Institut Bauingenieurwesen

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A new approach for the description of discharge extremes in small catchments
(26.04.2017) Pavia Santolamazza, Daniela; Lebrenz, Henning; Bárdossy, András
06 - Präsentation
A Virtual reality experiment to study citizen perception of future street scenarios
(SSRN, 31.03.2023) Sánchez-Vaquerizo, Javier Argota; Hausladen, Carina Ines; Mahajan, Sachit; Matter, Marc; Siebermann, Michael; van Eggermond, Michael; Helbing, Dirk
The current allocation of street space is based on expected vehicular peak-hour flows. Flexible and adaptive use of this space can respond to changing needs. To evaluate the acceptance of flexible street layouts, several urban environments were designed and implemented in virtual reality. Participants explored these designs in immersive virtual reality in a 2x3 mixed factorial experiment, in which we analysed self-reported, behavioural and physiological responses from participants. Distinct communication strategies were varied between subjects. Participants' responses reveal a preference for familiar solutions. Unconventional street layouts are less preferred, perceived as unsafe and cause a measurably greater stress response. Furthermore, information provision focusing on comparisons led participants to focus primarily on the drawbacks, instead of the advantages, of novel scenarios. When being able to freely express thoughts and opinions, participants were focused more on the impact of the space on behaviour rather than the objective physical features themselves. Especially, this last finding suggests that it is vital to develop new street scenarios in an inclusive and democratic way: the success of innovating urban spaces depends on how well the vast diversity of citizens' needs is considered and met.
05 - Forschungs- oder Arbeitsbericht
A virtual reality experiment to study pedestrian perception of future street scenarios
(Nature, 2024) Argota Sánchez-Vaquerizo, Javier; Hausladen, Carina I.; Mahajan, Sachit; Matter, Marc; Siebenmann, Michael; van Eggermond, Michael; Helbing, Dirk [in: Scientific Reports]
The current allocation of street space is based on expected vehicular peak-hour flows. Flexible and adaptive use of this space can respond to changing needs. To evaluate the acceptability of flexible street layouts, several urban environments were designed and implemented in virtual reality. Participants explored these designs in immersive virtual reality in a mixed factorial experiment, in which we analysed self-reported, behavioural and physiological responses from participants. Distinct communication strategies were varied between subjects. Participants’ responses reveal a preference for familiar solutions. Unconventional street layouts are less preferred, perceived as unsafe and cause a measurably greater stress response. Furthermore, information provision focusing on comparisons lead participants to focus primarily on the drawbacks, instead of the advantages of novel scenarios. When being able to freely express thoughts and opinions, participants are focused more on the impact of space design on behaviour rather than the objective physical features themselves. Especially, this last finding suggests that it is vital to develop new street scenarios in an inclusive and democratic way: the success of innovating urban spaces depends on how well the vast diversity of citizens’ needs is considered and met.
01A - Beitrag in wissenschaftlicher Zeitschrift
Aktivitätenbasierte Verkehrsmodelle
(Bundesamt für Strassen, 12.12.2021) Vitins, Basil; Erath, Alexander; Fellendorf, Martin; Arendt, Michael
05 - Forschungs- oder Arbeitsbericht
Aktivitätenbasierte Verkehrsmodelle: Methoden, Anwendungen, Vor- und Nachteile
(Schweizerischer Verband der Strassen- und Verkehrsfachleute, 2022) Erath, Alexander; Vitins, Basil; Fellendorf, Martin; Arendt, Michael [in: Strasse und Verkehr]
Aktivitätenbasierte Verkehrsmodelle (ABM) sind ein vielversprechender Ansatz der Verkehrsmodellierung. Gegenüber den in der Praxis mehrheitlich eingesetzten aggregierten Modellansätzen bieten ABM verschiedene Vorteile. ABM erlauben vielseitigere Auswertungsmöglichkeiten und flexiblere, methodisch konsistentere Abbildungen von intermodalen Wegeketten – zum Beispiel für ÖV- oder Langsamverkehrsstudien – und zeitlich dynamischen Massnahmen, zum Beispiel Mobility Pricing. Gleichzeitig sind ABM in der Praxis bisher noch weniger etabliert und stellen höhere Anforderungen bei der Modellierung. Im Rahmen eines SVI-Forschungsprojekts wurden Voraussetzungen sowie Vor- und Nachteile des Einsatzes von ABM untersucht, um Modellbetreibern eine Entscheidungshilfe zu bieten.
