02 Fakultät Bau- und Umweltingenieurwissenschaften

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/3

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Institute: search.filters.UBSInstitut.Institut für Straßen- und VerkehrswesenPublication Type: search.filters.UBSTyp.Zeitschriftenartikel

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    Impacts of highly automated vehicles on travel demand : macroscopic modeling methods and some results
    (2021) Sonnleitner, Jörg; Friedrich, Markus; Richter, Emely
    Automated vehicles (AV) will change transport supply and influence travel demand. To evaluate those changes, existing travel demand models need to be extended. This paper presents ways of integrating characteristics of AV into traditional macroscopic travel demand models based on the four-step algorithm. It discusses two model extensions. The first extension allows incorporating impacts of AV on traffic flow performance by assigning specific passenger car unit factors that depend on roadway type and the capabilities of the vehicles. The second extension enables travel demand models to calculate demand changes caused by a different perception of travel time as the active driving time is reduced. The presented methods are applied to a use case of a regional macroscopic travel demand model. The basic assumption is that AV are considered highly but not fully automated and still require a driver for parts of the trip. Model results indicate that first-generation AV, probably being rather cautious, may decrease traffic performance. Further developed AV will improve performance on some parts of the network. Together with a reduction in active driving time, cars will become even more attractive, resulting in a modal shift towards car. Both circumstances lead to an increase in time spent and distance traveled.
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    Considerations about the quality assessment of travel time and travel distance distributions in transport modelling : a proposal for a standardized methodology
    (2020) Pestel, Eric
    In travel demand modelling, trip distance distributions or trip time distributions are used to evaluate how well a model fits with observed sample data. Therefore, the comparison of distributions is an essential part in the model validation process. Despite its importance, the common modelling guidelines from the UK, the USA or Austria provide little information about the correct structure and handling of such distributions. Likewise, common statistical methods are not practicable for the validation of transport models. This lack of rules leads to individual solutions, which complicate a model validation and the comparison of models. For example, when comparing two distributions the quality indicator strongly depends on the number of classes. Therefore, guidelines for model validation need to suggest an appropriate way to determine the number of classes. The paper suggests a method for evaluating trip distance distributions and trip time distributions within the model validation process of a travel demand model. It proposes (a) indicators for a classification which consider mode-specific trip distances and trip times (b) a generic classification method based on an equiquantile class width, quality indicators for comparing two distributions and (c) to use relative frequencies instead of absolute frequencies for the calculation of the quality indicators.
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    Verkehrsinformationssysteme
    (2000) Kühne, Reinhart D.
    Der direkte Zugang zur Umwelt, zu deren Mechanismen, Materialeigenschaften und zu der dahinterstehenden Technik tritt in den Hintergrund und wird abgelöst durch eine Welt, in der Kommunikationstechnik und Informationstechnik in der Software und virtuelle Realität die entscheidende Rolle spielen. Der Wandel der Technik wird wahrgenommen als ein Wandel der technischen Entwicklungen vom mechanischen Einzelobjekt zum vernetzten Transport und Informationssystem. Dieser Paradigmenwechsel ist zu bedenken, wenn neue Entwicklungen wie Verkehrsinformationssysteme betrachtet werden. Diese neuen Entwicklungen sollen im folgenden in ihren technischen Zusammenhang gestellt und anhand von drei Thesen erläutert werden.
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    Vehicle scheduling for on-demand vehicle fleets in macroscopic travel demand models
    (2021) Hartleb, Johann; Friedrich, Markus; Richter, Emely
    The planning of on-demand services requires the formation of vehicle schedules consisting of service trips and empty trips. This paper presents an algorithm for building vehicle schedules that uses time-dependent demand matrices (= service trips) as input and determines time-dependent empty trip matrices and the number of required vehicles as a result. The presented approach is intended for long-term, strategic transport planning. For this purpose, it provides planners with an estimate of vehicle fleet size and distance travelled by on-demand services. The algorithm can be applied to integer and non-integer demand matrices and is therefore particularly suitable for macroscopic travel demand models. Two case studies illustrate potential applications of the algorithm and feature that on-demand services can be considered in macroscopic travel demand models.