This section of the Transportation Conformity Reference Guide provides information on general requirements for making a transportation conformity determination. Beyond the requirements noted in Chapters 1-5, readers should review Chapters 6-14, as appropriate, to their nonattainment or maintenance area. Readers should refer to the Navigation Tool in Part II to facilitate understanding of which chapters will be of interest. The information on general transportation conformity requirements is presented as shown below:
These requirements create the foundation for the conformity determination and address planning and analytical requirements as well as institutional coordination issues. The transportation plan and TIP requirements are set forth in ISTEA, SAFETEA-LU, and FHWA and FTA's planning regulations. This planning process supports and reinforces the transportation conformity rule and is required in all metropolitan nonattainment and maintenance areas. The transportation plan and TIP are discussed in Chapter 1.
Interagency consultation is discussed in Chapter 2 and is the central coordinating mechanism for public agency involvement and input to the conformity determination. All nonattainment and maintenance areas are required to comply with these transportation conformity rule provisions.
Transportation Control Measures (TCMs) are discussed in Chapter 3. TCMs are strategies committed to in a State Implementation Plan (SIP) to help reduce motor vehicle emissions caused by transportation sources by reducing vehicle use or changing traffic flow or congestion conditions. Transportation Control Measures (TCMs) are not required; however, they are an option. In addition, these strategies are often of interest to MPOs and are measures transportation agencies can use in order to reduce emissions from transportation sources.
Chapter 4 explains conformity lapses and their impact on transportation plans, programs, and projects. Conformity lapse issues are important for the reader's understanding of the consequences of not having a conforming transportation plan and TIP. This chapter also includes a discussion on conformity freezes and the associated impacts on transportation plans, programs and projects.
The regional emissions analysis is the central test upon which conformity determinations are based. This requirement includes both travel demand and emissions modeling and an estimate of the regional emissions levels, which would be present in a region at specific junctures during and after the implementation of the transportation plan and program. The analysis must use the latest planning assumptions and latest emissions models. Chapter 5 explains the general regional analysis requirements. Specific requirements for different types of nonattainment and maintenance areas and project level analysis are explained in Chapters 6-14.