01B - Beitrag in Magazin oder Zeitung
Analyse der Relevanz von weg- und tourenbasierten Verkehrsmittelwahlansätzen am Beispiel eines aggregierten und eines aktivitätenbasierten Verkehrsmodells der Stadt Halle
(Hochschule für Architektur, Bau und Geomatik FHNW, 03.03.2023) Cachaco, Fabio; Erath, Alexander
Die Masterarbeit untersucht die Relevanz und Auswirkung von weg- und tourenbasierten Verkehrsmittelwahlansätzen. Hierzu erfolgt zunächst eine qualitative Beschreibung der Wirkungsweise verschiedener Ansätze zur Modellierung der Verkehrsmittelwahl. Der Schwerpunkt wird insbesondere auf den Aggregation Bias und die Nutzenfunktion gelegt. Im Rahmen von Fallstudien mit synthetischen Daten und einem Verkehrsmodell erfolgt eine quantitative Abschätzung der Relevanz des Aggregation Bias.
11 - Studentische Arbeit
Analysis of the resolution of precipitation data required to obtain robust results from a hydrodynamic sewer network model
(19.04.2024) Rabiei, Ehsan; Hoppe, Holger; Lebrenz, Henning
The need for precipitation data for calibrating hydrodynamic sewer network models is often compromised by using the nearest available rain gauges to study area. Due to the scarcity and irregular locations of the rain gauges, this way of satisfying the need for precipitation data can lead to incorrect conclusions with respect to the temporal and spatial patterns of precipitation, depending on the location of the rain gauges in the study area. Recent developments in the field of precipitation measurement by means of weather radar data open up new possibilities for the use of such data sources in hydrodynamic sewer network models. Even though weather radar provides precipitation information with a high temporal and spatial resolution, the raw radar data contains several sources of error and is inaccurate. The radar data are therefore often corrected and merged with ground measurements. The main objective of this study is to investigate the resolution of precipitation data required to obtain robust results in a hydrodynamic channel network model. The study area is a small catchment close to Munich in Bavaria, Germany. Data from the Isen weather radar station of the German Weather Service (DWD), which is located around 33 km from the study area, was used. Following the objectives of this study, various weather radar data products were processed in order to be used as input for a hydrodynamic sewer network model. The data with a temporal resolution of 5 minutes to 1h and a spatial resolution of 250 m x 250 m up to 1.000 m x 1.000 m form the basis for creation of datasets to be investigated. It has been observed that the use of high-resolution precipitation data leads to better model results, especially when the data is merged with rain gauges. However, it should be noted that the quality of the model results does not decrease linearly when the resolution of the precipitation data is reduced.
06 - Präsentation
Applying bias correction for merging rain gauge and radar data
(Elsevier, 13.01.2015) Rabiei, Ehsan; Haberlandt, Uwe [in: Journal of Hydrology]
Weather radar provides areal rainfall information with very high temporal and spatial resolution. Radar data has been implemented in several hydrological applications despite the fact that the data suffers from varying sources of error. Several studies have attempted to propose methods for solving these problems. Additionally, weather radar usually underestimates or overestimates the rainfall amount. In this study, a new method is proposed for correcting radar data by implementing the quantile mapping bias correction method. Then, the radar data is merged with observed rainfall by conditional merging and kriging with external drift interpolation techniques. The merging product is analysed regarding the sensitivity of the two investigated methods to the radar data quality. After implementing bias correction, not only did the quality of the radar data improve, but also the performance of the interpolation techniques using radar data as additional information. In general, conditional merging showed greater sensitivity to radar data quality, but performed better than all the other interpolation techniques when using bias corrected radar data. Furthermore, a seasonal variation of interpolation performances has in general been observed. A practical example of using radar data for disaggregating stations from daily to hourly temporal resolution is also proposed in this study.
