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Today's Presentation. Data Collection PurposeMethodsPros and ConsExamplesData UsabilityDetermining Factors for Method SelectionData ExpansionLessons Learned. Data Collection Purpose. External Station or Corridor Origin/Destination Surveys are conducted to determine the number and characteri
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2. Today’s Presentation Data Collection Purpose
Methods
Pros and Cons
Examples
Data Usability
Determining Factors for Method Selection
Data Expansion
Lessons Learned
3. Data Collection Purpose External Station or Corridor Origin/Destination Surveys are conducted to determine the number and characteristic of the trips traveling through a study area (or along a corridor)
Usually collected to provide better inputs to the travel demand model
External – External (EE) trips are unique to an area
Conducted around the periphery of a study area or at various locations along a corridor
4. Methods Intercept
Interviews
Postcard Handout / Mail Back
Video License Plate Capture
Matching
Mail Out / Mail Back
Follow up call
5. Methods – Intercept Interviews Used mainly on lower volume facilities (<20K ADT)
Use along high volume facilities:
At/near ramps or tolls sites
Weigh station – commercial vehicles
Rest areas
Effective for toll feasibility, user/attitudinal studies
Electronic collection
Tablet PC
Handheld device
Paper collection
Traffic control necessary
6. Methods – Intercept Interviews
7. Methods – Intercept Interviews
8. Methods – Intercept Postcards Postcards are handed out and mailed back
Used mainly on lower volume facilities (<20K ADT) for stand alone external station collection
Traffic control necessary
Used along higher volume facilities at alternate locations
Rest areas
Convenience stores/gas stations
Visitor Centers
Effectively used at intersection locations
Minimal traffic control necessary
Signal timing a consideration
9. Methods – Intercept Postcards
10. Methods – VLP Capture Passive data collection method
Effective for use on high volume sites
Video camcorders or digital cameras used depending on lighting conditions
Rear license plate captured
Cameras placed on shoulders or overpass
Data elements include: license, state, vehicle classification, time, direction
Plate matching for through trips
DMV matching for follow up survey or home location
11. Methods – VLP Matching Plates captured at all locations on same day
Plates transcribed (92-95% from OCR and manual)
50% good transcription with OCR
30% with OCR & manual correction
12-15% manual transcription
2-3% obscured
2-3% missing (daylight conditions)
State and vehicle class entered
manually
Matching results in site to site
occurrence matrix
EE trip % by site
12. Methods – VLP Capture
13. Methods – VLP Capture Follow Up Plates captured at all locations on same day or on different days
Plates transcribed usually with OCR only
Match with DMV records for follow up
Call interview
Mail out/mail back postcard
Call interview can be anonymous or not
Mail out survey can ask questions much like postcard handout
14. Methods – VLP Capture Follow Up
15. Methods – VLP Capture Setup
16. Methods – VLP Capture Setup
17. Methods – VLP Capture Examples
18. Methods – VLP Capture Examples 2005 Baton Rouge – 3 VLP, 9 postcard*
2005 DFW – 9 VLP, 38 interviews, 18 comm. interview
2005 San Antonio (1604) – 3 VLP, 10 postcard
2005 Washoe County (Reno) – 7 VLP
2007 Baltimore – 9 VLP on 3 corridors
2007 Kansas City – 6 VLP, call follow up
2007 Treasure Valley – 9 VLP, 3 interview (POIs), alt. sites
2008 Delaware (US 301) – 7 VLP
2008 MAG/PAG – 18 VLP
2010 PART, NC – 7 VLP, 13 interviews
2010 Colorado Front Range – 11 VLP, 47 postcard
19. Data Usability
20. Method Selection Facility types (interstate, arterial…)
Roadway cross-section, physical conditions
Policies of DOT and other affected agencies
Volume of traffic (> or < 20k ADT)
Data elements and quality
Costs and resources available
Time of year (lighting)
Sensitivity to potential negative public reaction
21. Data Expansion Data reduction
Develop expanded EE trip tables from VLP
Develop expanded EE/IE trip tables from other data
Aggregate intercept and VLP EE/EI trip tables
Assign proxy EE/EI trip distributions to non-surveyed sites
Develop final EE/EI trip tables
22. Lessons Learned Intercept interview
Best done on low volume facilities (queuing)
Becoming less popular
Intercept postcard
Self selection bias may be acceptable trade off
Best done at intersections and alternate locations
VLP capture
Passive method: no interruption for traveling public
Best done without press involvement
Mail out/mail back survey from VLP
Need quick turn around for mail out
Keep survey form simple
Provide website for participation and toll free contact number
23. Questions
J.D. Allen, AICP
jdallen@emailatg.com
337.310.7020 office
337.802.6655 mobile
www.alliance-transportation.com