Section 2: Advanced Planning
Anchor: #i1001398Overview
Once a project has LRP status, the Texas Transportation Commission authorizes advanced planning activities to proceed. This phase of project development involves the environmental and public involvement process of project planning to consider reasonable alternatives, prepare preliminary schematic design for the preferred alternative, and determine right-of-way requirements. Advanced planning identifies the improvement that best addresses the design year travel demand, is cost-effective, and is publicly and environmentally acceptable.
Depending on the location, the type of project, and the number of reasonable alternatives, advanced planning may consist of one or more stages of analysis. Ultimately, however, TPP develops the directional design-hour volumes (DDHV) required to analyze the preliminary schematic plan.
Three series of traffic forecasts may be needed during this stage of project development. Each successive stage of analysis requires an increasing level of detail and accuracy.
- Forecasts for the initial evaluation of alternatives - Traffic detail required for this stage of analysis is sufficient to identify the typical cross-sections and prepare the horizontal alignment of various alternatives on aerial photography.
- Forecasts for the evaluation of selected alternatives - Traffic detail required for this stage of analysis is sufficient to evaluate design variations between the selected alternatives, including variations such as location and design of access and intersections with cross streets. The traffic provided should enable an accurate definition of the cross-section of the preferred alternative and any reasonable variations at the conclusion of this stage of project development.
- A forecast for the preferred alternative - Traffic detail required for this stage is sufficient to form the basis for preparing design-hour volumes for use in preparing a preliminary schematic design and determining right-of-way requirements.
Traffic Data Provided
The exact traffic data provided will depend on the range of improvements considered and the evaluation criteria set for the project. The following lists show typical traffic data provided in each stage.
Initial Evaluation of Alternatives. Data typically includes:
- base year traffic assignment
- build and design year unadjusted directional or non-directional ADT
- estimates of the peak-hour percentage for the build and design years
- estimates of the percentage of trucks for the build and design years
- average speed, travel time, and/or delay for the build and design years
- daily VMT for the build and design years
- daily vehicle hours of travel for the build and design years
Evaluation of Selected Alternatives. Data typically includes:
- build and design year directional or non-directional ADT including ramp, interchange, and intersection volumes
- build and design year daily and peak-hour average speed, travel time, and/or delay
- build and design year daily or peak-hour VMT
- build and design year daily or peak-hour vehicle hours of travel
Evaluation of Preferred Alternative. Data typically includes:
- build and design year directional ADT including ramp, interchange, and intersection volumes and turning movements
- build and design year peak hour volumes including ramp, interchange, and intersection volumes and turning movements