8.2.3 Alternative Development Guidance

  • 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 ). If alternatives vary by specific elements (such as ROW, cross section, etc.), it is recommended they be represented in a matrix (see ).
No Build
  • West of First Street, Main Street is a six-lane roadway with two-way operation
  • East of First Street, Main Street is a four-lane roadway with two-way operation
  • Washington Avenue is a two-lane roadway with two-way operation
Alternative 1 – Extend Widening to Third Street
  • West of Third Street, Main Street is a six-lane roadway with two-way operation
  • East of Third Street, Main Street is a four-lane roadway with two-way operation
  • Washington Avenue is a two-lane roadway with two-way operation
Alternative 2 – One-Way Couplet
  • West of First Street, Main Street is a six-lane roadway with two-way operation
  • East of First Street, Main Street is a three-lane roadway with one-way operation
  • Washington Avenue is a three-lane roadway with one-way operation
Alternative 3 – Two-Lane Elevated Bypass
  • West of First Street, Main Street is a six-lane (at-grade) roadway with two-way operation
  • Between First Street and Second Street, Main Street has two-way operation and is a four-lane roadway (at-grade) and a two-lane roadway (above grade)
  • East of Second Street, Main Street is a four-lane (at-grade) roadway with two-way operation
  • Washington Avenue is a two-lane roadway with two-way operation
Figure 8-3: Narrative Description of Alternatives Example
  • 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.
Table 8-2: Matrix Description of Alternatives Example
Nomenclature
Main Street Characteristics
Washington Avenue Characteristics
Alt.
Description
Lanes
Traffic Flow
Grade
Lanes
Traffic Flow
Grade
No Build
Widening terminates at First Street
4/6
Bi-Directional
At-Grade
2
Bi-Directional
At-Grade
1
Extend Widening to Third Street
6
Bi-Directional
At-Grade
2
Bi-Directional
At-Grade
2
One-Way Couplet
3
Westbound
At-Grade
3
Eastbound
At-Grade
3
Two-Lane Elevated Bypass
6 (2 by .)
Bi-Directional
At and Above
2
Bi-Directional
At-Grade