Traffic Count Data in the Regional Transportation Data Clearinghouse

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Traffic Count Data in theRegional Transportation
Data Clearinghouse

• Martha Kile and Yew Yuan
• TPB Travel Forecasting Subcommittee
• January 18, 2008

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Previous Clearinghouse Versions

• Prior to 2001 printed reports were used to
  populate volumes
• Volume recorded on several links
• Only included AADT
• May 2001 hourly/directional volumes
• Distributed as ArcView 3.2 project
• Traffic Volume file contained all years and link
  descriptive information

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New Clearinghouse

• Volumes since 2001 are populated only for the
  link on which the volume was taken
• Used digital files indicating counting station
  location
• Matched each count station to the corresponding
  Clearinghouse link
• Used both spatial and attribute analysis
• Identified links that should be treated
  differently
• Multiple stations assigned to one link
• Parallel facilities

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New Clearinghouse (continued)

• Included both AADT and AAWDT where available
  starting in 2005
• Count Type indicates source and vintage of count
• ArcGIS
• Several Tables
• Descriptive information and traffic volumes are
  stored separately
• Smoothing and Averaging for maps not in the main
  data file
• Estimated volumes not carried in data file
• Eliminates confusion of which volumes to use

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Sources of AADT/AAWDT

• Maryland
• 2001-2004 Maryland SHA AADT by station
  identifier
• 2005 and 2006 AADT and AAWDT by station
  identifier
• Virginia
• 2001-2006 VDOT (Richmond) AADT and AAWDT by
  station identifier
• Arlington County DPW (from Website) AADT
  2001-2004
• DC
• AADT from DC HPMS Submission 2001-2006
• West Virginia (Jefferson County)
• AADT from Jefferson County Traffic Volume Map
  2002 and 2005

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How AADT/AAWDT is assigned to a link

• Each station location is assigned to a link
• XY location and location description
• Links that have a one-to-one relationship with a
  station
• Link is assigned the AADT and AAWDT of the
  station
• CT code indicates the vintage of the counts
• Links that are assigned multiple stations
• Most recent AADT and AAWDT
• Mean of the most recent AADT and AAWDT

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Map Showing Station-link Assignment
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Sources of Detailed Volumes

• Hourly Directional Volumes (at standard counting
  locations) 2001-2006
• MD SHA
• VDOT
• DDOT (2004-2005)
• Supplemental Counts where available
• Short Term and Turning Movement
• VDOT Northern Virginia
• MD SHA
• Montgomery County
• DDOT

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ArcGIS Application

• Current GIS Software
• Relational Database
• Estimated volumes used for mapping are not
  carried in the data files. Eliminating confusion
  of which volumes to use
• Menu for Traffic Volume Queries
• By Route
• By Year
• By Project-ID

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Traffic Volume Queries
- Year - Count Type
- Route ID - Project ID - Year
- AADT/AAWDT - Detailed Counts
Month Day of Week
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(No Transcript)
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Query Returns Traffic Volume Table
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Conclusions

• Goals
• Make traffic volume data
• More accessible
• More accurate
• More meaningful
• Sources for Additional Traffic Counts?
• Need for Additional Functionality?