Implementation of Travel Time in the CHART ATMS

1. Implementation of Travel Time in the CHART ATMS ITS America Annual Conference May 3, 2010 Scott Dalrymple

2. Agenda • Overview of Travel Time Architecture • INRIX Data Import • Travel Routes • Message Templates • Traveler Information Messages • Lessons Learned

3. CHART Travel Time Architecture

4. Traveler Information MessageOperational Concept

5. Traveler Information MessagesOperational Concept (Cont.) • CHART Travel Route holds travel time and/or toll rate data for use in CHART • INRIX supplies travel time data • Vector supplies toll rate data • Traveler info templates defined by administrator • Templates combined with travel route data to create DMS message

6. INRIX Data ImportINRIX Link Definition Import • INRIX Link definitions imported into CHART DB via offline utility • INRIX link definitions included in CHART to ease association of INRIX links to CHART Travel Routes • Updates to INRIX link definitions an infrequent administrative procedure • Update required if new links added to INRIX that are desired for use in CHART • Links are rarely removed, so updates have minimal impact on existing CHART Travel Route configuration

7. INRIX Data ImportINRIX Travel Time Data • CHART Periodically Polls INRIX for travel time data • Includes travel time, speed, quality, & confidence value per link • Uses existing INRIX HTTP / XML interface • Current poll rate is 2 minutes • Importer passes link travel time data to Travel Route Service • Alerts / Notifications can be configured for import problems • Connectivity to INRIX lost • Corrupted or unexpected data / format • Missing required link data • Travel Route Service updates travel times for each INRIX link associated with a CHART travel route • Raw data from INRIX used by CHART stored in archive DB

8. Travel RoutesAdministration and Operational Use • Administrators create and manage routes • Add/Edit • Combine INRIX links to define contiguous travel route • Partial links supported by percentage parameter • Associate Vector toll route with travel route • Set other configuration data • Configuration changes will be archived • Remove (warn if known to be used) • Operators can view current data • Sort / Filter • Travel Time Trend • Recent Travel Time / Toll Rate History

9. Travel RoutesCalculation • Travel time for a route is computed based on the travel time data from its associated links • Travel times from individual links are summed • Links partially included contribute the specified percentage of their travel time • Sum is constrained to configured minimum travel time • Travel time greater than the speed limit is never displayed • Route travel time voided out if too many links below configured quality • Route travel time voided out if it exceeds a maximum configured value • Alert or notification can be sent if travel time exceeds an alert threshold

10. Travel RoutesDisplay and Archive • Travel routes, travel times, toll rates are displayed on GUI • Independent of display on DMSs • Travel times and associated data are archived • Historical analysis / Operational review • 40 routes estimated 4 GB/year including reason/calculation • 40 routes estimated at 20 MB/year for just the final number

11. Travel Routes - Travel Route List

12. Travel RoutesTravel Route Details

13. Message TemplatesAdministration and Operational Use • Administrator can manage templates • Add/Edit • Specify layout of message • Specify which travel route data should be included, and where • Specify format used for data from travel routes • Specify other miscellaneous settings • Remove (warn if known to be used) • Templates target a specific DMS size • Administrator specifies how to react to missing data • Discard entire message • Discard page with missing data • Discard row with missing data

14. Message TemplatesData Formats • Data formats (travel time, travel time range, toll rate, toll rate effective time, distance) defined in database • Configurable via database administrative function • Anticipate very few (if any) changes to available formats • Data formats selected in GUI are copied into template • Makes templates resistant to future changes in data formats • Prevents change to format from changing field width, making message no longer fit on sign

15. Message TemplatesTravel Time and Toll Rate Message Template List

16. Message TemplatesMessage Template Editor

17. Traveler Information MessagesAdministration and Operational Use • Administrator creates traveler info messages • Selects template • Selects travel route(s) • Operator enables / disables traveler information messages on DMS • User can enable only 1 traveler info message at a time per DMS • System constrains display on DMSs to configured hours of operation • Alerts /Notifications can be configured for DMS failure conditions • Particularly important for toll rate display

18. Traveler Information MessagesAdministration and Operational Use • DMS object registers for updates to routes used in its traveler info messages • DMS object builds final message using template and travel route data • Existing “Arbitration Queue” mechanism used • Message(s) at top of queue are sent to DMS for display • At Toll Rate priority if message has a toll rate in it • At Travel Time priority if message has no toll rate • Priorities used can be overridden per DMS • Message combination rules extended to include the new message classes • User can manually reprioritize messages on queue

19. Traveler Information MessagesDMS List

20. Traveler InformationMessagesDMS Details

21. Traveler Information MessagesAdditional Travel Route Configuration Parameters • Travel Routes associated with DMS • Allows for short list of travel routes when setting the travel route(s) to appear in message • Travel Time Display Schedule • System-wide schedule that can be overridden per DMS • Travel Time Ranges • System-wide setting to determine how an actual travel time (e.g. 17 mins) is changed into a range (e.g. 15-19 mins)

22. Traveler Info Message DesignVector Import • CHART provides HTTP / XML web service where Vector connects and periodically supplies data (approx 3-10 mins) • Public/Private key authentication used to verify data is from Vector system and not corrupted • Importer passes toll rate data from Vector to Travel Route Factory • Travel Route Factory updates toll rate data for each Vector toll route associated to a CHART travel route • Toll Rate Data used by CHART archived in DB • 90 days of data for 20 toll routes will take 5.2 MB of disk space • Travel route pushes data to DMSs • Primary / Backup configuration used for fault tolerance • Vector always attempts to use primary first • Primary service issues alert if not contacted within configurable time • Backup service issues alert when used (indicates problem with primary) • Alerts / Notifications

23. Lessons Learned • Built-in flexibility supports changing MDSHA requirements • Important to validate initial Travel Route definition and calculated travel times against “ground truth” from probe vehicles • INRIX data produced odd results during snow storm • Quality Indicator level 20 in use • Free flow/normal speeds indicated on roads where traffic was at standstill • Free flow/normal speeds indicated on nearly impassable roads • Results normalized when only level 30 data was used • INRIX is reticent about explaining data anomalies • Public education campaign could have been better • Complaints travel time messages are slowing traffic covered by local media • Complaints received that the travel times are static

24. Questions

25. Larry Schreider CSC Director, State and Local Solutions 410-691-6664 lschreid@csc.com Linda Hanger CSC CHART Program Manager 410-694-5594 lhanger@csc.com Scott Dalrymple CSC CHART Program Software Architect 410-691-6638 sdalrymp@csc.com Darrell Shahin CSC CHART Program Systems Engineer 410-691-6714 dshahin@csc.com Contacts