Introduction to VISSIM

INTRODUCTION TO VISSIM AVINASH UNNIKRISHNAN, WEST VIRGINIA UNIVERSITY

INTRODUCTION The objective of this tutorial is to train students into using VISSIM to simulate a basic traffic corridor without any control devices such as signals. The tutorial has the following sections;      

User Interface Overview Basic Features of VISSIM Simulating the First Model Creating your First VISSIM Network Generating Vehicle Inputs Generating Output Files

The creating your first VISSIM Network and Generating Vehicle Inputs have been based out of the Brian Hassett’s online tutorial. VISSIM is a microscopic traffic simulation model created by PTV (Planung Transport Verkehr) based out of Germany. VISSIM stands for Verkehr In Städten – SIMulationsmodell. VISSIM uses a microscopic traffic simulator for moving traffic. VISSIM is widely used for traffic control and operations analysis.

VISSIM USER INTERFACE OVERVIEW An overview of the VISSIM is given below VISSIM Version Number and Network Name

Menus For File Management

Toolbars for File Management, Network Editing, Simulation Control, etc.

For help press F1

VISSIM BASIC FEATURES As a first step let us try to open an example network file. Go to the folder MyDocuments/Manual Example. RBC/ and open RBC_Example_Free.inp. Note that in VISSIM, the network files have an .inp extension. You should get the following window.

Show Entire Network

Link Number and Position

You can zoom and zoom out by left clicking the magnifying glass button and selecting the necessary area. Right clicking anywhere on the screen will take you back to the original setting. Another way is to left click the show entire network button.

Left Click VIEW and then Select Options. You will be able to change the global display options in this window. You essentially use this window to change the visual settings.

Click on Center Line. Press OK. Now see how the display changes. Now go back and change it to Normal. You can also change the language and the units.

If you change any specific settings, you can then save the settings by clicking VIEW, Save Settings and then giving a file name. The setting files have a .ini extension. Hover your mouse around the toolbars on the left and understand the signal settings. Click on View. Make sure that the “Show Network Elements” box is checked. Left click on Signal Head and Detectors. Observe the changes in the network.

Signal Head Detectors

Another way to view the network elements is to click on View and then Network Elements and then check the box under Show Element and press OK.

SIMULATING THE FIRST MODEL Click on Simulation. Then click on parameters. You should get a window like this.

The period field contains information on how long you want the traffic to be simulated. For example if you are interested in simulating traffic for only 10 minutes then you will enter 600 seconds. The start time is the starting time of the simulation. For example if your simulation corresponds to traffic from 7:30 to 7:40 then you enter the start time as 7:30:00. You can also adjust the simulation speed. By increasing the simulation speed, you can complete the simulation faster. However visualizing the congestion will be difficult at high speeds. Another thing you want to do is click on View, then Status Bar and make sure that the time option in checked.

Click on Simulation/Parameters and change the starting time to 7:30. Now press Simulation and then click on Continuous.

Change the simulation speed to 16 and then press OK and then run the simulation again. You will find that the vehicles are moving faster. This is the equivalent of watching a movie at 2X.

CREATING YOUR FIRST VISSIM NETWORK Go to File, Click on New. Then click on Save as and enter the Name of the file. I am naming this as FirstExample. Left click on Links and Connectors.

Left click here

Right click in the main area, drag and then release. The arrow direction corresponds to the direction of traffic. You should get a link data screen as shown below. Now adjust the parameters of the link data.

Enter the following parameters: Number of lanes 3, Behavior type: 3: Freeway Press OK. You can now left click and drag and increase the length of the link. Try to get it near 500 ft. Right click the middle of the link, you create a node. Then you can drag the nodes to create a bend. Create three nodes, drag the nodes upwards and then bend the road.

Now create two more roads as shown in the figure. Let the upper road have one lane and the lower road have two lanes.

One Lane

Two Lanes

Now we need to create the connectors between the two links. Left click on links and connectors. Right click on the original link and drag the arrow till it meets the link with two lanes. Now release the mouse. You should get a window like this.

This contains the attributes of the connector link. You can see two boxes for from link and to link with lane 1 and lane 2 highlighted. This means that vehicles from lane 1 and 2 from the original link can move to the lane 1 and lane 2 of the new link. Lanes are always numbered from the inside. Press OK.

Now repeat the same for the top link. You should get a window like this. Make sure that lane 3 is connected to lane 1.

If you specified your connectors correctly you should get the following window.

VEHICLE INPUTS Go to the toolbar on the left, Select Vehicle Inputs by left click.

Left Click

Left click on the first link and select the link. Right click near the beginning of the link to get the vehicle input dialog box.

Enter the rate at which the vehicles enter the system as 1000 veh/hour. Select the vehicle distribution type to be default.

