Urban forest usage and perception of ecosystem services – A comparison between teenagers and adults

We thank Christoph Düggelin and Marc Baume for the interpretation of the photographs and two anonymous reviewers for comments on the manuscript. The project was funded by the Swiss State Secretariat for Education, Research and Innovation SERI, Switzerland (Grant No. C13.0135) as a contribution to the COST Action PF1204 and by the Swiss Federal Office for the Environment, Switzerland (Grant No. 16.0074.PJ / S062-1129).Peer reviewedPublisher PD

Understanding the Value of Travel Time.: Advanced modelling techniques applied to the National German Value of Travel Time and Travel Time Reliability Study

Project appraisal is an essential part of policy making, in transportation and elsewhere. To this end, different valuation methods are used. One of the most important evaluation tool is the Cost-Benefit-Analysis. Often, travel time savings account for the largest share of the gains in Cost-Benefit-Analyses. Therefore, they are a central element of the analyses, making its accurate determination of great importance for transport policy appraisal and investment decisions. The time changes are evaluated using the willingness to pay of travellers to save time resulting in the most important number in transport economics: the value of travel time. The \emph{German Value of Time and Value of Reliability Study} was the first official national study estimating values of travel time for Germany. For this purpose a large nationwide data set was collected. It covered six travel modes and five trip purposes, included several transport related attributes and different kinds of stated preference experiments, as well as two time horizons in the choice experiments. This great complexity and detail and the large sample size allows the investigation of various aspects and perspectives of time valuation. This thesis makes use of this rich data to compare a variety of approaches for travel time valuation, comparing different state-of-the-art model formulations, and covering more controversial topics, such as the use of values of time from long-term decisions. The values of time are derived using various model formulations and splits of the data. The impact of the method on the accuracy and trustworthiness of the estimates is evaluated, and used to make recommendations for future studies. The results show various interesting aspects. First, business as a travel purpose was found to be very special, and should thus ideally be modeled separately. Also shopping trips show different characteristics than the other purposes. Second, the VTT follows systematic patterns with changing agglomeration size, indicating that a differentiation on this level might be beneficial. Differentiating by local income, on the opposite, did not exhibit a recognisable pattern. Using a proven method to estimate the standard error of the estimated VTT, it was shown that for the formulation with the best model fit, a latent class model, accuracy in the VTT estimates was actually worse, illustrating how important error estimates are in the process of selecting the best model. A formulation of the VTT based on long term decisions did not bring any satisfying results. In particular, it seems that the other attributes that were part of the choice were valued much more strongly than changes in travel times. This thesis presents an in-depth and comprehensive evaluation of travel time with data from a national VTT study. The conclusions drawn from the analyses can be used as guidance for future transport project evaluation and policy making

Comparing short- and long-term values of travel time savings derived from a joint modelling framework

The value of travel time is an important element of cost-benefit analysis for appraisal of trans- portation project, by encapsulating the willingness to pay of the population for improvements in the transport system. Those values are typically obtained from mobility choice data, in the form of revealed or stated preference surveys. Although short term decisions, such as route and mode choice, are typically used for this purpose, a growing number of authors is arguing that long term decisions might provide more meaningful values for the evaluation of transportation projects. This paper uses the German Value of Time Study, that contains both short and long term choice experiments, to investigate the impact of different time horizons on the valuation of time. In particular, the availability in the dataset of two different long term experiments (residential and workplace choice) allow to evaluate not only the impact of the time horizon, but of the type of long term decision. Using a joint model including all relevant choice situations, this paper investigates the difference in the valuation of time coming from different kind of choice experiments. The results show that the chosen time horizon does have a significant effect on the valuation of travel time and cost. Another finding is that the type of long term decision and the structure of the choice experiment itself also influence the valuation

Comparing values of travel time obtained from residential, workplace and short-term decisions

The value of travel time (VTT) is an important element cost-benefit analysis of transportation projects, by encapsulating the willingness to pay of the population for improvements in the transport system. Those values are typically obtained from mobility behaviour data, in form of revealed or stated preference survey data. Although short-term decisions are typically used for this purpose, a growing number of authors is arguing that long-term decisions might provide more meaningful values for the evaluation of transportation projects, as those decisions have a longer-lasting effect on the experienced travel times. This paper uses data, which contains both, short- and long-term experiments, to investigate the impact of different time horizons on the valuation of time. In particular, two different long-term experiments (residential and workplace choice) in the dataset allow to evaluate not only the impact of the time horizon, but also the type of long-term decision. Using a joint model including all relevant choice situations, this paper investigates the difference in the valuation of time coming from different kind of choice experiments. The results show that the chosen time horizon does have a significant effect on the valuation of travel time and cost. Another finding is that the type of long-term decision and the structure of the choice experiment itself also influence the valuation. The resulting VTTs with a sharp decline by about a half for commute trips show an opposite effect to previous work. Thus this paper demonstrates the need for refinement of the definition of such a VTT

