Approaches to Forecasting Third Performance Management Rulemaking (PM3) Measures for Target Setting

Summary

This document offered a step-by-step calculation guide for three forecasting methods in support of target setting for the travel time-based performance measures.

The three forecasting methods covered in this document were:

• Extrapolation of past trends (macroscopic). This approach requires multiple years of empirical travel time data. Additional multiyear data on VMT and other influencing factors are highly recommended.
• Highway segments “at risk” for unreliability (microscopic; based on identifying segments that close to the reliability threshold). This approach requires only a single year of travel time data.
• Model-based forecasting. This approach works in conjunction with a travel demand model and does not require travel time data, other to establish current conditions and developing relationships to predict the percentiles of the travel time distribution. Additional data on hourly distribution of traffic are also needed.