Estudio de alternativas

En el mundo anglosajón los estudios de alternativas, o estudios multicriterio, se hacen de forma distinta de como se hacen aquí. Creo que entre otras cosas, es por motivos culturales, de cómo se sacan adelante los proyectos en España y como se sacan en los países sajones.

He hecho este esquema sobre cómo se estudian distintas alternativas en EEUU, en inglés, por supuesto!

SCREENING PROCESS

1.       Purpose and needs document.

                    I.     Main purpose of the project.

                  II.     Needs: issues the project should address.

                III.     Goals: product-by of the purpose and needs. General statements, usually relating the following fields: Access, Capacity, Community, Environment, Implementation, Infrastructure, Mobility, Safety and Security.

                IV.     Objectives: concrete things to achieve in order to accomplish the goals.

2.       Define a variety of alternatives to consider:

                    I.      Define a full range of relevant transportation elements, grouped in different categories (alignments, interchanges, lane types or local system improvements, for example).

·        Each element represents a different option or alternative to be assessed.

·        Elements can range from road expansions in different configurations to new infrastructures (LRT, BRT), alignment displacements, changing lane types (HOV, HOT) or cross section modifications. Any action that impacts transportation can be considered.

·        This elements are to be evaluated and filtered through stages I and II of the screening process (Initial screening and Comparative screening), rejecting those options that do not meet the criteria set for each stage of the screening process, for each Goal.

                  II.     Remaining elements are combined to form project alternatives (full corridor alternatives, for example).

·        Each alternative define a potential project-to-be to be assessed.

·        Formed alternatives are to be evaluated and filtered as a whole through stages III and IV of the screening process (Detailed screening and alternative refinement).

                III.     Some elements might not be evaluated as stand-alone alternatives, since they do not individually address project purpose and needs, but could be combined with other alternatives as necessary to improve overall operations. (Transportation demand management –TDM- or Transportation system management – TSM- to reduce transportation demand, for example)

                IV.     To make the list more manageable, some categories or even the project as a whole can be divided in sections (four sections to consider different alignments, for example.).

3.       Screening process:

                    I.     Initial screening (of Alternative Elements): Qualification Evaluation.

·        Define Initial Screening Evaluation Criteria for each Goal.

·        For each element, evaluate whether it complies with the criteria set.

·        Yes/No answers.

·        Discard Elements that do not comply with any of the goals (any “No”). Provide reasons for elimination and summarize in an easy to compare table.

·        Submit results to public opinion.

                  II.     Comparative screening (of Alternative Elements): Qualitative Evaluation.

·        Define Comparative Screening Evaluation Criteria for each Goal.

·        Define Evaluation Measures: For each criterion in the evaluation criteria for each Goal, define what will it take for any Element in a category to meet the criterion in a good, better or the best way (Ex. Any element in the Alignment category will be considered to meet the “Provides access to local residences” criterion for the “Access” Goal in a good way if the alignment is located outside of the corridor, in a better way if it located partially in the corridor, and in the best way if it is located entirely in the corridor).

·        Evaluation Measures can be absolute, or relative between alternatives (Ex. An element can be considered “Best” under an environmental criterion if it has no relevant impacts -absolute- or if it has the least impacts among considered Elements -relative-).

·        Some categories of elements may not be evaluated under every Criterion for each Goal: some criteria are not suitable to evaluate certain categories (i.e. it might not be interesting to evaluate “interchanges“ category by “Minimizes project costs” criterion under Implementation Goal):

·        Evaluate Elements that were not eliminated in the Initial Screening, rating them good/better/best depending on the Evaluation Measures the Element meets for each Criterion.

·        Discard unreasonable alternatives. Provide reasons for elimination and summarize in an easy to compare table.

·        Present results to the public.

ð The remaining elements after the two first screening levels are combined to form several alternatives for the project as a whole (i.e. alternatives for the corridor, not its single elements). Those consolidated alternatives are to be evaluated in the next screening levels.

                III.     Detailed screening (of Corridor Alternatives): Quantitative evaluation.

·        Define Detailed Screening Evaluation Criteria for each Goal. Use statements that are easy to quantify. Clearly state how to measure each alternative as well as any assumptions to be made for each Criterion (i.e. Travel times will be measured from existing traffic model in 2025. or the cost ratios to be used).

·        The objective is to be able to define each alternative comprehensibly and numerically.

·        Measure each alternative to quantify its performance for each criterion. Measure by sections if the study was divided by sections: Each section may need a different alternative.

·        Answers will generally be numbers, although certain criteria might need to be assessed qualitatively instead (good/better/best) if they are difficult to measure (i.e. Daily tons of CO mobile source emissions).

·        Discard Elements that score unsatisfactory records. Provide reasons for elimination and summarize the results.

·        Submit results to public opinion. Further recommendations for discarding or modifying alternatives can be made.

                IV.     Alternative refinement (of Corridor Alternatives).

·        Remaining alternatives are developed in more detail and further analyzed.

·        This screening level should consider Engineering Feasibility, potential effects on social, environmental and economic resources (Resource-Specific Evaluation), and an analysis of capital, operation and maintenance costs (Cost Analysis).

·        Specific tables can be prepared in order to compare different alternatives on specific issues, measuring them by convenient criteria.

·        Even at this last screening level, some alternatives can be discarded just because they do not meet the initial purpose and needs.

·        The result is a series of reasonable build alternatives that have been fully evaluated.

ð The screening process can be applied to any decision process. A simplified version (maybe with only I and II screening levels) can also be applied to some lesser elements like Interchange forms within an alternative.

ð They key aspect when comparing this process with the Spanish one is that this process is an ongoing, living effort, with continuous modifications as stakeholders meet and make comments, whereas Spanish process seeks maximum clarity and objectiveness, resulting in a much more rigid system.