Corridor Planning Guidebook

Evaluation and Refinement

Once an initial set of solutions has been developed to the satisfaction of the project team, evaluate the solutions using a systematic and transparent process. Evaluation is an iterative process, often leading to refinement and reevaluation of the initial solutions (see discussion below). As noted above, public and agency partner input should be documented separately from the results of the technical evaluation.

Evaluation Criteria

Table 15 provides a base set of topics, criteria, and measures for evaluating solutions developed in a corridor plan. Most criteria will be applicable to most corridor studies. Variations from the identified items should be documented in the evaluation report.
The evaluation criteria were developed to respond to the data collected in Step 2 and Step 3, which are framed around the SMTP objectives. In this way, the evaluation process is designed to understand how a given solution is aligned with those objectives.
Detailed evaluation results should be documented in a table and/or a technical memorandum. Various methods may be used to translate technical results into a simplified rating to allow for comparison across alternatives. Use of a three-point scale (such as good/fair/poor) is common but not necessarily applicable to all criteria (some criteria may be pass/fail; others may require greater differentiation). Regardless, logical breakpoints between rating levels should be documented and defensible, such as in the example below.

• Good: no impacts foreseen
• Fair: potential or likely impact on one resource
• Poor: potential or likely impact on two or more resources

See Appendix C: Plan Type Data Matrix for a summary of Step 4 data items as they relate to the different plan types (Corridor Project Plan, Corridor Vision Plan, and Regional Corridor Vision Plan) and adjust efforts as needed.

Relation to NEPA/MEPA

Most infrastructure solutions identified in a corridor plan will be required to go through an environmental review (NEPA/MEPA) process before advancing to design and construction. Corridor plans prepared following the Guidebook can be useful and productive inputs to a subsequent environmental review process but typically are not prepared for the same purpose to the same requirements.

Specifically, the NEPA/MEPA process is intended to evaluate the environmental and related social and economic effects of a proposed action, whereas the corridor planning process is a broader process for identifying future needs and opportunities and potential solutions to address them. Environmental clearance requires development and evaluation of a range of alternatives in response to a statement of Purpose and Need based on specific Primary and Secondary Needs categories and associated criteria and measures. In contrast, the Guidebook evaluation criteria respond to the objectives of the SMTP (Table 14). While the two processes overlap, they are substantially different both in purpose and technical content. The federal Planning and Environmental Linkages (PEL) process and state equivalents have been developed as a method to integrate the two processes and improve efficiency. However, the PEL process is currently on pause at MnDOT and is not accounted for in the Guidebook at this time.

To preserve its value for a subsequent NEPA/MEPA process, the corridor plan should not identify a preferred alternative, which is reserved for the environmental review process. While solutions identified in a corridor plan are valuable inputs to the NEPA/MEPA process, that process must draw its own conclusions with regard to performance against Purpose and Need and subsequent recommendation of a preferred alternative. If the corridor plan identifies a preferred alternative, this conclusion is not valid for NEPA/MEPA and renders the corridor plan much less useful in that process. However, a pre-NEPA planning process such as a corridor plan can develop a short list of alternatives to be carried into NEPA.

If a corridor plan is intended to be used directly to develop a NEPA statement of Purpose and Need, the user should refer to NEPA guidance in the MnDOT Transportation Project Development Process (TPDP) so that the scope of work for the corridor plan can be modified to include additional data collection, analysis and evaluation consistent with those requirements. This may also include preparing documents such as a Purpose and Need Statement, Logical Termini Memorandum, and Alternatives Evaluation Report, each with their own specific format and content requirements.

Table 14 . Comparison of Guidebook and NEPA Evaluation Categories

Solutions Refinement

The process of developing solutions can range from simple (a small number of solutions that are generally agreed upon) to complex (many potential solutions and variations on those solutions and a wide range of options and opinions about them).
As solutions are identified and evaluated, new understanding and ideas typically emerge, resulting in a refinement of the initial ideas and updated evaluation. In addition to refinements that seek to better address the identified issues and opportunities, the following variations may be considered.

• Single Solution vs. Phasing: In addition to or instead of a single solution that may fully address the identified issue and opportunities, are there phases or pieces of the option that could stand alone or serve as an initial phase while also providing benefits but at less cost and with less impact?
•  Mix and Match Components: Are there components of different solutions that could be combined differently to produce other possible solutions?

Greenhouse Gas Emissions Reduction Requirement

• As part of responding to Minnesota Statute 161.178 (passed in 2023 and updated in 2024) requiring net zero greenhouse gas (GHG) emissions (100% reduction from 2005 levels) by 2050, MnDOT has developed goals for lowering GHG emissions. As described elsewhere in the Guidebook (Step 3: Climate Action), the statute requires that trunk highway capacity expansion projects in Minnesota undergo a greenhouse gas emission analysis, including identifying measures to offset GHG increases. The legislation defines a capacity expansion project as one that adds highway traffic capacity or provides for grade separation at an intersection, excluding auxiliary lanes with a length of less than 2,500 feet, or is a major highway project with a total cost of $15,000,000 in the metropolitan area or $5,000,000 outside of the metropolitan area.
• If a concept identified in a corridor plan meeting the capacity expansion definition advances in the Transportation Project Development Process (TPDP) and is refined during scoping, then an Emissions and VMT Impact Assessment and Offset Plan may be required. This could impact the project’s timeline, scope and budget.