Traffic Data Computation Method Pocket Guide

Traffic Data Pocket Guide

This report by the US Department of Transportation’s Federal Highway Administration provides succinct computational methods for selected traffic data items. The audience for this publication is anyone involved in the collection, processing, analysis, utilization, and reporting of traffic data.

The following forty-eight traffic data items are covered in this guide.

  1. 85th Percentile Speed
  2. Annual Average Daily Traffic (AADT)
  3. Annual Average Daily Truck Traffic (AADTT)
  4. Average Daily Traffic (ADT)
  5. Axle Correction Factor (ACF)
  6. Capacity
  7. Change Rate
  8. Combination Unit Truck AADT
  9. Critical Speed
  10. Design Hour
  11. Design Vehicles
  12. Design Volume
  13. Directional Design-Hour Volume (DDHV)
  14. Directional Factor
  15. Directional Flow Rate and Ratio
  16. Equivalent Single Axle Load (ESAL)
  17. Free Flow
  18. Future AADT
  19. Gross Vehicle Weight (GVW)
  20. Headway
  21. K-Factor
  22. Lane Groups
  23. Load Spectra
  24. Month of Year and Day of Week Factors
  25. Monthly Average Daily Traffic (MADT)
  26. Number of Intersections of Other Type
  27. Number of Signalized Intersections
  28. Number of Stop Sign Intersections
  29. Passenger Car Equivalent (PCE)
  30. Peak Hour Factor (PHF)
  31. Percent Green Time
  32. Percent Peak Combination Unit Trucks
  33. Percent Peak Single Unit Trucks & Buses
  34. Roadway Occupancy
  35. Saturation Flow
  36. Saturation Headway
  37. Short Term Count ADT by Vehicle Class to AADT by Vehicle Class Conversion
  38. Short Term Count ADT to AADT Conversion
  39. Signal Type
  40. Single Unit Truck & Bus AADT
  41. Time of Day (TOD) Factor
  42. Traffic Demand
  43. Turning Radius
  44. Vehicle Class Factoring
  45. Vehicle Density
  46. Vehicle Miles Traveled (VMT)
  47. Vehicle Speed
  48. Volume and Volume-to-Capacity Ratio

Each item includes a brief description, followed by “discussion and illustration” that explains how the data item is used. For most data items, supplemental notes and tips useful for computation are provided.  Cross references are provided for further insight.

Click here to download this 116 page report.