# Investigating a Toolchain from Trajectory Recording to Resimulation
## 2 Material and Methods
### Traffic Simulation  
For the re-simulation of scenarios, the open-source simulation environment openPASS (open platform for the assessment of safety systems) is used. The platform has been under constant development since 2016, also with the support of the automobile industry and corresponding suppliers. The simulation platform openPASS can be used for stochastic traffic simulation by choosing statistical parameters of the simulated static agents or for the simulation of specific scenarios with dynamic agents. The behavioral models on which the simulation environment is based are the vehicle following model according to [PERSON] [9] and the lane change model according to [PERSON] [33]. The corresponding equations of both models can be found in [34]. These behavioral models were originally designed to represent accident-free traffic. Accordingly, there have to be developments that enable the simulation to generate critical situations, including accidents. With respect to the behavioral models included in openPASS, the simulation platform is able to simulate linear traffic like on highways or interurban roads. The main actions on these types of roads are following other vehicles or changing the lane to overtake other vehicles. For simulating non-linear scenarios like urban intersections, it is expected that the simulation platform needs additional behavioral models for non-linear maneuvers like LTAP or crossing pedestrians. For setting up the simulation, nine config files are needed, including an ASAM OpenDrive file for defining the scenery and an OpenScenario file for defining the positions and routes of the simulated agents. In addition, catalog files are needed for defining the vehicles and the driver properties. Especially the driver properties influence the driving behavior of the simulated agents according to the underlying behavior models. In a slaveConfig file, the simulation is finally set up, and environmental parameters like weather conditions, visibility distances, and friction parameters are set, as well as parameters for spawning agents in the simulation and the name and directory of the simulation output file, although the environmental parameters have no influence on the simulation results for now. ASAM OpenDrive is an open-source, standardized, xml-based language for defining properties of roads and whole road courses. These files can be input files for simulation platforms like openPASS to set up the simulated scenery. As described in the introduction, the geometry of the re-simulated T-junction was used to write such an OpenDrive file. For the simulation environment openPASS, OpenDrive version 1.0 was used. In addition to the OpenDrive standard, ASAM OpenScenario is another open-source, standardized, xml-based language for defining a scenario. For use in openPASS, the OpenScenario file defines the simulated agents, the starting points of them, and the route. All interactions between the simulated agents should result from the behavioral models of the simulation interface openPASS. Without a simulation interface, the OpenScenario file can also be used for defining whole trajectories and storylines of actions and maneuvers at different time steps, such as breaking, lane changes, and overtaking. Due to the preliminaries of the used simulation environment, openPASS, the standard version 1.0 is used. The behavioral models in openPASS (Krauss and Kraizewicz) are especially the models that are defined in the SUMO simulation platform [6]. In addition, the behavioral models were extended by new functions and parameters for generating critical situations and accidents. Such parameters are the cooperative of vehicles for lane changing when a faster vehicle is following, the wish of keeping on the right lane when approximating a slower vehicle, the accepted minimum distance to the vehicle in front dependent on the current velocities of both, and the willingness to violate the speed limit.