There is consensus in industry and academia that Highly Automated Vehicles (HAV) and Connected Automated Vehicles (CAV) will be launched into the market in the near future due to emerging autonomous driving technology. In this paper, a mixed traffic simulation framework that integrates vehicle models with different automated driving systems in the microscopic traffic simulation was proposed. Currently, some of the more mature Automated Driving Systems (ADS) functions (e.g., Adaptive Cruise Control (ACC), Lane Keeping Assistant (LKA), etc.) are already equipped in vehicles, the very next step towards a higher automated driving is represented by Level 3 vehicles and CAV which show great promise in helping to avoid crashes, ease traffic congestion, and improve the environment. Therefore, to better predict and simulate the driving behavior of automated vehicles on the motorway scenario, a virtual test framework is proposed which includes the Highway Chauffeur (HWC) and Vehicle-to-Vehicle (V2V) communication function. These functions are implemented as an external driver model in PTV Vissim. The framework uses a detailed digital twin based on the M86 road network located in southwestern Hungary, which was constructed for autonomous driving tests. With this framework, the effect of the proposed vehicle models is evaluated with the microscopic traffic simulator PTV Vissim. A case study of the different penetration rates of HAV and CAV was performed on the M86 motorway. Preliminary results presented in this paper demonstrated that introducing HAV and CAV to the current network individually will cause negative effects on traffic performance. However, a certain ratio of mixed traffic, 60% CAV and 40% Human Driver Vehicles (HDV), could reduce this negative impact. The simulation results also show that high penetration CAV has fine driving stability and less travel delay.
As the complexity of automated driving systemss (ADSs) with automation levels above level 3 is rising, virtual testing for such systems is inevitable and necessary. The complexity of testing these levels lies in the modeling and calculation demands for the virtual environment, which consists of roads, traffic, static and dynamic objects, as well as the modeling of the car itself. An essential part of the safety and performance analysis of ADSs is the modeling and consideration of dynamic road traffic participants. There are multiple forms of traffic flow simulation software (TFSS), which are used to reproduce realistic traffic behavior and are integrated directly or over interfaces with vehicle simulation software environments. In this paper we focus on the TFSS from PTV Vissim in a co-simulation framework which combines Vissim and CarMaker. As it is a commonly used software in industry and research, it also provides complex driver models and interfaces to manipulate and develop customized traffic participants. Using the driver model DLL interface (DMDI) from Vissim it is possible to manipulate traffic participants or adjust driver models in a defined manner. Based on the DMDI, we extended the code and developed a framework for the manipulation and testing of ADSs in the traffic environment of Vissim. The efficiency and performance of the developed software framework are evaluated using the co-simulation framework for the testing of ADSs, which is based on Vissim and CarMaker.
18 July 2023 in Transportation Research Record: Journal of the Transportation Research Board
In many moderately sized European cities, the public transport systems based on trams and buses are operating at their capacity limits. Ropeways have proved to be a suitable transit extension in several Latin American cities. Few travel demand models attempt to forecast the impact of urban ropeways. So far, all of these models do not consider the specific properties of a ropeway. This paper seeks to estimate a mode choice model that includes a ropeway as a separate transport system. Relative to bus operation in European cities, ropeways promise improved timetable keeping, with fewer delays at the start because of high service rates, and they also offer improved passenger comfort with higher capacities. These benefits must be reflected in the travel demand model by mode-specific parameter settings that are estimated based on a survey. A stated choice experiment was conducted, in which respondents compared realistic trip situations using a ropeway with traditional urban transport modes, with aspects including access and egress time, waiting time, travel time, travel costs, reliability, and crowding. The situations of choice were selected from observed trip data to be as realistic as possible. Using a mixed logit (ML) model, the parameter estimation indicates that crowding and reliability as well as the personal attitude of potential users have a statistically significant influence on the choice behavior of people in Graz, a moderately sized city in Austria.
4 February 2023 in Transportation Research Record: Journal of the Transportation Research Board
Mobile phone data (MPD) has been used in various studies to analyze human travel behavior in time and space. While the pure number of available trips is promising, data quality and the information density of each individual trajectory is relatively low. Travel mode detection of MPD-trajectories is a challenging task, since geographic location data is noisy and the events within a trajectory are irregular (event-based instead of time discrete). In this paper, we present a method to identify travel modes typically observed in urban areas, such as walking, bicycle, tram, bus, and car. The method requires concise network graphs for each mode. Annotated GPS trajectories were collected from volunteers as ground truth to train and validate various machine learning algorithms. The cleaned trajectories of the MPD are segmented into individual trips, which are mapped on the network graphs using a map-matching algorithm. Various features, such as trip distance and travel speed, were analyzed to identify the most suitable features for classifying the available modes with a random forest (RF) and a support-vector machine algorithm. With the RF algorithm, about 80% of all trips were associated to the correct mode. Since the total dataset was only comprised of about 600 trips, which then needed to be split into an evaluation dataset and a training dataset, we suspect the accuracy of the method will increase with more data. Based on the results, this work presents a proof of concept for determining the travel mode of MPD-trajectories.
Electrification, automation of vehicle control, digitalization and new mobility are the mega trends in automotive engineering and they are strongly connected to each other