2007 ITE District 6 Annual Meeting July 17, 2007 Sirisha Kothuri Kristin Tufte Robert L. Bertini PSU...
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Transcript of 2007 ITE District 6 Annual Meeting July 17, 2007 Sirisha Kothuri Kristin Tufte Robert L. Bertini PSU...
2007 ITE District 6 Annual Meeting July 17, 2007
Sirisha KothuriKristin TufteRobert L. BertiniPSU
Hau HagedornOTREC
Dean DeeterAthey Creek Consultants
Survey of Best Practices in Real Time Travel Time Estimation and Prediction
2007 ITE District 6 Annual Meeting July 17, 2007
Outline
• Real Time Estimates
• Data Collection Approaches
• Current Travel Time Practices
• Case Studies
• Summary
• Lessons Learned
2007 ITE District 6 Annual Meeting July 17, 2007
Real-Time Travel Time Estimates
• FHWA policy– Errors up to 20% acceptable
• Dissemination– Websites – Dynamic Message Signs (DMS)– Cell Phones & PDA’s– In Vehicle Navigation– Radio Broadcasts
2007 ITE District 6 Annual Meeting July 17, 2007
• Fixed Detection of Volume & Occupancy– High cost approach – Inductive Loops or Radar Sensors
Data Collection Approaches
Inductive Loop Detector
2007 ITE District 6 Annual Meeting July 17, 2007
• Fixed Detection of Speed– Low cost approach– Allows calculation of travel times easily– Lacks traffic counting capability
2007 ITE District 6 Annual Meeting July 17, 2007
• Direct Detection of Travel Times– Toll Infrastructure– Accuracy is high
Toll Plaza
Source: bata.mtc.ca.gov/tolls/fastrak.html
Toll Tag
Source: http://fastrak.sandag.org/images/ftrans.jpg
2007 ITE District 6 Annual Meeting July 17, 2007
• Data Fusion Approach– Private Vendors
• Traffic.com• Inrix
– Fusion of data • Fixed Sensors
– Loops
• Mobile Sensors– Fleets– Cell phones
Source: www.traffic.com
2007 ITE District 6 Annual Meeting July 17, 2007
Current Travel Time Practices
Alaska
Hawaii
PuertoRico
D.C.
= Provide Travel Times (25)
= Plans to Provide Travel Times (17)
September 15, 2006
2007 ITE District 6 Annual Meeting July 17, 2007
Portland, Oregon•Data Collection
•~ 500 Dual Loop Detectors
•Speed, count, occupancy every 20 seconds
•Travel Time Estimation•Travel times from speeds & segment lengths
•Midpoint Algorithm with ODOT influence areas for each detector
•Currently reported only on 3 DMS
Loop Detector
Locations
Travel Times on
DMS
2007 ITE District 6 Annual Meeting July 17, 2007
Seattle, Washington•Data Collection
•Single Loop Detectors
•Record Occupancy, Volume
•Travel Time Estimation•Speeds from occupancy
•Travel times from segment lengths & speeds
•Includes historical travel times
•Reported on DMS & web
•Accuracy > 90%
2007 ITE District 6 Annual Meeting July 17, 2007
Minneapolis – St. Paul, Minnesota•Data Collection
•Single Loop Detectors
•Record Occupancy, Volume
•Travel Time Estimation•Speeds from occupancy
•Travel times from segment lengths & speeds
•Modified Midpoint Algorithm
•Reported on DMS & web
•Generally accurate except in transition conditions
2007 ITE District 6 Annual Meeting July 17, 2007
Chicago, IL
Data Collection•Tolled Facilities
•Toll tag readers & RTMS
Travel Time Estimation•Algorithm – Toll Tag + RTMS
•Posted on DMS & Web
Data Collection•Non -Tolled Facilities
•Loop Detectors (Occ & Vol)
Travel Time Estimation•Speeds from Occ, travel times from speeds and segment lengths
2007 ITE District 6 Annual Meeting July 17, 2007
San Francisco, Bay Area•Data Collection
•Loop Detectors
•AVI Toll Tag Readers
•Spot Speed Sensors
•Travel Time Estimation•Algorithm fuses data from three sources
•Estimation done by private vendor
•Dissemination through DMS, web and 511 system
2007 ITE District 6 Annual Meeting July 17, 2007
Atlanta, Georgia•Data Collection•Video Detection System Cameras
•Record speed & volume
•Travel Time Estimation•Travel times calculated from average speeds
•Travel times estimated separately for main line and HOV lanes
•Dissemination through DMS, web
2007 ITE District 6 Annual Meeting July 17, 2007
Summary
• Common approaches for speed/travel times– Loop detectors
• Minnesota, Portland, Seattle, Wisconsin• Proven technology• Detector spacing is important
– AVI Toll Tags• Houston, Illinois, San Francisco, Houston• Number & spacing of tags influences accuracy• Considered reliable
2007 ITE District 6 Annual Meeting July 17, 2007
– Speed Info Sensors• North Carolina, San Francisco• Use Doppler technology to measure speed• Reliability during adverse weather conditions is
of concern
– Private Approaches• Illinois• Fuse data from different sources• Offers potential with limited in field new
deployment of systems
2007 ITE District 6 Annual Meeting July 17, 2007
• Travel Time Calculations– Agency developed – In house
• Seattle, Portland, Twin cities - MN• Midpoint Algorithm commonly used• State agencies are responsible for estimation
and dissemination
– Contractor developed• Illinois Tollway, Bay Area• Benefit derived from contractor experiences in
multiple states• Maintenance and updating of proprietary
algorithm performed by contractor• Estimation and dissemination of information
either by agency or contractor
2007 ITE District 6 Annual Meeting July 17, 2007
Lessons Learned
• Decision factors for travel time calculations– Travel Time reporting needs
– Ownership and responsibility of data collection, equipment & algorithms
– Data collection and calculation approach
• Other Considerations– Cost
– Reliability & accuracy
– Ease of use
2007 ITE District 6 Annual Meeting July 17, 2007
Acknowledgements• Mark Hallenback
• Galen McGill