Statewide Traffic Factor Analysis

North Carolina (Statewide)

VHB is managing a program for North Carolina Department of Transportation (NCDOT) to generate Peak Average Daily Traffic (PADT) Factors to understand seasonal traffic variation for all 100 counties in North Carolina. The program involves developing a sampling plan for each county to count, interpolate, or extrapolate the counts to develop the PADT Factor, coordinating with data collection vendors and the NCDOT Traffic Mobility & Safety Group, statistical analysis, GIS analysis, and process automation.

When stay-at-home orders and travel restrictions resulted from COVID-19, traffic across the nation came to a halt and presented challenges to collecting traffic data necessary to move projects forward. VHB began pilot testing Intersect to generate PADT Factors.

With the Intersect methodology, VHB developed a model to generate PADT factors using probe data for NCDOT’s continuous count station locations to develop comparison analysis. VHB is now working on the next Phase of this project using probe to generate PADT factors for locations in 25 counties for which PADT Factors were generated in 2019 using traditional methods. This data will be used for calculating Volume to Capacity (V/C) ratios, which will prioritize projects for funding.

Intersect opens the opportunity for NCDOT to continue this program post-pandemic. Because Intersect reprocesses counts from data at any time and is not impacted due to weather related delays or school closings, instead of using one week or season’s worth of measurements for calculating the PADT Factor, our team can calculate a month’s worth of data per season.

The return on investment using probe data has been proven to be higher compared to traditional data collection methodology, especially when used at a statewide level, saving the client potentially millions of dollars. Additionally, the use of Intersect gave the VHB team greater accuracy, helping the client make better decisions based on stronger data. Because of these added benefits, the VHB team continues to generate PADT Factors for the remaining counties through Intersect.

Cars moving through intersection. Map on screen of iPad. Map on screen of Computer.


  • North Carolina Department of Transportation


  • Application Development

  • Intersection Design & Engineering

  • Traffic Simulation Modeling

  • Transportation Planning & Engineering