Traffic flow model and signal control

Vissim is based on a traffic flow model and the signal control. These exchange detector readings and signaling status.

You can run the traffic flow simulation of vehicles or pedestrians as animation in Vissim. You can clearly display many important vehicular parameters in tables or windows or you can output them in files or databases, for example, travel time distributions and delay distributions differentiated by user groups.

The traffic flow model is based on a car-following model (for the modeling of driving in a platoon on a single lane) and on a lane changing model.

External programs for signal control model the traffic-dependent control logic units. The control logic units query detector readings in time steps of one to 1/10 second. You can define the time steps for that reason and they depend on the signal control type. Using detector readings, e.g. occupancy and time gap data, the control logic units determine the signaling status of all signals for the next time step and deliver them back to the traffic flow simulation. Vissim can use multiple and also diverse external signal control programs in one simulation, for example, VAP, VSPLUS.

Communication between traffic flow model and traffic signal control:

Traffic flow simulation with PTV Vissim
 

 

 Traffic flow model

simulates the movement of:

  • Cars
  • HGV
  • Buses
  • Trams
  • Bikes
  • Pedestrians

 

Detector values

Signal states

 Signal control

models:

  • Fixed-time controls or
  • traffic-actuated controls

 

 

Analysis and evaluation of traffic simulation

Vehicle-related data

  • Travel times
  • Traffic volumes
  • Emissions

Control-related data

  • Green time distribution
  • Reasons for signal state changes

Superordinate topic:

Basics