The PDS describes the position of a project in its life cycle. The three main PDSs are:

The PDS can be considered multi-stage if it includes a combination of Planning, Preliminary Schematics, or Final/Approved PS&E. The PDS is one factor to determine which analysis tool will be used for a project. For more information about the PDS, see

Chapter 4, Section 2

. See

Table 1-3

for an example of how to fill out this section.

The level of detail is different than the PDS and describes the detail necessary to complete an analysis. Analysis tools are often categorized into varying levels of detail. The necessary level of detail for an analysis, as well as project scope and complexity, often influence tool selection. Level of detail is divided into three categories:

Like the PDS, the level of detail can also be considered multi-resolution if the analysis includes a combination of Sketch-Level or Macroscopic, HCM-Based (Mesoscopic), and Microsimulation (Microscopic) tools. Use the PDS and level of detail to guide the selection of appropriate tools for analysis. Determination of level of detail (including multi-resolution modeling) for scoping is based on a variety of factors; work with the TxDOT project manager, TxDOT’s Design Division (DES), and/or TPP to determine which level of detail fits for the project. See

Table 1-3

for an

example

of how to fill out this section.

Analysis tools typically used in safety-related projects include TxDOT’s Safety Scoring Tool (SST), Safety Performance of Intersection Control Evaluation (SPICE), HSM for Rural Multilane, HSM for Urban/Suburban Arterials, HSM for Rural Two-Lane Roads, Enhanced Interchange Safety Analysis Tool (ISATe), Highway Safety Software (HSS), and Interactive Highway Safety Design Model (IHSDM). These tools are often used to achieve results varying in level of detail.

The scope of work is an agreement on the work to be performed for a project. The basic scope of work is defined by the type of project (e.g., new roadway, adding capacity, operations analysis, signal analysis, corridor study, planning study, safety study, toll feasibility analysis, etc.) and is specified on the

Scoping Form

. Preventive Maintenance (PM) and resurfacing or restoration (2R) projects typically do not involve traffic analysis. Resurfacing, restoration, or rehabilitation (3R) projects may involve traffic analysis, especially if roadway geometrics are changed. Reconstruction (4R) projects typically involve traffic analysis. The level of detail depends on the project scope. It is recommended that a description of the scope of work be included and answer questions such as:

During the project scoping meeting, refine the scope of work and modify it as agreed-upon.

State within the Scope of Work if PBPD will be used. PBPD is a decision-making approach to better manage transportation investments and serve system-level needs and performance priorities with limited resources. PBPD uses performance evaluations during project development to guide alternative selections and, ultimately, geometric design decisions. During the planning stage, PBPD defines system and project purpose and need, develops concise project objectives from the purpose and need, considers project in the context of the system, and addresses all users. PBPD is based on quantitative analysis for system performance, operations, or safety, and allows for flexibility in design while still meeting project objectives. During preliminary engineering and design, PBPD develops solutions that meet the purpose and need and evaluates tradeoffs based on objective analysis of data. PBPD analysis includes a cost-benefit analysis.

Table 1-2

shows operational and safety tools that incorporate PBPD. When used in planning and design, these tools can be used to compare and select alternative designs based on the operations and/or the number of predicted crashes for each alternative. Costs include cost of constructing or implementing improvements and cost of maintenance. Benefits are calculated in terms of delay savings and crash reduction savings. For more information on Cost-Benefit Analysis, see

Chapter 10, Section 10.3.6

. Refer to TxDOT’s RDM for additional information on PBPD.

The geographic (spatial) limits include the project improvement locations (project area) and the area impacted by the project improvement (study area). Spatial limits for operation and safety are typically the same. For spatial limits, it is recommended to attach a map to the

Scoping Form

. For an

example

of the spatial limit map, see

Figure 1-1

.

Below are sample prompts that may provide guidance:

Time (temporal) limits for an operational analysis include the analysis years and analysis periods. Typical analysis years often include the following:

The analysis years listed above are typical, but can vary based on project type (e.g., resurfacing, restoration, or rehabilitation projects often have analysis years of five to 10 years). Pavement design year is used for traffic projections but is not needed for traffic analysis. It is typically 10 years after the design year and represents useful life of the pavement. The analysis period is the time of day when the analysis will be conducted.

Typical traffic analysis time periods (temporal limits) include a weekday AM peak and a weekday PM peak. There are situations that warrant different analysis periods (e.g., analysis of a facility near a school, mall, or sports arena; analysis of a facility with heavy weekend traffic). Part of the scoping process is identifying the analysis day(s) and the analysis periods (e.g., AM Peak: Tuesday-Thursday, 7:15AM – 8:15AM).

Temporal limits for a historical safety analysis typically include the most recent three to five years. Temporal limits for a predictive safety analysis typically include the opening and design years. For projects that need FHWA approval, request Crash Records Information System (CRIS) data through TxDOT's Traffic Safety Division (TRF) or the Design Division.

Below are sample prompts that may provide guidance on selecting temporal limits:

It is suggested that background factors which may influence the project are included on the

Scoping Form

. These background factors may include planned roadway improvements (geometric, operational, safety, etc.), planned developments (developments that change traffic patterns), input from various TxDOT groups, and other factors that have an influence on travel and safety. It is recommended that a preliminary project schedule be attached to the

Scoping Form

when sharing the document with the TxDOT project manager. The project schedule establishes the start date and completion date of the project and includes major project milestones (e.g., project administration, data collection, traffic analysis, safety analysis, agency coordination, renderings, and work authorization termination date). For an

example

, see

Appendix B, Section 3 – Example Project Schedule

.

Table 1-3

is an

example

of a completed project description section on the

Scoping Form

.