Objectivity:

It is suggested that evaluation criteria aim to be objective and without bias.

Criteria groups:

Evaluation criteria that represent a range of project impacts and reflect all project goals/objectives selected. Common criteria groups include safety, mobility, access, environmental, and cost (see

Figure 8-2

).

Quantitative criteria:

Quantitative criteria are preferred and can include the MOEs discussed in

Chapter 4

. Common quantitative criteria include crash rate, crash frequency, LOS, impacted residential parcels, and OD travel times.

Qualitative criteria:

For high-level evaluations where MOEs may not be feasible, qualitative criteria can be precisely defined and criterion scoring can be annotated. Examples of qualitative criteria are conflict points and driver expectancy. Conflict points help identify potential safety issues. Driver expectancy is another qualitative criterion that relates to a driver's readiness to respond accurately and promptly to situations, events, and information while driving.

Quantitative comparison:

Quantitative metrics can be reported for each alternative and then qualitatively “scored” to compare impacts between criteria.

Trade-offs:

A wide range of criteria can be employed to highlight benefits and costs of each alternative. This certifies trade-offs, or specific costs associated with selected benefits, are evaluated as part of the decision-making process.

Weighting criteria:

Trade-offs can be plainly demonstrated by weighting criteria; weights are assigned in proportion to the importance of each criterion. However, weighting criterion, as with assigning exact values to qualitative criterion, may misrepresent project impacts or over-complicate the alternatives analysis.

Redundant criteria:

It is recommended that redundant criteria (such as intersection LOS and control delay) be valued appropriately to avoid double-counting impacts.

Multi-tier alternatives analysis:

Evaluation criteria can differ between evaluation tiers (see

Table 8-1

). For example, a Tier 0 (fatal-flaw) analysis can evaluate twelve Planning-level alternatives using sketch-level or macroscopic tools. A Tier 1 (preliminary) analysis can evaluate six Preliminary Schematics-level alternatives using HCM-based (mesoscopic) tools. A Tier 2 (detailed) analysis can evaluate three Advanced Schematics and Design-level alternatives using microsimulation (microscopic) tools.

Number of alternatives:

Varies by project scope and level of detail. A large number of alternatives are refined using a multi-tier screening process. Generally, three to five alternatives are evaluated in detail as the final analysis tier.

Level of Analysis:

Alternatives are developed with sufficient detail to adequately evaluate benefits and costs. Alternatives typically increase in detail (additional attributes characterizing each alternative) as the number of alternatives is reduced.

Timeframe:

Alternatives can be short-, mid-, or long-term. Short-term alternatives are often developed in more detail, while long-term alternatives have less detail (sketch-level).

Type:

Alternatives include infrastructure improvements, Transportation Demand Management improvements, and Transportation System Management (TSM) improvements (see

Section 15.2.2 and 15.5

in

Chapter 15

).

Nomenclature:

Name alternatives to be easily understood and distinguishable. Improvements for each alternative are directly stated.

Description:

Alternatives are often depicted graphically and described narratively, denoting key aspects (see

Figure 8-3

). If alternatives vary by specific elements (such as ROW, cross section, etc.), it is recommended they be represented in a matrix (see

Table 8-2

).

No-Build Alternative:

A no-build (base condition) alternative that represents future conditions without proposed project improvements is typically included as a benchmark for comparison. A no-build alternative typically considers existing conditions with committed projects. Any project expected to be complete prior to the analysis build year and included in a fiscally constrained funding program may be included in the no-build alternative. The no-build alternative serves as the baseline for analyzing other alternatives, so it is recommended that particular care be given when developing the no-build alternative.

Traffic Projections:

Baseline and future year traffic projections for the no-build scenario are typically used for each build scenario. However, it is recommended the build alternatives selected for evaluation be reviewed to determine whether new traffic projections are mandatory to represent the proposed improvements. This is common for access changes, new alignments, and locations where the existing corridor is capacity-constrained, resulting in detours. These detours are captured using the DTA routing methodology found in some microsimulation models. For regional and larger study areas, TDM outputs are often used to determine changes in travel patterns. For smaller corridor- or intersection-level studies, these changes can be assigned manually.

Multi-tier alternatives analysis:

Complex projects could necessitate alternatives to be developed and evaluated in sequence, with increasing levels of detail. Alternatives evaluated in subsequent tiers are typically based on evaluation results of prior tiers.

Transportation System Management and Operations (TSMO) strategies;

Transportation demand management improvements;

Transportation system management improvements;

Access control and local circulation changes;

Multimodal and intermodal improvements;

Safety solutions;

Segment improvements;

System improvements;

Intersection improvements; and

Interchanges

Levels of Alternatives Analysis:

Different levels of alternatives analysis are performed based on the scope, size, and complexity of the project. Network/corridor-level alternatives have a bigger scale and regional impact; these alternatives can use sketch-level or macroscopic tools or TDM outputs to assess alternatives. Intersection or interchange-level alternatives analysis are more localized and location-specific, so deterministic tools, traffic signal optimization tools, or simulation tools can be used to compare alternatives. Comparing alternatives includes comparing different build scenarios to the no-build scenario.

Evaluation Results Narrative:

It is recommended that evaluation results comprehensively describe the benefits and costs of each alternative. Evaluation results are typically described narratively and organized such that the preferred alternative is evident. Provide justification explaining how the preferred alternative meets project evaluation criteria and satisfies the project’s purpose and need.

Evaluation Results Matrix:

Evaluation results are typically summarized in a matrix (alternatives versus evaluation criteria).

Table 8-3

(quantitative evaluation results

example

) and

Table 8-4

(qualitative evaluation results

example

) present

examples

of evaluation results.

Discarded Alternatives:

Evaluation results clarify why non-selected alternatives were discarded. Discarded alternatives are documented.

Scoring:

Generally, quantitative analysis results are converted to qualitative scores that are then compared to identify the preferred alternative.

B/C Analysis:

Benefits and costs of each alternative are typically monetized so that alternatives can be compared economically. HSM procedures are typically used to monetize safety impacts. TxDOT’s Road User Cost (see

Appendix I, Section 2 – External References (Reference 2)

) can be used to monetize vehicle operating impacts.