Ilka Ehreke

Valuing Travel Time Savings: Case of Short-Term or Long-Term Choices?

Most value of time studies make use of stated preference data framed around short term decisions such as route choice. However, except in the presence of toll roads, most travelers only have the ability to really trade time and money in a longer term setting, such as when changing residential or employment location. In this paper, the authors make use of a unique dataset which presented respondents with both short term and long term decisions. The former involved trading between travel time and travel cost, while the latter looked at changes in employment. The authors find substantial differences in the valuations coming out of these two types of experiments. In common with many other studies, there are also differences depending on whether willingness to accept or willingness to pay scenarios are presented in the short term settings, but the authors additionally note that the type of scenario shown in the short term choices has an impact on the valuations in the long term settings, which are always framed as a willingness to accept setting.

Reliability in the German value of time study

The German Federal Ministry of Transport and Digital Infrastructure is currently preparing the 2015 Federal Transport Investment Plan. Because this effort includes an update to the overall methodology of the ministrys cost–benefit analysis, both the value of reliability (VOR) and the value of travel time (VOT) for personal and business travel will be estimated. The VOT will replace a set of existing values, but the VOR will be estimated for the first time because they are not yet incorporated in the standard appraisal. A two-stage approach was used for data collection: first respondents reported about current trips (revealed preference), and then these responses were systematically varied to become the basis for stated preference experiments. This paper presents the findings of estimating the VOR. In the stated preference experiments the reliability of the travel modes was presented with different formats. The final model formulation differed in the definition of reliability for private and public transport. For car trips, saving travel time had more value for the respondents than reducing the variability. The calculated VOR for the mean expected unscheduled delay of public transport trips was slightly lower than the VOT; this result indicates that the reliability was less important to the respondents than the relevant travel time saving. A mean expected unscheduled delay of 1 min and 1 min of standard deviation are almost equivalent to 1 min of travel time saving (reliability ratio). Because this was the first official estimation of VOR and VOT for Germany, the values should be reconsidered and updated on a regular basis.

Modellierung von Arbeitsplatzentscheidungen in Mobilitätsbiographien

Mobilitatsbiographien, das heist die Analyse des Verkehrsverhaltens und der Verfugbarkeit von Mobilitatswerkzeugen im Lebensverlauf, ist ein relativ neues Feld in der Verkehrsforschung. Die Erwerbsbiographien sind als Teil von ihnen zu verstehen, auch wenn sie ein eigenes Interessengebiet darstellen. In einer Retrospektivbefragung der TU Dortmund werden zusammen mit der ETH Zurich und der Goethe Universitat Frankfurt Informationen zu den individuellen Mobilitatsbiographien von drei Generationen eines Haushaltes erfasst. Anhand dieses umfangreichen Datensatzes werden mithilfe einer Uberlebenszeit-Analyse fur rekurrente Ereignisse Einflusse auf die Entscheidung fur einen Arbeitswegwechsel, sowie Unterschiede zwischen Generationen und Geschlechtern im Zeitverlauf statistisch analysiert. Neben Generationeneffekten konnte der Effekt von sogenannten Schlusselereignissen (key events) in den Daten nachgewiesen werden. Ebenso konnte die starke Interdependenz von Arbeitsplatz- und Wohnortwahl gezeigt werden. Dies bestatigt die Vermutung, dass sich gewisse Prozesse im Lebensverlauf parallel bewegen.