Webinar 8
Missouri DOT’s (MoDOT) Traveler Information Map

January 19, 2011

Summary of the Federal Highway Administration’s Quarterly Webinar: Applications of Geospatial Technologies in Transportation

These notes provide a summary of the PowerPoint presentation discussed during the webinar and detail the question and answer session that followed the presentation.

The presentation is available upon request from the webinar speakers, Matt Hiebert and Stuart Harlan (Charles.Hiebert@modot.mo.gov and Stuart.Harlan@modot.mo.gov).


Matt Hiebert
Web Manager
Missouri Department of Transportation (MoDOT)

Stuart Harlan
Senior Information Systems Technologist


Approximately 35 participants attended the webinar.

Introduction to Presentation

Mark Sarmiento of the Federal Highway Administration (FHWA) thanked participants for joining the webinar. This webinar was the eighth in a quarterly series of FHWA-sponsored. The series deals with the application of geospatial information systems (GIS) and other geospatial technologies to transportation. This webinar focused on the development of MoDOT's Traveler Information Map.


In 2003, as part of a revamp of its public website, MoDOT created a Traveler Information Map to convey weather-related road conditions to the public to supplement news reports. This static map used a JPEG format and was refreshed every five minutes with updated conditions. It did not accommodate zooming and initially only offered conditions on major routes, alongside a separate map that depicted active work zones.

From feedback on these initial maps, MoDOT learned that the public wanted more information. In its first update to the system, MoDOT decided to provide a basemap through Google Maps, which not only offered more information, but also eased the strain on MoDOT's servers. Additionally, while the first iteration of the map was static, the Google basemap allowed users to pan and zoom. The public reacted favorably to this new version but there were some downsides. First, Google did not update its maps as frequently as MoDOT would have liked. The new version of the map also performed slowly on certain browsers, particularly the version of Internet Explorer that MoDOT was using at the time. Finally, a flood in the spring of 2007 highlighted a serious flaw in the Google basemap: Google mistook a rush of traffic to the site as a hacker attack and subsequently shut down the service.

Based on these experiences, MoDOT began researching other technologies that would provide a better user experience and narrowed the choices to JavaScript, Adobe Flex, and Microsoft Silverlight, each of which supported MoDOT's ESRI GIS. MoDOT decided to use Adobe Flex, finding JavaScript prone to bugs and limited support at the time for Silverlight.

Traveler Information Map Architecture
The current version of MoDOT's Traveler Information Map (available at http://traveler.modot.org/map/index.html) operates using ArcGIS Server 9.3.1 with a .NET implementation and an Adobe Flex 3 API. It stores information in an Oracle relational database. MoDOT runs queries every five minutes to load data from the Oracle database into XML files, a robust procedure that allows the map to serve more data than it could with a traditional ArcGIS Server setup.

MoDOT plots traffic conditions on a cached basemap, which is processed within MoDOT and re-cached every one to two months, depending on the availability of updated data. The map can also display weather radar images pulled from the National Weather Service's website.

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Mr. Hiebert and Mr. Harlan briefly demonstrated the features of MoDOT's Traveler Information Map. The map is prominently featured in JPEG format on MoDOT's homepage next to a link to the interactive version. The interactive version provides users with access to multiple layers, including roadway incidents, flooding, work zones, and winter weather. The map also offers images from traffic cameras and messages displayed on variable message signs along Interstate routes. Users can pan and zoom the map down to the street level and can export map views to PDF files to print. Finally, MoDOT maintains a text-report version of the map that lists all road closures, work zones, and flooding incidents.

Outcomes and Lessons Learned
The current version of MoDOT's Traveler Information Map has been running since September 2010 and is in use by the public on all major internet browsers, with Internet Explorer the most prevalent. Over 90 percent of map users access it on a computer running Windows but the site also experiences some visitation from mobile users with smart phones running Android or Apple iOS operating systems. Currently, mobile users can only access the static map but MoDOT is considering an interactive mobile version for future iterations.

Recently, MoDOT was able to evaluate the performance of the system under the demanding circumstances of a snowstorm in January. The interactive and static maps respectively received 76,900 and 192,000 visits on the day of the storm and experienced peak traffic of 3,900 and 6,800 visits per hour.

Through their experience developing and updating MoDOT's Traveler Information Map, Mr. Hiebert and Mr. Harlan have documented several lessons learned:

  • Load test using real visitor traffic scenario. It is important to test various scenarios that represent how actual users will interact with the site to identify weak points or limitations.
  • Balance the importance of interactive versus non-interactive components. Load on the interactive map fell significantly when MoDOT began using a static image of the map as the entry point to the interactive page. If some users can extract sufficient information from the static image, the load on the interactive site might fall so more bandwidth is available.
  • Assess which features are necessary and which are extraneous. Mr. Hiebert and Mr. Harlan originally wanted to have the system depict information in real time, but doing so would have required significantly more computing power and funding.
  • Learn from colleagues who manage high-volume websites. Based on the expertise of staff who manage other high-volume MoDOT websites, Mr. Hiebert and Mr. Harlan were able to test the Traveler Information Map with realistic loads to determine how the site would behave and identify possible weaknesses.

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Question and Answer Session

How do data enter the Oracle database?
MoDOT has a GIS-based system that combines a Flex map and ASP pages. When a road crew calls to report that they cleared a particular section of road, a MoDOT employee will enter the data into Oracle using the mapping and ASP interface. When the map refreshes (every five minutes), the new data transfers to an XML file and then into the map. The frequency of update depends on the event. Data for work zones are entered as they are planned and traffic incidents are entered as soon as MoDOT knows about them.

