4.3.2 Multiple Alternatives along the Preferred Route
Once the preferred route is selected, the design is optimized by evaluating alternate typical sections, horizontal and vertical alignments and intersections.
The principles of Performance Based Practical Design (PBPD) as described in the RDM should be used to ensure that the design alternatives considered meet the project’s goals and objectives and related criteria that were established during project scoping.
This is an iterative process and may result in one or more alternatives to present to the public to obtain stakeholder feedback.
4.3.2.1 Roadway Typical Section and Alignment Alternatives Refinement
Roadway typical sections should be optimized, and horizontal and vertical alignments more fully developed to determine the best alignment for the project. Some options that are typically considered in this refinement include:
- Roadway typical sections:
- Different lane and shoulder widths;
- Use of medians (depressed, flush, or raised);
- Sidewalks and ADA ramps; and
- Bicycle accommodations, etc.
- Alignments:
- Shifting alignments to one side of the road or the other (e.g., eastern alignment vs. western alignment);
- Using the existing alignment of the road;
- Using a combination of existing alignment and alignment shifts;
- Vertical clearances for structures; and
- Sight distance requirements
4.3.2.2 Intersection Control Evaluation
It is important to perform Intersection Control Evaluation (ICE) at this stage in project development to determine the intersection type that best increases safety and operations. The ICE process is typically used in evaluating the intersection traffic and geometric control at new or modified intersections.
ICE provides a framework of quantifiable measures to evaluate alternatives so that public agencies, engineers, and planners make enhanced and more informed decisions. Quantitative measures are considered alongside qualitative measures such as multimodal needs and community vision goals to provide a well-rounded perspective when selecting the preferred alternative.
Refer to TxDOT’s TSAP for guidance on performing a Stage 1 and Stage 2 ICE analysis. Similar to typical sections and alignments, the intersection controls need to consider cost, ROW, environmental impacts, utility impacts, etc. as part of the intersection type determination.
illustrates the ICE Stage 1 and Stage 2 workflows.
Refer to the ICE directive published by DES.
Figure 4-4: ICE Stage 1 and Stage 2 Workflows
4.3.2.3 Potential ROW Needs, Utility Conflicts and Environmental Impacts Identification
For each alternate developed for evaluation, the amount of potential ROW needed, utility conflicts and obvious environmental impacts are identified along with any “fatal flaw” elements that may eliminate an alternative (e.g., high-pressure gas line along one side of the roadway, cemetery or historical structure).
4.3.2.4 Alternative Alignment Layouts Development
If needed, alternate alignment layouts are developed for each alternative for review by the District and presentation to the public to obtain stakeholder feedback.
If the layouts are being prepared for public display, they should be developed similarly to the conceptual route layouts described in
– the layouts should be easily understood by the public. Additional details such as proposed ROW, locations of ramps, control of access, dedicated bike/ped facilities, dedicated transit facilities, retaining wall locations, bridge structures, driveways, existing utilities and intersection types are shown on the layouts at this stage.
4.3.2.5 Alignment Alternatives Cost Estimates
Construction and ROW cost estimates are developed for each of the alignment alternatives to assist in the evaluation and selection of a preferred alignment. Update the planning level estimate for each alternative using TxDOT’s CCEG and CCEG spreadsheet tool (see
).
If funding authorization involves federal funds and the preliminary estimates indicate the total project cost may approach the threshold for a VE Analysis (see
), contact the DES to discuss options.
4.3.2.6 Public Meetings for Alignment Alternatives
If desired, a public meeting can be conducted to obtain additional input from stakeholders on the alignment alternatives. The public meeting should be organized and conducted similarly to the conceptual layout public meeting described in
.
There are many options for engaging the public beyond, or in addition to, a public meeting. There are also many effective ways to promote public engagement opportunities. Consult with TPP – Public Involvement Section for assistance.
If the project is going through the NEPA process (see
), coordinate all public involvement with the District Environmental Coordinator to ensure that all engagement with the public is documented correctly and included in the environmental document.
4.3.2.7 Alignment Alternatives Analysis
Each alignment alternative is evaluated based on scoring criteria as determined by the project’s purpose and need and goals and objectives. Evaluation of alignment alternatives typically involves more detailed analysis and determination of project level impacts.
The project team along with appropriate SMEs determine the scoring criteria to be used for evaluation of the alternatives and any associated weighting of criteria. Commonly used scoring criteria of multiple alignments includes:
- Safety;
- Mobility;
- Access;
- ROW costs;
- Utility impacts;
- Environmental impacts;
- Funding; and
- Project specific objectives.
The alignment alternatives analysis is documented as described in
and coordinated with the District Environmental Coordinator.
depicts an alternatives analysis matrix used to compare different alignments within different route segments.
Figure 4-5: Example of Alignment Alternatives Analysis Matrix
4.3.2.8 Recommended Alternative Selection
Once the alternatives are independently evaluated, analyzed and documented, the recommended alternative is selected and is used to develop the geometric schematic for final approval.
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