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.
