Chiang Mai, TH; Ubon Ratchathani, TH; Hanoi, VN
MARS models of these three South East Asian cites were set up during the EU-funded project SPARKLE. The innovation here - besides the new model environment VENSIM - is the so called MARS FS, the MARS Flight Simulator, an application for easier access and use of the model.
The MARS model was intentionally designed to be a "white box" model, but as every model, over time it became more and more a "black box" model. The complexity of the MARS model was increased over the last five years significantly so there was a need to make it useable and user-friendly for a certain group of stakeholders, the transport experts working at local authorities. Fortunately, the VENSIM® programming environment includes an extension called VENSIM APPLICATION to develop a graphical user interface for the existing MARS model. This feature was used to implement a user interface that reflects the needs of decision makers and enables them to operate and run the MARS model for their own specific purposes.
In the following sections, this user interface is introduced by going through a typical task a transport planner has to deal with in his daily business.
The MARS FS application is designed to support decision makers to assess case study specific transport and land use strategies. The MARS FS is a simple to use push button interface for the MARS land use transport model. The application uses a set of commands to give users simplified access to the model. To the user, the MARS FS appears as a series of buttons, menus, or a sequence of screens allowing him or her to use and analyze the MARS model in a straightforward and meaningful way.
Decision makers can themselves tryout their policies and see the consequences immediately.
To navigate through MARS FS you have to operate the appropriate buttons, just like in any other Windows® application.
When opening the MARS FS the first screen you see is the area of the case study with its zones. This screen gives you an impression how the underlying city looks like and how it is split up in zones.
The main menu lets you choose
- to review the model structure,
- to simulate the model or to
- request help how to operate the MARS FS.
The Help pages cover the most urgent matters, e.g. how to review the model, how to simulate with different policies and how to use the output pages.
Every graph, table or document window in the application can be exported to the clipboard for further use.
The button "Review Model Structure" leads the user to a section of MARS FS where he can explore the model inherent cause-effect relations. To be able to do so two different ways are offered:
The model is split up into different views, which in turn depict specific thematic issues within the land use transport system. To review the model structure with the MARS FS application, you can go through every single view, and zoom in and out as necessary.
Causes Tree mode
Another way to review the relationships between the model variables is to use the Causes Tree function. Here a tree-type graphical representation is created showing the causes of the chosen model variable. By clicking on a variable name, the causes tree can be expanded until the final cause is reached.
The core of the MARS FS is the simulation set up screen. On this screen, all implemented transport policy instruments are represented with so-called "sliders". For example in the upper left corner, there is a slider headed "slow modes". Here the user has the possibility to test the impacts of a policy favouring the slow modes (pedestrianisation of the city centre zones). To set up a scenario the user can either pick up the slider with the mouse and moves it to the desired numerical value or keys in a target value in the box below the slider.
This has to be done for a start year (in this case for the year 5 of the simulation as shown with the number on the right hand side of the slider) and for an end year (in the shown example year 20 of the simulation). After the entered end year, the level of the instrument stays constant for the rest of the simulation period. Of course, it is also possible for the user to vary the values for the start and the end years between 0 and 30.
There are different policies for each mode implemented within the MARS model and can be simulated using the MARS FS:
If you think of implementing pedestrian zones or bicycle lanes; you can input how much of the zone will be pedestrianized. This will also lengthen the distance to or from the parking place.
Decrease or increase bus speeds, bus fares or the bus frequency.
Change the fees for motorcycle parking and change taxes and costs for the purchase of a motorcycle.
Charge cars and motorcycles if they enter the cordon, change taxes and costs of a car purchase, offer cars more or less infrastructure, which has influence on the speed, change the fees for car parking and change the prices for fuel.
As soon as the desired policy levers are set, the simulation of the model can be invoked by pressing the "SIMULATE" button.
After the simulation (which takes about 20 seconds on a standard PC), the user can immediately switch between different output variables and formats. Within the existing MARS FS, the following variables are shown in graphs for a "do-nothing" scenario and the user defined "do-something" scenario:
- Mode share in peak and off peak
- Population, workplaces
- Total vehicle km motorized
- Average commuting distance motorized and non motorized
- Total CO2 emissions for car and motorcycle
- Average commuting speed per mode.
The simultaneous display of the "do-nothing" scenario and the "do-something" scenario shows the user the impacts of his tested policy instrument in a clear way.
Analyzing graphs is a good way to get the overall picture, you can see immediately if, for example CO2, increases or decreases. For the ones interested in absolute numbers, there is also option to present for every graph an according table.
If the MARS FS user wants to go into even more detail of analyses, there is the possibility to choose from a list any variable within the model and display it as graph or as a table. This feature also enables the user to display and export information for a certain range of zones, for specific modes, or for specific trip purposes, etc.
After simulation, MARS FS can be set up to export the values for a set of predefined variables in formats like dbase. These data can then be used in a GIS application to produce coloured maps or short movies to make it even simpler for decision makers to analyse the results.
You can download here two different versions of the MARS Hanoi model: as a Vensim published model (*.vpm) or as a Vensim published application (*.vpa). To be able to view and run the models you need to install the freely available Vensim Model Reader at your computer. Important: you need version 5.5 or higher!
to any folder you like. The only important thing is that the two Excel data files are in a sub-folder "Data" and that the bitmap files are in a sub-folder "Pics". To run the normal MARS model open the file "CaseStudy_Hanoi.vpm" using the Vensim Model Reader software. To run the flight simulator version of MARS open the file "CaseStudy_Hanoi.vpa" with using the Vensim Model Reader software.