6 FUTURE YEAR FORECASTING

6 FUTURE YEAR FORECASTING

6.1 Purpose

Design Hour Volumes (DHV) are used for ODOT planning and project level analyses. These are based on the existing year volumes developed in Chapter 5. The DHV is generally defined as the future year 30th highest hour (30 HV). Depending on scope and complexity of the analysis, different future methodologies are needed from simple historical trends to complex travel demand models. This chapter will outline the procedures for developing DHV and future Average Daily Traffic (ADT) used for ODOT planning and project level analysis. In addition, the processes for developing pavement design traffic volumes are also discussed. Future design hour volumes are a key input in following analysis steps and methodologies explored in later chapters. For more details on many of the methods in this chapter also refer to NCHRP Report 765.

6.2 General Considerations

The DHV typically controls the design of the project or represents a planning horizon year such as in a Transportation System Plan (TSP). These volumes can either be for nobuild or build conditions.

6.2.1 Rounding

The DHV's need to be rounded before the network is balanced. The traffic volumes are not that precise to go down to one vehicle, especially considering projections that may be out 20 plus years. Balancing the network is easier if the network is not down to the individual vehicle. Future years five or ten years out should be rounded to the nearest five vehicles. Twenty-year future volumes can either be rounded to the nearest five or ten vehicles. Volumes less than five vehicles should use the " ................
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