01A - Beitrag in wissenschaftlicher Zeitschrift
Areal rainfall estimation using moving cars. Computer experiments including hydrological modeling
(Copernicus, 26.09.2016) Rabiei, Ehsan; Haberlandt, Uwe; Sester, Monika; Fitzner, Daniel; Wallner, Markus [in: Hydrology and Earth System Sciences]
The need for high temporal and spatial resolution precipitation data for hydrological analyses has been discussed in several studies. Although rain gauges provide valuable information, a very dense rain gauge network is costly. As a result, several new ideas have emerged to help estimating areal rainfall with higher temporal and spatial resolution. Rabiei et al. (2013) observed that moving cars, called RainCars (RCs), can potentially be a new source of data for measuring rain rate. The optical sensors used in that study are designed for operating the windscreen wipers and showed promising results for rainfall measurement purposes. Their measurement accuracy has been quantified in laboratory experiments. Considering explicitly those errors, the main objective of this study is to investigate the benefit of using RCs for estimating areal rainfall. For that, computer experiments are carried out, where radar rainfall is considered as the reference and the other sources of data, i.e., RCs and rain gauges, are extracted from radar data. Comparing the quality of areal rainfall estimation by RCs with rain gauges and reference data helps to investigate the benefit of the RCs. The value of this additional source of data is not only assessed for areal rainfall estimation performance but also for use in hydrological modeling. Considering measurement errors derived from laboratory experiments, the result shows that the RCs provide useful additional information for areal rainfall estimation as well as for hydrological modeling. Moreover, by testing larger uncertainties for RCs, they observed to be useful up to a certain level for areal rainfall estimation and discharge simulation.
01A - Beitrag in wissenschaftlicher Zeitschrift
Assessing cycling skills in Switzerland
(11/2022) van Eggermond, Michael; Schaffner, Dorothea; Studer, Nora
For many people, safety concerns are a major barrier to ride a bicycle. Indeed, cyclists bear a higher risk than most other types of road users. Improving cycling infrastructure is the most obvious and effective way to increase cycling safety. This paper sets out to identify skills required by cyclists to navigate safely through an urban environment in Switzerland. We set out to identify situations that might result in accidents and require specific competences. This research has shown that there is potential to further develop cyclists’ skills. Rather than focusing on motoric skills or presenting simple situations, we advise that skills should be trained based on more complex situations. These situations include turning, branching, maintaining distance from parked cars and recognising right of way in residential areas.