Rate at which vehicles enter

Default Distribution

Press OK. Then choose Simulation and click on continuous and you should see the cars moving. Change the simulation period to 600 seconds. So we will be simulating for a period of 10 minutes in all future simulations. We now see that vehicles are generated at the rate of 1000 veh/hour and then they are randomly assigned to top and bottom roads. Let us say we want to assign a percentage on the number of vehicles which choose a top road and the number of vehicles which choose a bottom road. We do that by first choose routes on the toolbar on the left.

Left click here

Follow the following steps carefully: Left click on routes. Left click and select the from link. Right click on a point on the from link. Choose the point carefully. The point where you right click will correspond to the routing decision point – point where drivers make decisions.

Look at the location. The field next to link is 1 which indicates that this is at link 1 and the routing decision is at 281.123 feet from the beginning of the link.

Press OK. Now left click the connector and right click towards the end of the connector. Your screen should resemble this.

Now left click on the top connector and right click on a point towards the end. Your screen should look like this.

Now right click on any point on the screen other than the network. You should get a routing dialog box. This indicates that in this network drivers need to make one decision at a distance of 284.929 feet from the start of the network.

The decision to be made is should they choose route 1 or should they choose route 2. Route 1 is to choose the bottom link and route 2 is to choose the top link. Let us focus on the column highlighted in the box. It has number 1 for route 1 and number 1 for route 2. The relative magnitudes of the numbers indicate the percentage of vehicles choosing route 1 and route 2. The above numbers indicate that 50% of the vehicles choose route 1 and 50 % choose route 2. Press Ok. If you press simulate and press continuous and watch the simulation you will observe that half of the vehicles choose route 1 and half of the vehicles choose route 2.

I am going to change that. I want 70% of the vehicles to choose route 1 and 30% of the vehicles to choose route 2. I will change the numbers to 70 and 30.

Press Ok. If you press simulate and press continuous and watch the simulation you will observe that more vehicles are choosing the bottom route than top route.

OUTPUT FILES Collecting Travel Time Information In order to collect the travel time information left click on the alarm clock button on the left side of the toolbar.

Click here for Travel Time

In order to collect the travel time information we need to define the section for which we are collecting travel time information. Left click on the link which contains the starting point on the travel time section and right click on the starting point of the travel time section. You should see a red band.

Red band

Now select the link which contains the end of the travel time section by left click and right click the end point on that link. For this case let us pick the lower link. You should see a green band and a travel time measurement window as shown below.

Green Band

Repeat the same procedure to create one more travel time measurement section, this time from starting link to top link.

Press Ok.

Right clicking on any point on the screen other than the network will provide the travel time section measurement information.

There are two ways to visualize the VISSIM Travel Time output – online manner where you can see the travel time changes as the simulation runs and in an outputfile format.

Online Manner: Select Evaluation/Windows/Travel Time.

You should get a window like this:

Now press Simulation / Continuous and watch the travel times change with simulation.

Output Files: Go to Evaluation/Files. Check Travel Times in the resulting window as shown below and Press OK.

Click on Configuration next to Travel Times and enter the time information for collection of travel time data for both sections.

This means we want travel time information from 0 to 600 seconds at intervals of 30 seconds

This signifies we are collecting travel time data for both sections 1 and 2

Press OK multiple times and run the simulation.

We want compiled processed data and not raw date

Data Collection Points In VISSIM it is also possible to “collect” speed, volume information at specific points on the freeway. To do that first select data collection points from the left toolbar.

Data Collection Points

Left click a link to select the link and then right click on a point on the link to select the location to install a data collection point and Press Ok.

Data Collection defined only at lane level and not at section level. If there are three lanes you will need three data collection points if you want the section level data.

Go to Evaluations/Files and Check Data Collection.

Click on Configuration right next to Data Collection and choose compiled or raw data.

Choose from Compiled or Raw Data

Click on New.

Click on New

Select the Measurement Point and Press OK.

Enter the time information for compiling the data. In this case we are collecting data from 0 to 600 seconds at intervals of 30 seconds.

Data Collection Interval Information

Click on Configuration

Once you click on configuration, you will get the following window.

Select all parameters you want the information on. I am going to select Mean Speed and Number of Vehicles.

Selected Mean Speed and Number of Vehicles

Now press OK multiple times run the simulation.

Analyzing the Outputs The name of the network file is FirstExample.inp. The data collection information will be in a file called FirstExample.mes which will be located in the same folder as FirstExample.inp. The travel time information will be in a file called FirstExample.rsz which will be located in the same folder as FirstExample.inp. You can open both files using Excel by following the same instructions. I will show the instructions for FirstExample.mes. Open Excel. Select File Open. Make sure you change File type to include All Files.

Change to All Files

Go to the directory and Open FirstExample.mes. You should get the Text Import Wizard.

Make sure delimited and not Fixed Width is Selected

Press Next. In the Delimiters List make sure only semi colon is checked.

Only semicolon should be checked

Press Next and then Finish.

You should get the following output file which contains the data collection information.

By repeating the same process for Travel Time Information you should get the following