The purpose of NCHRP 8-83: Analytical Methods in Traffic Forecasting is to update and replace the well known and universally accepted NCHRP 255 Report which has been in use for traffic forecasting purposes for over 30 years. This report is intended to be used for traffic forecasting in design, planning and operational analysis. The CDM Smith project team will finish this report in June 2013. The Interim Report was issued in March 2012, which:

• gave an overview of work to be updated from the 255 report,

• provided the results of a survey administered to the traffic forecasting community,

• identified the major sources of traffic forecasting information (source documents),

• reviewed tools used for traffic forecasting, including travel demand models, and

• developed a comprehensive roadmap for the final report guidebook.

The new guidebook will include some of the following features. It will:

• contain useful case studies that will be based in most cases on actual travel demand models and/or traffic forecasts;

• update the time of day tables using automatic traffic recorder data from eight states;

• update the existing spreadsheets used for adjusting model data to factored traffic forecasts;

• contain electronic files corresponding to topics that will be available on the web;

• contain new algorithms for traffic forecasting such as origin destination matrix estimation, and;

• give best practice/acceptable practice for key traffic forecasting topics such as speed data (both uncongested and congested), communicating results, checklists for modeling, a selection matrix for the correct traffic forecasting tool to be used, use of 4-step and activity based models in traffic forecasting, guidance on developing/using a multi-resolution (hybrid) model incorporating both travel demand modeling and simulation modeling and many other topics.

We will present lessons learned along the way, the rationale for including/not including certain methods, and some practical tips on how to use the procedures.