Transportation Systems Simulation - A Tutorial for Multi-Modal Simulation Using VISSIM/Pedestrian: Geometric Network Design
Geometric Network Design
This section introduces an interactive example project that builds a multimodal pedestrian simulation using areas, obstacles, static routing, and vehicle interactions within a mixed-use shopping area. The base Vissim file with the vehicle network and the base data excel file can be downloaded here. The network building tutorial explains step by step how to build the pedestrian network, set up base data, and evaluate the model.
The purpose of the simulation is to model the routes of a group of pedestrians who park in the southwest parking lot at a shopping center and travel through the shopping area. It can be assumed that the data for the pedestrian input and routes are based from traffic studies. This data includes 5 minute interval flows in persons per hour and static pedestrian routes. The static pedestrian routes model the stores the pedestrian visit at the mall before returning to the parking lot.
The figure below shows the complete example network with the background image showing. The model consists of 8 small stores, 4 medium stores, and one large store. The pedestrians that leave the origin area will travel to the large store, a medium store, and a small store, then return to the same area and leave the model. For this example there are 53 routes, each with a different large, medium, and small store combination. Again, this is assumed to be correspond to data collected in the field. It should be noted that this is not a complete simulation of the entire mall, which would require all parking lots to have a pedestrian origin and routing decisions and much more sophisticated routing.
The base model file is called theshoppesbase.inpx. Download this file along with theshoppesbase.layx and theshoppesbase.inp0. This file contains links, connectors, vehicle, vehicle routes, stop signs, speed decisions, and parking. These should not be modified during the pedestrian network building. The pedestrian network will be built around this vehicle network and interact at crosswalks. The figure below shows the base network.
Place Sidewalk Areas
The file shoppesdata.xlsx contains the vehicle input data along with the pedestrian base data, input data, and routing data that will be inputted during this exercise. This pedestrian data will be used along with the pedestrian network construction to define the pedestrian simulation. Now that the base file is ready, the pedestrian areas, crosswalk links, ramps, and obstacles need to be set up. The figure below shows the location of the sidewalk and doorway areas. The small boxes are doorways adjacent to where a store area will be placed. Be sure the doorways are wide enough to accommodate flow in both directions. The z-offset and thickness for the sidewalk will be 0.67’ because that is the curb height.
- Left Click on the network object Areas (Polygon) (see Figure below).
- Then hold Ctrl and Right Click on the area to place a point for the area.
- Refer to the figure below for the Area locations outlined in red dashed lines. (see Figure below).
- To place the last point for a single area, Double Left Click and the dialog box will open with the area attributes.
- For all the sidewalk areas enter “sidewalk” in the Name: box. Keep the level as “1: Base”.
- Insert “0.67” into Z-offset and Thickness (3d). This will be useful when visualizing the 8” curb in 3D.
- Leave all other values default.
- Click OK.
- Repeat this procedure for each area separately as shown in the Sidewalk Areas Figure. There are a total of 24 areas.
TIP: Use the background image and the sidewalk area figure to assist in locating where to put the 24 sidewalk areas.
Set Time Distributions for Store Areas
- Go to Base Data > Distributions > Time to show the Time Distributions tab (see Figure below).
- Then Right Click in the Time Distributions pane and go to Add.. > Normal Distribution.
- Insert 3 new time distributions with the data shown in the figure below and in shoppesdata.xlsx. This is assumed to be based on the data collected on the duration pedestrians spent in different size stores.
Place Store Areas
- Left Click to highlight the network object Areas (Polygon) (see Figure below).
- Then CTRL + Right Click on the area to place the first point. Follow this procedure for every corner of the area.
- To place the last point, Double Left Click and the dialog box shown in the figure below will open with the area attributes.
- For all the store areas enter “large store”, “medium store”, or “small store” in the Name: box.
- Keep the level as “1: Base”. Insert “1.00” into Z-offset and Thickness (3d).
- In the Time Distribution drop down list, choose the either storessmall, storesmed, or storeslarge depending on the store size.
- Leave all other options default.
- Click OK.
- Repeat this procedure for the 13 stores shown below outlined in red dashed lines.
TIP: Try to match the sizes of the stores to the above figure, but they do not have to be exact. Only the large store corresponds to the background map.
- Left Click to highlight the network object Links (see Figure below).
- Then CTRL + Right Click on the area to place the link start point.
- Double Left Click to place the link end point and open the link attributes.
- For all the crosswalk areas enter “crosswalk” in the Name: box. Keep the level as “1: Base”.
- Check On the box Use as pedestrian area. Insert the width that best matches the background image under Width.
- Right Click on the display tab and Insert “0.1” into Z-offset and “1.00” into Thickness (3d).
- Choose “Ped area red” as the display type.
- Leave all other values default.
- Click OK.
HINT: The z-offset is 0.100' in order to show above the roadway links in 3D view, but without showing a step.
- Repeat this procedure for the 10 crosswalks shown below outlined in red dashed lines.
Model Conflict Areas
- Click on the Conflict Areas network object (see Figure below). This will highlight all conflict areas in yellow.
- Hover the mouse over conflict areas that need rules defined.
- Right click on areas that need to be set and choose Set Status to Undetermined for ped-vehicle conflicts.
- Repeat this procedure for all ped-vehicle conflicts. This will give priority to whoever arrived first.
- Click on the Ramps & Stairs network object to highlight it (see Figure below),
- Right Click a corner where the ramp starting point is to be placed. The next point placed defines the opposite starting point corner. Now the width is locked in and the next point placed defines the end of the ramp.
- Add each of the 18 ramps shown in the second figure below. The ramps are outlined in a red dashed line.
- For each, enter “curb ramp” in the Name: text box, “0.67” in the Z-offset(start) box and “0.1” in the Z-offset(end) box. Enter “0.67” in the thickness box.
- Leave all other values as default and
- Click OK.
HINT: The Z-offset(start) and Z-offset(end) box correspond to the z-offsets of the sidewalk areas and crosswalk links respectively.
WARNING: Pay close attention to the location of the start and end elevations. View the model in 3D to verify the elevations are flush to the sidewalk and crosswalk links.
- Click on the Obstacles network object to highlight it (see Figure below).
- Right Click where placement is desired using the polygon method place a point at each corners, or using the rectangle method place the two corners for the starting point and width and set the end point.
- Follow the approximate layout of the figure below.
- Enter “planter” in the Name: text box, “1.0” in the Z-Offset text box, and “2.0” in the height text box.
- Click OK.
- Repeat this procedure for all 13 planters shown below outlined in a dashed-yellow line.