VISSIM

Brief Development History

VISSIM was originally developed at the University of Karlsruhe, Germany, with commercial distribution beginning in 1993 by PTV Transworld AG. PTV continues to distribute and maintain VISSIM today, along with several companies around the world. VISSIM is a microscopic, time-step, and behavior-based simulation model developed to analyze the full range of functionally classified roadways and public transportation operations. VISSIM can model integrated roadway networks as well as a full range of transportation modes. VISSIM is a component of a comprehensive software package including modules ranging from demand forecasting to detailed intersection control analysis and simulation. VISSIM can analyze traffic and transit operations under a variety of policy constraints, making it a useful evaluation tool. It features quality animation capabilities.

Car-following Model in VISSIM

VISSIM uses the Wiedemann car following model, which represents the psychological processes of the driver to obtain a desired following distance and relative speed to the lead vehicle. This model is very good at capturing the oscillatory behavior of drivers, which is a key determinant in roadway capacity. The car following model has several parameters which the user may adjust for calibration. Separate car following parameters may be applied to freeway sections, merge sections, and arterial streets. The default values of calibration parameters have been carefully maintained by ongoing studies at the University of Karlsruhe.

Features

VISSIM can be applied to a small area for detailed operational analysis, or to larger areas including freeway and arterial corridors. However, runtime increases significantly with more than 30 actuated-controlled signals are simulated. Dynamic ramp metering and signal control can be evaluated, and external interface through application program interface (API) is possible. The model features an intuitive, easy-to-learn graphic user interface (GUI), with all geometry and traffic control features available for editing via a simple graphical menu. Alternatively, the network data files can be directly modified using a text editor.

Dynamic User Equilibrium Assignment

VISSIM also has a dynamic assignment routine, which can be used to determine the user-equilibrium (UE) driver route choice based on observed travel times through the network, such as routine congestion, bridge closure, or delay at signalized intersections.

Strengths

• VISSIM should be considered the ideal model for urban environments that contain transit or pedestrians (or both). The explicit modeling of pedestrians is crucial for considering their effects in intersection performance due to their interference with turning vehicles, and (significant) losses in green time to the main street on wide arterials. VISSIM has detailed representation of passenger boarding and alighting at bus stops, and available algorithms to emulate the Transit Signal Priority (TSP) operation in the leading traffic signal controllers.
  
• VISSIM offers high-quality 3D-models of vehicles and background features (buildings, trees, landscaping). 3D-animation has been shown to be an effective tool to generate public interest and facilitate participation at meetings.
  
• VISSIM offers interfaces with several other planning and operational models. An automatic intersection generation feature (through VISUM, PTV's traffic assignment model) can be used to create intersection-level detailed data from node-link planning model data. This can allow significant labor savings compared to manually coding these features. This feature is currently under development and refinement, so the reader is recommended to check the features of the latest available software version. Additionally, interfaces are available directly between VISSIM and other models such as SYNCHRO, TEAPAC (a Highway Capacity Analysis tool), and Transyt-7F or Passer-II (by way of TEAPAC)