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Traffic Count Data in the Regional Transportation Data Clearinghouse. Martha Kile and Yew Yuan TPB Travel Forecasting Subcommittee January 18, 2008. Previous Clearinghouse Versions. Prior to 2001 printed reports were used to populate volumes Volume recorded on several links
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Traffic Count Data in theRegional Transportation Data Clearinghouse Martha Kile and Yew Yuan TPB Travel Forecasting Subcommittee January 18, 2008
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
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
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
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
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
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
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
Traffic Volume Queries - Year - Count Type - Route ID - Project ID - Year - AADT/AAWDT - Detailed Counts Month Day of Week
Conclusions • Goals • Make traffic volume data • More accessible • More accurate • More meaningful • Sources for Additional Traffic Counts? • Need for Additional Functionality?