04B - Beitrag Konferenzschrift
Begleitstudie zum Tier-Pilotprojekt in Riehen
(Institut Bauingenieurwesen, Hochschule für Architektur, Bau und Geomatik FHNW, 16.01.2023) Erath, Alexander; van Eggermond, Michael
05 - Forschungs- oder Arbeitsbericht
Bestimmung von Velohauptrouten im Kanton Basel-Stadt
(Hochschule für Architektur, Bau und Geomatik FHNW, 21.08.2024) Fiabane, Noè; Erath, Alexander
Im Rahmen des ersten Vertiefungsprojektes im MSE befasst sich diese Arbeit mit der Bestimmung von Velohauptrouten. Durch die Auswertung von Velonetzen im In- und Ausland, das Studium von Fachliteratur und Interviews mit Expertinnen und Experten wurde eine Methodik entwickelt, um Velohauptrouten festzulegen. Diese Methodik wurde am Beispiel vom Kanton Basel-Stadt auf der Ebene des Netzentwurfes angewandt. Anhand des konkreten Beispiels Basel-Stadt zeigte sich, dass die Bestimmung von Velohauptrouten sowohl intuitiv als auch herausfordernd ist. Die Routenführung auf der Ebene der Hauptverbindungen ist in vielen Fällen durch äussere Rahmenbedingungen vorgegeben. Dazu gehören Zwangspunkte wie die Rheinbrücken sowie städtebauliche Hauptachsen. Wo eine solche Führung nicht offensichtlich ist, wurde ein Bewertungsschema entwickelt, das sich auf die Anforderungen des Gesetzes über Velowege und dessen Praxishilfe stützt. Bei unklaren Teilabschnitten einer Route konnte so mittels Varianten unterschiedliche Routenführungen erstellt werden. Anschliessend wurde durch das Bewertungsschema die Bestvariante eruiert und einer Sensitivitätsanalyse unterzogen. Aufgrund der zeitlichen Rahmenbedingungen wurde dies bei vier Abschnitten durchgeführt.
11 - Studentische Arbeit
Calibration of a regional agent-based travel demand model to simulate the spread of COVID-19
(2021) Mesaric, Raphael; Erath, Alexander
The recent COVID-19 pandemic has shown the need of readily available tools to simulate the spreading of infectious diseases and assess the potential impact of policy measures aimed at the containment of the disease. The most common approach in epidemiology is to use compartmental models which model disease spreading as a series of stocks (compartments) and flows. The most basic version considers three compartments: susceptible, infectious and recovered. One of the core assumptions of these models, however, is a homogeneous population which is a serious limitation when it comes to clustered outbreaks. The research at hand uses an agent-based travel demand model (MATSim) coupled with a recently developed extension (EpiSim) to simulate the spread of the pandemic by tracking the interactions of agents und subsequently identifying infections by following their contact network. This overcomes the compartmental assumption of the previous models. In this presentation, we summarize the calibration results of the EpiSim model which is based on the regional activity- and agent-based travel demand model of the trinational region around Basel. The calibration procedure is based on data on case numbers and hospitalisations from three countries (Switzerland, Germany and France) at different spatial resolution. The underlying models account for the effect of border closures and spatially varying restrictions to limit the spread of COVID-19. In contrast to existing studies, this model pays particular attention to disease import through external traffic from outside the model area as well as cross-border travel demand.
06 - Präsentation
Continuously-fed gravity currents propagating over a finite porous substrate
(American Institute of Physics, 31.12.2019) Venuleo, Sara; Pokrajac, Dubravka; Schleiss, Anton J.; Franca, Mário J. [in: Physics of Fluids]
We present the results of laboratory investigations of continuously-fed density currents that propagate first over a smooth horizontal bed and then over a porous substrate of limited length. Inflow discharge, initial excess density, and substrate porosities are varied. Density measurements, acquired through an image analysis technique, are performed above the porous layer simultaneously with quasi-instantaneous vertical velocity profiles. After a first phase in which the current sinks into the substrate, freshwater entrainment from the bed begins and, gradually, a mixing layer forms at the interface between the surface flow and the porous bed. Shear-driven and Rayleigh-Taylor instabilities rule the dynamics of this mixing layer. The porous boundary effects are observed in the vertical distributions of both density and velocity, especially in the near-bed region. Here, larger flow velocities are recorded over porous substrates. We argue that these are due to the presence of a longitudinal pressure gradient, which in turn is a consequence of the current mass loss. Its presence over the porous substrate is proved by the current interface longitudinal slope. However, other effects of the presence of the porous substrate, such as the relaxation of the no-slip boundary condition and the bed-normal momentum exchange, also affect the velocity field. The turbulent structure changes significantly over the porous substrate: while streamwise turbulence decreases, shear and bed-normal Reynolds stresses increase in large part of the current depth. Buoyancy instabilities further enhance the bed-normal momentum flux and, in the near-bed region, contribute to turbulent kinetic energy generation together with shear.
