Traffic Volume Data Collection

1. Traffic Volume Data Collection Daniel Jenkins, PE Substitute – Steven Jessberger Office of Highway Policy Information October 23, 2012

2. Why Collect Volume Data? • Planning/Environment • Project Development • Operations • OHPI needs it • MAP-21

3. Planning/Environment Needs • Air quality analysis • Noise studies • Traffic projections

4. Project Development Needs • Interchange Justification Reports • Design • Maintenance of Traffic Decisions

5. Operations needs • Traffic signal timing • HOV operations • Work zone decisions

6. OHPI Needs • HPMS • Monthly TVT report • Temporal Traffic Studies

7. TVT Report • Data Requirements • ATR data submitted to TMAS by the 20th of the month after the close of the month • TMAS software performs a number of quality checks on data • 7 day error • 7 zero hour error • Adjacent hour error • Directional split error • MADT check same month year to year • Maximum volume per hour per lane (new in 2012)

8. Report available at http://www.fhwa.dot.gov/ohim/tvtw/tvtpage.cfm

10. Who wants TVT? • Automotive industry companies • Insurance companies • Financial services • Retail

11. MAP-21 • National freight policy • Designate National freight network (AADTT) • HSIP • Traffic data defined as safety data Crash rates based on VMT • Performance measures • Congestion reduction • System reliability

12. QUALITY DATA

13. Guidance • AASHTO Guidelines for traffic data programs • Traffic Monitoring Guide (TMG) • HPMS field Manual

14. Types of Sensors • In road/on road • Loops • Piezos (axle sensors) • Tubes

15. Types of Sensors- cont. • Off road • Infrared • Magnetic • Radar • Microwave • Acoustic • Video

16. Factors • Monthly Factors • Day of Week Factors • Axle Correction Factors • Yearly Growth/Reduction Factors Determining an accurate AADT is very important to a successful program!

17. Factors Example - Seasonal

18. Factors Example – DOW

19. Factors • Misusing the DOW factor can lead to a 5% underestimate • Misusing the Monthly factor can lead to a 15% overestimate • Do you factor and are you following the TMG or some other method?

20. Problem • The DOT did a traffic count on a minor rural collector (Site A) between January 26-28 (Tuesday-Thursday). The total count for three days was 3,600 vehicles. Calculate the AADT for Site A.

21. Solving Problem • Locate an ATR on a similar class facility

22. Solving Problem • Locate an ATR on a similar class facility • Found a ATR on a rural minor collector in the adjacent county with the following characteristics: • 290,800 veh./yr. • January traffic- 19,800 veh.

23. Solving Problem • Locate an ATR on a similar class facility • Found a ATR on a rural minor collector in the adjacent county with the following characteristics: • 290,800 veh./yr. • January traffic- 19,800 veh. • Calculate AADT and MADT for the ATR site • AADT=290,800/365= 797, say 800 vpd • MADT= 19,800/31= 640 vpd

24. Solving Problem • Locate an ATR on a similar class facility • Found a ATR on a rural minor collector in the adjacent county with the following characteristics: • 290,800 veh./yr. • January traffic- 19,800 veh. • Calculate AADT and MADT for the ATR site • AADT=290,800/365= 797, say 800 vpd • MADT= 19,800/31= 640 vpd • Compute monthly correction factor • AADT/MADT = 800/640 = 1.25

25. Solving Problem • Determine AADT for Site A

26. Solving Problem • Determine AADT for Site A • Calculate ADT for site A • ADT= 3,600/3= 1,200 vpd

27. Solving Problem • Calculate AADT for Site A • Calculate ADT for site A • ADT= 3,600/3= 1,200 vpd • Calculate AADT • AADT= 1,200 X 1.25= 1,500 vpd DOW factor would also need to be applied

28. Data- Collect once, correctly and use many times

29. QUESTIONS????????????? Danny Jenkins, PE Volume Program Manager 202-366-1067 daniel.jenkins@dot.gov