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Map Help

Help Overview | Map Help | Reports Help | MyTravel Help

The GCM Travel site includes interactive map pages that present traffic information graphically. The maps are generated dynamically and display up-to-date traffic conditions in the form of colored areas and icons. The maps provide a way for you to quickly get a picture of the current traffic conditions in various parts of the site's coverage area. The maps are not updated automatically, but you can update the information presented by refreshing the page in your browser.

The maps are accessed via the "Maps" menu header in the menu bar. Selecting "My Map" displays a map that stores the map configuration in a cookie on your browser so you can use to get a map of your preference quickly. Selecting the "Chicago Area", "City of Chicago", "Gary", "Madison", "Milwaukee", "Rockford", "Quad Cities", or "SW Michigan" menu item displays a map initially centered on that location.

The maps can be scrolled and zoomed to allow you to view the area in which you are interested, at the desired level of detail. The magnifying glass controls (4 in the figure below) allow you to zoom in and out. To scroll the map, press the mouse within the map image and drag the image in any direction. When you release the mouse button, the map will be redrawn at the position to which you moved it, filling in the areas that were left empty when you dragged the image. Depending on various factors, it may take a few seconds for the map to reload. The map will not scroll beyond the coverage area, so it may not scroll the full amount when the edge is encountered.

Information on the maps is displayed in layers, e.g. there are layers for message signs, cameras, and road labels and shields. Layers may be displayed or hidden to allow you to focus on the information you find useful, and to remove information you do not find relevant. Initially, all the layers are displayed.

As you scroll and zoom a map and turn layers on and off, the location, zoom and layer information is stored in a cookie on your browser. In this way, you can refresh the map to update the real-time information without losing track of the area and the types of information you were viewing. The cookie for the "My Map" page is maintained for three months so that your preferred map configuration will be ready to use when you return to the site. If you have disabled cookies for your browser, then you will not be able to use this feature.

Because of the size and complexity of the maps, the time it takes to generate them and send them from the GCM Travel site server to your browser may be noticeable. Please have patience as the maps load. When using the map controls, please wait for the effect of a click to be displayed before clicking again.

Once you have selected a map, you will see a page much like the one below (this image is the Chicago map).

The main sections of the map page are:

  1. Map Navigator - The Map Navigator displays an overview map of the selected region. Clicking on the Map Navigator redisplays the main map centered at the position of the click on the Map Navigator.
  2. Map Legend - The Map Legend describes the icons and congestion color coding used on the Main Map.
  3. Main Map - The Main Map displays roadways and information about the currently selected layers, at the current zoom level and scroll position.

The controls for the map area and appearance are:

  1. Zoom Controls - The magnifying glass controls below the arrows cause the Main Map display to zoom in (+) or out (-).
  2. Layer Controls - The nine toggle buttons at the top right of the map control which layers are displayed on the Main Map. Clicking on a button will hide or show that map layer. If the button appears pushed in, that layer is visible. If you hover your mouse over the control (without clicking), a tool tip will appear that indicates which layer the button affects and whether that layer is currently visible. In order from left to right, the buttons affect the following layers: Construction, Road Labels, Congestion, Incidents, Travel Times, Airports, Message Signs, Cameras, and Special Events.

The symbols that indicate events, traffic conditions and devices are:

  1. Incident - This icon indicates that there has been an incident reported at this location, which is believed to still be currently affecting traffic conditions at that point. The effect will vary from incident to incident. Clicking on an incident icon opens a small window displaying information about that incident.
  2. Section Construction - The jagged orange lines along a roadway indicate that there is construction or maintenance activity on the indicated section of that roadway. In some cases, indicated by a darker orange, this activity might be moving along the section indicated, so that the entire section is not affected at a given time. In other cases, indicated by the lighter orange, the whole section is most likely affected. Clicking on the section construction icon opens a small window displaying information about the selected construction.
  3. Point Construction - The traffic cone icon indicates a construction or maintenance activity at the location indicated by the icon. In the case of point construction, the activity is occuring in a small area and not along any long length of roadway. Clicking on a point construction cone opens a small window displaying information about the selected construction.
  4. Congestion - The coloring of the major roadways indicates the detected congestion of that roadway, based on the speed of vehicles on the roadway. The colors range from dark green (uncongested) to red (heavy congestion), as indicated on the Map Legend. Only roadways which are equipped with detection equipment are colored in this way. If a roadway has such equipment, but the GCM Travel site is unable to determine the current congestion (e.g., due to a communication error), the roadway is colored gray. Roadways which have no detection equipment do not display congestion colorization. Clicking on a colored congestion segment opens a small window displaying the location, congestion level and last update time.
  5. Travel Time - The white teardrop and black circular icons with numeric labels display up-to-date travel times. In the Chicago area, the teardrop icons display the travel time to and from the Chicago downtown area to the location of the icon, with the point of the teardrop indicating the direction of travel. The black circular icons indicate the travel time on a roadway section. Clicking on a travel time icon opens a small window containing more information, e.g. the endpoints for a circular travel time icon.
  6. Message Sign - This icon marks the location of a dynamic message sign. Clicking on a message sign icon opens a small window displaying the sign's location, status, message and the time the site last received a notification from the sign.
  7. Camera - This icon marks the location of a camera. Clicking on a camera icon opens a small window displaying the latest image the site received from the camera together with reference views so that you can determine which direction the camera is pointed. In some cases, especially when the map is zoomed out, it is not possible to show an icon for each camera because there are several very close together at that zoom level so a single icon represents a group of cameras. When this happens, clicking on such an icon presents a report with a row for each camera that gives the camera location and a thumbnail of its latest image. Clicking on one of the thumbnails displays the window containing the latest image and the reference views.
  8. Special Event - This icon indicates that there is a planned event at that location which may affect traffic conditions. Clicking on a special event icon opens a small window displaying information about that event.
  9. Road Labels - The numerical designations of major roads are shown using the customary shield icons. Road names are also displayed, depending on the zoom level. Clicking on a road opens a small window displaying the road name, number of lanes and speed limit, if available.
  10. Airport - This icon indicates an airport. Clicking on an airport icon opens a window displaying the home page of that airport (if any).
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Thu Mar 11 12:53:28 CST 2010