The German value of time and value of reliability study: The survey work

In 2012 Germany’s Federal Ministry of Transport and Digital Infrastructure (BMVI) initiated several projects in preparation of the new Federal Transport Infrastructure Plan (BVWP) 2030. This included an update of the general methodology and in particular of its cost–benefit analysis which is used to evaluate the effects of hundreds of German infrastructure projects under study. As part of the work the first official values of time (VOT) and values of reliability (VOR) for personal and business travel for Germany derived from a stated preference survey were estimated. From May 2012 until January 2013 nationwide data of more than 3000 participants was collected in a combined two-stage revealed and stated preference survey. This paper discusses the survey design, reports experience of the field phase and analyses the response behaviour of the sample. The stated choice experiments address mode, route, time of departure, workplace and residential location choice. The complex multi-attribute experiments of different types cover various aspects of short and long-term travel choice attributes which the respondent has to take into consideration during his decision process. Furthermore overlapping variables of the stated and revealed preference experiments enabled a joint estimation of the whole data for deriving the VOTs and VORs. Additionally numerous socio-demographic and attitudinal questions plus the large sample size for business and non-business trips make it a unique dataset offering various aspects of travel behaviour and their valuations to explore.ISSN:0049-4488ISSN:1572-943

Producción de materiales con valor agregado a partir de micelio de Aspergillus Niger utilizando agua subcrítica [recurso electrónico]

En el grupo de investigación en termodinámica aplicada se viene desarrollando un proceso para el aislamiento de quitina y complejos quitina-glucano a partir de micelio del hongo Aspergillus Niger, un subproducto de la fabricación industrial del ácido cítrico. El proceso utiliza agua subcrítica; es decir, agua a temperaturas inferiores a la del punto crítico de esta sustancia (374 ºC) y presiones suficientemente altas para que el agua se encuentre en fase líquida a la temperatura de operación. Este proceso presenta ventajas importantes: (1) se lleva a cabo con un solvente muy abundante y económico (agua); (2) requiere tiempos de residencia de pocos segundos; (3) no hay efluentes tóxicos resultantes; y (4) el proceso se lleva a cabo de manera continua, no por tandas. En este trabajo de investigación se modificó sustancialmente un equipo experimental desarrollado en un trabajo anterior, a fin de hacer más sencilla y confiable su operación, y se desarrolló un diseño experimental para explorar el efecto de variables de operación del proceso tales como temperatura y tiempo de residencia sobre el rendimiento y propiedades del producto, el cual corresponde a complejos quitina-glucano. Se obtuvo una gran variedad de productos, cada uno con diferentes propiedades. Se observaron rendimientos entre 30% y 73%, con una proporción de quitina entre 24% y 52%, y pesos moleculares entre 798 y 24812 Da. Posteriormente se realizaron corridas experimentales adicionando hiposulfito de sodio a la mezcla reactiva micelio-agua y se concluyó que la reacción de Maillard tiene una influencia importante en las propiedades y rendimiento del producto. Finalmente, se siguieron procedimientos reportados en la literatura para la fabricación de membranas de nanofibras, y membranas rígidas, a fin de explorar la producción de materiales de alto valor agregado a partir de los complejos quitina-glucano obtenidos. Los resultados muestran que es posible producir nanofibras por medio de ultrasonido, y además que su morfología microscópica y macroscópica depende en gran medida del solvente utilizado en el proceso y de la concentración del soluto

The German value of time (VOT) and value of reliability (VOR) study: The survey work

In 2012 Germany’s Federal Ministry of Transport and Digital Infrastructure (BMVI) initiated several projects in preparation of the new Federal Transport Investment Plan (BVWP) 2030. This included an update of the general methodology and in particular of its cost-benefit analysis (CBA) which is used to evaluate the effects of hundreds of German infrastructure projects under study. As part of the work the first official values of time (VOT) and values of reliability (VOR) for personal and business travel for Germany were estimated. From May 2012 until January 2013 nationwide data of more than 3000 participants was collected in a combined two-stage revealed and stated preference survey. This paper discusses the survey design, reports experience of the field phase and analyses the response behaviour of the sample. The stated choice experiments address mode, route, time of departure, work place and residential/location choice. The complex multi-attribute experiments of different types cover various aspects of short and long-term travel choice attributes which the respondent has to take into consideration during his decision process. Furthermore overlapping variables of the stated and revealed preference experiments are suitable for a joint estimation of the whole data. Additionally numerous socio-demographic and attitudinal questions plus the large sample size for business and non-business trips make it a unique dataset offering various aspects of travel behaviour and its valuation to explore

Second-round effects of carbon fuel taxation in transportation: Inequality in access to alternatives hampers progressiveness

This study analyzes the distributional effects of carbon taxation by also incorporating the potential for behavioral adaptation. When considering these second-round effects, the progressiveness of a revenue-neutral carbon tax is reduced

Investigating preferences for powertrains when buying a car in Germany

Germany's Federal Climate Change Act requires the transport sector to reduce its greenhouse gas emissions by almost half until 2030. The government has set an ambitious goal of increasing the number of fully electric vehicles to 15 million within the same period. Data on the factors influencing the purchase of low- or zero-emission vehicles is still scarce. Based on stated preference data collected in spring 2022, we found that battery electric vehicles are the preferred choice of respondents in the hypothetical situation of buying a new car, but not in the used car market. Our results support the high demand for battery electric vehicles, suggesting that stagnating shares in new registrations could be due to supply shortages. Purchase price and energy costs are the most important factors leading to the choice of an electric powertrain, indicating that purchase premiums currently put into place in Germany are highly effective