Quarterly Report Highlights
Transportation System Modeling and Evacuation Planning
Multi-Dimensional Data Visualization in TransimsVIS
| The focus of development on this application this quarter was primarily on the addition of new features, packaging with TransimsStudio, and distributing to key user groups. The features developed were driven largely from the needs of outside users, including CMAP.
One of the efforts has been to overhaul the 2D models used in TransimsVIS. Real world models were used to sketch custom overhead designs for trucks, buses, and trains. Buses were modeled after the CTA buses used in Chicagoland and the trains were modeled after the Metra trains used by Chicago commuters. The primary challenge comes from translating the essence of a vehicle with as few pixels as possible by exaggerating certain features. Below, are the images for each of the new models.
The vehicles pictured here are the raw vehicles at a fixed scale, big and small. During any simulation, the scale at which these vehicles are displayed can be even smaller than the example shown of the Small fleet. The different elements of each vehicle, Front, Mid, and Back, allow TransimsVIS to accommodate different size vehicles. The modules are combined based upon rules within TransimsVIS to determine what vehicle type, load, and passenger capacity.
| Another focus was on simplifying how a project should be defined. An important feature added in this category was a "Save Configuration" option. When the user develops certain styles such as car colors, heat plots, import layers, etc ... they can now save the current state of the visualizer, this file can be reloaded at any time to bring up the state of the visualizer as it had been upon the last save. In addition, the previous file used to control which files were read in was refined to use keys which would be more recognizable to the broader TRANSIMS community.
One of the primary points of visualization is to be able compare different case scenarios to one another. Multiple ideas were explored for the best way to do this including: using two frames internally, superimposing the data somehow, or using two separate windows. In the end, the dual monitor idea won out due to the simplicity of execution and customizability given to the user for each case. There were two options which were to start the copy as a new process or within the existing process. The advantage of the latter was that data could more easily be shared between the two copies, however the glaring disadvantage was that it would further tax the single core which TransimsVIS had to run on (wx python has no truly effective options to utilize multiple processors). Therefore, the current method spawns a copy as a child process of the first. It is able to pass simple information through standard input/output. The two are currently able to be linked in navigation; that is, when navigation occurs on the parent process, the child process will follow within a couple of seconds. Users have requested that there be an additional synchronization in time as well as space, so this is likely going to become a future feature.
|The probe vehicle feature has been very popular with outside users, so it has been enhanced in a couple of ways. First, users are interested in seeing specific probe vehicles - for example to look at all the vehicles originating from a certain traffic analysis zone. Therefore, the capability was added to input a file which contained a list of vehicle ids, these will become the only probes visualized. A portion of these can still be selected by percentage. In addition, users were interested in seeing the movements of only certain types of vehicles such as heavy trucks. A pull down list was added which contains all of the legal vehicle types users can select among them to determine what probes to show.|
|One extremely important feature of GIS software is the ability to identify network elements such as roads and intersections. This helps a user to be able to understand how the underlying data tables are visualized. The most commonly required identifications are nodes and links, so an option was added which would allow the user to identify either of these elements on screen (while still maintaining the ability to identify vehicles).|
|This phase of development entailed many small improvements to improve the user's experience and also to troubleshoot compatibility issues across multiple types of TRANSIMS cases. Some menu items have been shifted around, certain features have become more easy to use such as selecting and deleting multiple layers/facility types, and simple conveniences such as allowing the user to set an automatic stop time for movies have been added. The file interpreter is now much more flexible to allow reading in of link, node, and vehicle type files which are in every format that TRANSIMS itself allows. In addition, many small bugs such as interpolation not working correctly for some values have been corrected.|
|A fairly major addition to the capability of TransimsVIS to create cinematic movies is the waypoints feature. The user can essentially bookmark positions in time and space which can be returned to at a later time. This feature can be extended to save a series of waypoints at 1 minute intervals and follow a path between each of them as the simulation plays or records frames. This has the potential to create one movie which can present multiple traffic situations.|
|A feature which has been requested by multiple users is the ability to customize the car coloring schemes in TransimsVIS. To accommodate this need, 3 interactive menus now allow you to customize colors and categories. For the speed coloring, users can define speed ranges into categories and which colors for each of those speeds. For vehicle type coloring, users can match vehicle types with colors. Finally for passengers, users can match passenger ranges with colors. Changing passenger colors now also changes the color of the ridership circles.|
|A feature currently in development is a second visualization paradigm for signals. The original "regional" visualization is great for determining how well synchronized a corridor or grid of signals is. However, when it comes to determining what is going on at an individual intersection, it doesn't provide enough information. Therefore, the "local" signal visualization has three main goals: show all relevant protected phases for an intersection, give the user a sense for how far into the phase they are, and integrate fully with the system event table to account for dynamic actuated signal behavior. The biggest challenge in this development was determining how to automatically shape the arrows so that every movement could be visualized properly for any intersection.|
| One of the major advancements in making TransimsVIS more usable is an effort related to begin integrating it with TRANSIMS Studio. First, the Alexandria case which comes with TRANSIMS Studio has been expanded to include a script file which will run through the ArcSnapshot and compression steps necessary to produce a TransimsVIS compressed snapshot. Also included is a TransimsVIS control file which is usable with the program upon completion of the Alexandria case study run. Next, TransimsVIS source can now be found on Source Forge within the TRANSIMS Studio project. Next, TransimsVIS has been made part of the TRANSIMS Studio installer —it is still a separate executable and an independent program, however it gets installed when TRANSIMS Studio is installed. Finally, dozens of tiny installation-related changes were made so that it would run, be able to spawn copies, create output, and read files on any computer after being installed.
Distribution and giving support to the user community has also been a priority this quarter. The program has been distributed to and is being used by: TRACC, Dr. Jun S. Oh at the University of Western Michigan, AECOM consulting's TRANSIMS group, CMAP (Chicago Metropolitan Agency for Planning), Illinois Institute of Technology, Brian Grady at Resource Systems Group, and Georgia Regional Transportation Authority (GRTA). Working with these organizations to troubleshoot problems and add new features has been very successful in slowly but surely producing a more industrial product which is useful to the TRANSIMS community.
TransimsVIS has found immediate application by TRACC in the analysis of the Elgin-Ohare expressway extension project. The project entails studying the congestion effects of adding a new highway segment. The majority of this study involved examining various router stabilization routines to obtain a higher performance routing and making network modifications to fix and resolve particularly bad intersections. This project, however, is the first example of the usefulness of the TransimsVIS in analyzing TRANSIMS cases. The heat plot, in particular proved to be extremely useful to quickly determine where the congestion "hot spots" were from a regional perspective. Performing this study was the impetus to develop such features as the "identify link" and "identify node." Below is an example of a comparison frame between two case studies.