1. Traffic Count Data in the Regional Transportation Data Clearinghouse Martha Kile and Yew Yuan TPB Travel Forecasting Subcommittee January 18, 2008

2. 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

3. 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

4. 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

5. 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

6. 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

7. Map Showing Station-link Assignment

8. 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

9. 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

10. Traffic Volume Queries - Route ID - Project ID - Year - AADT/AAWDT - Detailed Counts - Year - Count Type Month Day of Week

12. Query Returns Traffic Volume Table

13. Conclusions ► Goals  Make traffic volume data ► More accessible ► More accurate ► More meaningful ► Sources for Additional Traffic Counts? ► Need for Additional Functionality?