Tiered environmental studies in the national environmental policy act process for highway projects

In recent years, there has been a renewed interest in the use of tiering and tiering-like procedures as techniques for managing the National Environmental Policy Act (NEPA) process for highway projects. However, experience with these procedures remains limited, and guidance materials are scarce. Thus, available information is brought together about tiering, the benefits and drawbacks of tiering are assessed, and general advice is offered about when to use tiering and what issues to consider in a tiered NEPA process. The effort consists of five parts. First is an introduction of NEPA and its processes, followed by information on regulatory authority and guidance, early experiences with tiering, recent developments in tiering, benefits and drawbacks of tiering, and issues to consider in preparing a tiered study.