Unpacking dimensions of a tiering typology: Delegation, direction and strength

Within environmental assessment (EA), tiering between higher-tier strategic environmental assessment at the plan and program level and lower-tier environmental impact assessment at the project level creates effective communication, ensuring that insights are not isolated to the planning level in which they were derived, but can inform and guide other levels. Tiering can travel in many directions – ensuring that strategic goals make it into implemented projects and that information gained in project levels inform future strategic planning. This research extends the tiering concept along three dimensions, ‘delegation’, ‘direction’ and ‘strength’. It does so to further existing conceptual understandings and gain a nuanced understanding of the role that especially strategic levels have in ensuring meaningful tiering. To illustrate the new conceptual tiering typologies, the research draws upon a case study of three Danish EA reports on spatial planning to understand how tiering is delegated between planning levels. The illustrative case study concludes that a procedurally effective referral of information between planning tiers calls for tiering practice that is explicit and is both delegated and successfully implemented in the appropriate planning levels. Consequently, this paper not only furthers theoretical perspectives; it also demonstrates how the proposed typology can be applied and opens for further reflection on the potentials and limitations of the typology as well as avenues for future research. • A three-dimensional tiering typology consists of delegation, direction and strength. • Early EA can delegate actions of tiering to later EA levels. • Avoiding disrupted tiering and encouraging explicit tiering is crucial for practice. • A case study shows delegated, non-delegated, successful, weak and disrupted tiering.