further conclusion could be drawn.
Association for European Transport