8.2.5 Evaluate Alternatives

After alternatives and evaluation criteria have been defined, each alternative is assessed based on selected criteria. For example, for the safety evaluation criteria, safety performance of the alternatives is evaluated. Design elements should be modified to optimize safety. Alternatives are analyzed using a welldefined, developed, calibrated, and validated baseline model.
Sensitivity analysis is used in the decisionmaking process for choosing among alternatives or for determining which alternatives maintain a certain level of mobility or safety. For example, sensitivity analysis could be performed by increasing traffic projections by 5 to 15 percent to determine how the study area would operate with increased traffic. Procedures for conducting traffic analyses are detailed in
Chapters 4, 9, 10, 11, 12, 13,
 and
14
.
Alternative Evaluation Guidance:
  • 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). (quantitative evaluation results
    example
    ) and (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.
Table 8-3: Quantitative Evaluation Results Example
Criterion Type
Criterion
Unit
Alternatives
No Build
Extend Widening
Couplet
Bypass
Safety
Predicted crash frequency
Crashes per Year
60
60
50
40
NPV of crash savings
Dollars
$-
$-
$10,000,000
$20,000,000
Mobility
LOS - Intersection 1
Grade
C
B
C
F
Delay - Intersection 1
sec/veh
25
18
87
21
LOS - Intersection 2
Grade
B
B
D
C
Delay - Intersection 2
sec/veh
14
10
51
26
Access
Bicycle lane-miles
Miles
-
3
6
-
Transit lane-miles
Miles
-
3
6
8
Other
Proposed ROW Acquisition (Actual)
Square Feet
105,037
105,037
91,016
121,489
*Residential Parcels Impacted
Number
19
19
25
104
*Commercial Parcels Impacted
Number
-
-
1
-
Cost
Dollars
$1,000,000
$8,000,000
$12,000,000
$15,000,000
*Impacted is defined as parcels with ROW is impacted by the alternative design
Table 8-4: Qualitative Evaluation Results Example
Criterion
Measures
Alternative with *Rating (1-5)
No-Build
Extend Widening to Third Street
One-Way Couplet
Two-Lane Elevated Bypass
Safety
Conflict points and driver expectancy
2
Merge, no access management
4
No merge, installed access manageme nt
4
Two-to-one-way conversion, introducing uncommon operation, fewer conflict points at intersections
2
High speeds, introducing uncommon operation
Mobility
Travel speed, roadway capacity, and intersection capacity (Delay and LOS)
1
No increased capacity
3
Increased capacity
4
Increased capacity, fewer phases at traffic signals
5
Increased capacity
Access
Property entry/exit points and local route distance
4
No access management
3
Restricted access (raised median)
2
Limits access, increases trip distance
1
Access controlled
Property Impacts
Environmental and historic impacts
5
No ROW necessary
3
50-foot ROW necessary
5
No ROW necessary
1
100-foot ROW necessary
ROW Cost
Cost of ROW expected to be purchased
5
No ROW necessary
3
50-foot ROW necessary
5
No ROW necessary
1
100-foot ROW necessary
Construction Cost
Cost of materials to construct improvements
5
No improvement
3
Widening Main Street
3
Reconstructing Main Street, widening Washington Avenue
1
Elevated structure, widening Main Street
Development Potential
Potential economic benefits
2
None
3
Increased volume
5
ROW made available for social/aesthetic improvements
1
None
*Rating scale is from 1-5. 1 signifies the best rating and 5 signifies the worst rating
  • 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.