What is the source of your winter road condition data?
It comes directly from road crews. Plow drivers are assigned a certain segment of road to plow and when the conditions change on that segment, they call the MoDOT customer service department or data entry section. Updated information appears on the map within minutes of MoDOT staff entering it.

Do you incorporate a global positioning system (GPS) on your plow trucks to display the information on the map?
Not at this time. We are looking ahead and it is possible that future iterations of the map will be tied to real-time data. Currently there is about a five minute delay between when a driver calls MoDOT with updated information and when the information appears on the map.

Are you planning to add the locations of plow trucks to the map?
That is a good idea but we have not discussed it.

Did you look into using the .NET Silverlight API?
Yes, during the planning stage. At that time, we compared Flex and Silverlight and decided that Flex would better suit our needs. Silverlight has made some improvements since then. Since ESRI supports both, we could consider it again in the next iteration.

How long does it take to regenerate your cached tiles?
Our current setup uses one 8-core machine for caching, which takes 1.5 to 2 hours.

Have you had any accessibility issues with Flex?
We address Section 508 compliance by supplying a text list of road conditions and closures that can be read by electronic screen readers. It is difficult to make an actual map accessible to screen readers. We have had one complaint out of 100,000 users regarding use of a Flash-based program. That is another reason why we display a JPEG map image of road conditions.

Is the cache located in the Server Object Container (SOC) or in remote storage?
In the current setup, tiles are located on the same machine as the SOC. One machine can handle all components because the cache is relatively small. We are planning a distributed setup for a new ArcGIS server; in that case, the cache will be located on a separate machine that can accommodate larger caches.

Have you considered or is there demand for exposing spatial data as a GeoRSS feed?
We have only received one request for a GeoRSS feed. We have considered it but are not planning to pursue the idea. If we receive more requests, we might consider accommodating them.

How often are traffic camera images updated?
Cameras are updated every five minutes or less. The map can display snapshots from 62 cameras and we are planning to add more. Some are updated several times per second to simulate streaming.

Does the user have a choice of base layers (e.g., hill shade, roads, satellite images)?
Since this is MoDOT's first foray into hosting cache maps, we began with the road layer as the minimum necessary information. MoDOT has a source of statewide aerial images, which are cached internally. We will consider including them in the map when the new GIS server architecture is in place, as images occupy much more disk space.

Do you use tabular information to update travel incidents or are the extents actually mapped?
Anything that goes into MoDOT's data management system must be located on one of the State's travel ways. MoDOT has a system for registering an incident that includes a highway identifier and a location along that highway. Location information is stored in the Oracle database and referenced to GIS line layers, which can be converted into geographic coordinates.

Are conditions for work zones or crashes linked to the Scout system (a traveler information system for Kansas City)?
Scout and the MoDOT Traveler Information System are managed separately, although MoDOT is currently in the middle of a task to consolidate its system and similar systems for Kansas City and St. Louis into one database.

Does the XML technique allow you to simplify your roadway geometry?
The roadway condition lines constitute the only geometry information provided via XML; all other data are point data. MoDOT currently uses an algorithm in its Oracle database to simplify the data. In the future, MoDOT plans to increase the number of travel ways on which it can display road conditions. This involves simplifying the condition lines so that when users zoom in, they see sufficient detail but not so much detail as to clog the system with data.

Is commercial advertising possible on the state website?
We have looked into commercial advertising. There is currently no policy against advertising on the State website but we are still researching whether there are reasons not to allow it. For instance, if we begin to introduce advertising, it would bring up a question of whether we have to screen all of the advertisements that are posted on the website.

Do you have a map server that MoDOT uses internally that contains more detailed information? Is there something that management uses as a dashboard to quickly find information?
There is currently no dedicated application for MoDOT employees to use internally. MoDOT employees who can add information to the system can access more detailed information about road closures and road conditions but there has not been much interest in an organization-wide internal application. For a long time, MoDOT maintained a nearly identical map that displayed the variable message signs but then added those signs to the Traveler Information Map at the request of the Missouri Highway Patrol.

How much usability testing did you do prior to the release?
We maintain a list of every complaint that MoDOT has ever received about the map. We store that information and ask users to participate in beta testing and previews of new features. Some of our best ideas have come from the public, so we test any significant upgrades with a group of about 50 people.

We did not do much usability testing when we converted the system to Flex, because the interface was largely based on the Google Map interface that we had been using.

Why did you choose to have the content display on the right side of the map instead of using a Google-style pop-up window?
It was a design decision. We had the technical ability to use pop-ups but decided instead to use the right-hand display.

Do you also use Twitter and other social networking tools to release updates on road conditions and closures?
MoDOT headquarters will announce road closures or conditions on a major Interstate through Twitter and Facebook. Otherwise, it is up to the district offices how they announce these events. Some MoDOT district offices use Twitter and Facebook but they are responsible for their own accounts.

Did you have issues with funding the development and maintenance?
No, we created the whole system in-house. Some of MoDOT's consultants provided advice but they did not contribute any programming hours to the system. Providing that advice was part of their existing contract so it did not add cost to the development.

Does MoDOT offer a 511 phone system?
There is not a statewide 511 system but there is a 511 system for St. Louis.

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