The primary objectives of this phase are: (1) to establish the purpose and need, (2) to develop a range of potential alternatives that meet the purpose and need, and (3) to conduct a screening-level assessment to eliminate alternatives that are clearly not feasible or inferior.

This phase is intended to further define and evaluate the alternatives advanced from Phase A. This includes the development of conceptual design plans and the evaluation of each alternative under consideration. Alternatives with major flaws or disproportionate negative impacts will be eliminated from further consideration. The second step includes additional engineering refinements for the remaining alternatives to more precisely define the project footprint, right-of-way needs, costs, and development schedule.

Preliminary design defines the general project location and design concepts. It includes, but is not limited to preliminary engineering and other activities and analysis.