Defining global model parameters

For each type of pedestrians, global model parameters can be set, apart from model parameters. Global model parameters are used as default values when you define pedestrian routes. When changing global model parameters, you do not change the parameters of the pedestrian routes already defined.

• grid_size: Search neighborhood grid size (Selecting network settings for pedestrian behavior)

With this parameter you can define the maximum distance at which pedestrians have an effect upon each other. Default 5 m.

The pedestrians are stored in a grid with cells of size grid_size x grid_size square meters. A pedestrian in a cell interacts with pedestrians from the following 8 cells only:

• the 4 adjoining cells
• the 4 cells which hit a pedestrian's cell with one of their corners.

Tip: Your Vissim installation provides example data and a description for testing with these parameters. ..\Examples Training\Pedestrians\Parameter Demonstration\02 - Grid Size

• routing_obstacle_dist: Default obstacle distance (Selecting network settings for pedestrian behavior)

This parameter only has an effect on the calculation of the static potential. It is not considered in the calculation of the dynamic potential. The static potential is also called distance potential or distance look-up table. When calculating the value of the static potential the value of grid cells which are close to a wall increases, in addition to the value resulting from the distance from the exit. This ensures that the pedestrians choose a wide corridor rather than a narrow passage when they have both options on their way from A to B, and neither option is shorter than the other. Generally, the pedestrians maintain a certain distance to the walls. This parameter specifies the distance, up to which the nearby walls have a bearing on the distance potential. Default 0.50 m.

Tip: Your Vissim installation provides example data and a description for testing with these parameters. ..\Examples Training\Pedestrians\Parameter Demonstration\02 - Grid Size

• cell_size: Cell size (Attributes of pedestrian route locations)

This parameter defines the distances of control points to be set for the calculation of distances to a destination area. Default 0.15 m.

• never_walk_back: Option Never walk backwards (Selecting network settings for pedestrian behavior)

Use this parameter to define whether pedestrians should stop, if the direction of movement and the desired direction differ by more than 90° (1 = on, 0 = off):

• No calculation, if the default value is 0.
• With parameter value 1, the scalar product is derived from the desired direction and the calculated speed: With a negative value, the pedestrian will stop.

Tip: In the following directory you will find sample files, which illustrate the mode of action of these parameters, as well as a description of the mode of action of the parameters in the modeling of the dynamic potential: ..\Examples Training\Pedestrians\Enhanced Routing\Dynamic Potential

• Dynamic_potential_g: g (general strength) (Defining the Dynamic Potential for a static pedestrian route)

This parameter defines how in general the delay for an occupied grid cell is estimated in relation to an unoccupied one. Default 1.5

• Dynamic_potential_h: h (direction impact) (Defining the Dynamic Potential for a static pedestrian route)

With this parameter you can define the influence of speed on the estimated travel time of a cell. Default 1.5

• If parameter value is 0, there is no influence.
• Parameter value of 1.0 means that the influence of a pedestrian with a typical desired speed can either double, when he goes in the opposite direction, or can drop to zero, when he is heading towards the destination.

• Dynamic_potential_direction_change_clipping: Limit direction change (Selecting network settings for pedestrian behavior)

Use this parameter to determine whether the angle between the fastest and the shortest route can increase at any speed, i.e. whether it can increase randomly from one time step to the next.

• Default value of 1 specifies the allowable degree of deviation with the parameter Direction change angle Dynamic_potential_ direction_change_p.
• If parameter value is 0, no test is made.

• Dynamic_potential_direction_change_p: Direction change angle (Selecting network settings for pedestrian behavior)

With this parameter you can define the maximum permitted angle, by which the angle between the quickest and the shortest path can increase from one time step to the next. If a larger deviation results for a position from the dynamic potential, the direction of the quickest path is determined from the direction of the quickest path from the last turn plus this angle. Default 4 degrees

This parameter value is only considered if for Dynamic_potential_direction_change_clipping (Limit direction change), you have entered the value 1.