01A - Beitrag in wissenschaftlicher Zeitschrift
Depth-averaged momentum equation for gravity currents with varying density. Coefficient in pressure term
(Taylor & Francis, 31.07.2017) Pokrajac, Dubravka; Venuleo, Sara; Franca, Mário J. [in: ISH Journal of Hydraulic Engineering]
Gravity currents are often modelled by means of shallow water equations (SWEs). In these models, simplifications such as the consideration of a constant layer-averaged density are common. This note presents the complete and general derivation of a 2D depth-averaged momentum equation for gravity currents with density and velocity varying in the bed-normal direction. Special attention is given to the pressure term which is evaluated for constant, linear and exponential density profile. The shape of the density profile has implications for the momentum balance: the assumption of constant density leads to an overestimation of the driving force due to pressure gradient by a factor of 33% for linear density profile and up to 50% for an exponential profile. It also leads to an overestimation of celerity in numerical models based on traditional SWEs by factor of 22% and around 40% for linear end exponential density profiles respectively.
01A - Beitrag in wissenschaftlicher Zeitschrift
Destination choice modeling with spatially distributed constraints
(University of Minnesota, 03.07.2023) Vitins, Basil; Erath, Alexander [in: Journal of Transport and Land Use]
01A - Beitrag in wissenschaftlicher Zeitschrift
Elemente der Werkstoffformulierung für Beton und deren Verwendung in der Kurzzeitdynamik
(Ernst & Sohn, 2007) Schuler, Harald [in: Beton- und Stahlbetonbau]
01B - Beitrag in Magazin oder Zeitung
Estimation of the Variogram Using Kendall's Tau for a Robust Geostatistical Interpolation
(14.01.2017) Lebrenz, Henning; Bárdossy, András [in: Journal of Hydrologic Engineering]
The estimation of an appropriate variogram is a crucial step toward the description of spatial dependence, the geostatistical interpolation of environmental variables, and the subsequent hydrological engineering. The classical variogram in the literature ideally necessitates a normal distribution of the variable and is not robust against outliers within the data. These presumptions are hardly given under empirical conditions and, therefore, a new estimation method is proposed for the variogram. The new method is based on the description of spatial dependence by the robust rank coefficient τ and generalizes the method from the Gaussian to the general case of empirical distributions. The conversion of the robust estimate using a Monte-Carlo simulation and subsequent quantile-quantile transformation with the empirical marginal distribution performs the generalization. Monthly precipitation data from South Africa serve as the variable and were artificially contaminated with outliers. The effects on the variogram and subsequent geostatistical interpolation were investigated for the proposed, classical, and four existing robust variogram models in this comparative study. The investigation revealed that the proposed variogram describes a distinct spatial dependence structure under empirical conditions, which is robust against outliers. The cross validation of the linear estimator demonstrates that the proposed variogram tends to improve the bias and spread of the resulting error distribution, and hence the quality of the geostatistical interpolation.
01A - Beitrag in wissenschaftlicher Zeitschrift
Evaluation and acceptance of an online cycling training for adults to master complex traffic situations
(16.11.2023) van Eggermond, Michael; Studer, Nora; Johnson, Lucy; Knecht, Leah; Schaffner, Dorothea
06 - Präsentation
Evaluation of an experimental Method via numerical Simulations
(CRC Press, 2007) Schuler, Harald; Carpinteri, Alberto; Gambarova, Pietro G.; Ferro, Giuseppe; Plizzari, Giovanni [in: Fracture Mechanics of Concrete and Concrete Structures. Proceedings of the 6th International Conference on Fracture Mechanics of Concrete and Concrete Structures, Catania, Italy, 17-22 June 2007]
04B - Beitrag Konferenzschrift

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