3.3.7.2 Determine Growth Rate

The growth rate is a critical component needed to forecast traffic volumes. It can be determined using various methods. All methods listed in this section can be used to determine growth rate. The growth rate may vary from method to method, so it is recommended that multiple methods be checked for validation purposes. If needed, work with the District, TPP, and DES to develop interim growth rates. Three methods of determining growth rate are as follows:
  • Historical traffic growth data
    • Analyze traffic volumes over time at a particular location. Obtaining historical traffic volumes is discussed in
      Chapter 2
      .
    • Use of the linear regression spreadsheet provided in
      Appendix D, Section 4 – Regression Calculations
       is suggested to calculate historical traffic growth rates.
  • Population growth data
    • Analyze population growth from multiple years to determine the traffic volume growth rate over time. Population data can be found in the US Census data or in the state demographer forecasts.