Trans-Texas Corridor Glossary

Alignment

A specifically defined path in which transportation facilities are constructed. A TTC facility’s alignment will vary in width depending on need, and will not be identified until TTC Tier Two studies are complete.

Comprehensive Development Agreement (CDA)

An agreement with a private entity for the planning, design, acquisition, financing, construction, reconstruction, extension, expansion, operations or maintenance of a project.

Corridor Alternative

A broad geographic band in which high-level environmental studies and transportation analyses are conducted for purposes of narrowing project alternatives and limits. For current TTC projects, the goal of the Tier One environmental process is to identify a preferred corridor alternative that would serve as the study area for future Tier Two alignment-level studies.

Draft Environmental Impact Statement (DEIS)

An environmental document required under the National Environmental Policy Act of 1969 (NEPA) and prepared when a major federal action is proposed that could potentially have significant impacts on the environment. The DEIS reports the results of the environmental analyses and compares reasonable alternatives. See also, FEIS

Facility

Each separate transportation or utility project of the TTC, including all improvements, amenities and related development.

Federal Highway Administration (FHWA)

Federal agency of the U.S. Department of Transportation (USDOT) responsible for administering federal highway funds and ensuring compliance with federal environmental laws. FHWA is a lead agency for both the TTC-35 and I-69/TTC projects.

Final Environmental Impact Statement (FEIS)

An environmental document required under NEPA and prepared after the public comment period for the DEIS has ended. The FEIS summarizes and responds to new and substantive comments received during the DEIS comment period, documents compliance with applicable environmental laws, and makes a recommendation for how the project should proceed. See also, DEIS

Master Development Plan (MDP)

A dynamic, visionary, and long-term plan for the development of a transportation project. The TTC MDPs include, but are not limited to the following: a master financial plan that identifies potential public and private funding options; descriptions, implementation schedules, conceptual designs, preliminary traffic and revenue studies, and cost estimates and funding sources for specific near-term, mid-term, and long-term facilities that could be developed as part of TTC; and potential plans, approvals, third-party agreements, and environmental mitigation strategies needed to develop individual facilities. The MDP will continue to be updated as environmental decisions are made (through the NEPA environmental process) and as new planning and financial information and local input become available.

Mitigation

Any technique or measure undertaken to avoid or minimize adverse impacts to the environment caused by a proposed action. Because TTC Tier One environmental processes focus on broad, corridor-level issues and a Tier One decision would not authorize construction, specific mitigation measures for TTC facilities would not be identified until Tier Two.

Modal Transition Zone (MTZ)

Areas within the TTC study areas where transportation modes (auto, truck, rail, and utilities) would be routed to connect with existing and planned facilities within the MTZ. Potential connections to facilities within the MTZs would be studied in cooperation with local elected officials and planning organizations during the Tier Two environmental processes.

Mode

A particular form or method of transportation used to move people or goods. Modes, for purposes of TTC studies, include highway (for passenger vehicles and commercial trucks), rail (for freight, commuters, and high-speed passenger service), and utilities.

National Environmental Policy Act of 1969 (NEPA)

Federal legislation signed into law in 1970 and subsequently amended to established national policy, goals, and implementation processes for protecting, enhancing, and maintaining the environment. NEPA specifically requires all federal agencies (including FHWA) to prepare detailed statements of environmental analyses and findings when a major federal action is proposed that could potentially have significant impacts on the environment. The TTC-35 and I-69/TTC environmental processes follow the standards required by NEPA. See also DEIS and FEIS.

Potential Connecting Facility

A facility that offers a financing or connectivity purpose for the TTC and has completed or will complete a separate, stand-alone environmental clearance process.

Potential Connection Zone (PCZ)

Area in which a TTC project could potentially terminate or connect to existing or future state or international border facilities. The PCZs identified in TTC Tier One studies are intentionally broad because alignments have not yet been proposed. Potential logical termini and connections to other facilities within the PCZs would be studied in cooperation with local elected officials and planning organizations during the Tier Two environmental processes.

Preferred Corridor Alternative

The alternative recommended in a Tier One environmental study as the preferred corridor (narrowed study area) for future Tier Two alignment-level studies.

Preferred Modal Corridor (TTC-35 only)

A corridor in the Dallas/Fort Worth region that would serve as the basis for future TTC-35 Tier Two mode-specific studies. Within this preferred modal corridor, modes could be combined or separated based on specific transportation needs and local transportation plans.

Primary Facility

A TTC-specific facility that could be constructed upon completion of Tier Two environmental studies and in response to a demonstrated transportation need. These facilities would serve as TTC main arteries, with potential connecting facilities playing a supporting role in traffic movement and access.

Record of Decision (ROD)

The final decision issued by the lead federal agency regarding an Environmental Impact Statement. For current TTC projects, FHWA would issue a Tier One ROD after the FEIS has ended. This decision could be to approve the preferred corridor alternative identified in the FEIS, select another reasonable corridor alternative as the preferred alternative, select the No Action alternative, or require additional studies. A Tier One ROD would not authorize construction. Rather, if the Tier One decision results in the selection of a preferred alternative, the selected corridor would become the study area for Tier Two environmental processes.

Right of Way

The land (usually a strip) acquired for or devoted to the construction of a transportation facility.

Section of Independent Utility (SIU)

Corridor sections that have logical beginning and end points and represent transportation projects that can be built and function without additional facilities being built at either end.

Tier One

First phase of the two-phased environmental process used for both TTC-35 and I-69/TTC. The goal of Tier One is to narrow a broad study area to a preferred corridor alternative based on the following: the Project’s need and purpose; land use, engineering and design; traffic flow analyses; potential impacts on environmental factors (such as wetlands, farmland soils, cultural resources, and socio-economic issues); and input received from public/agency meetings and comments. If FHWA selects a preferred corridor alternative during Tier One, the selected corridor would become the study area for the second phase (Tier Two) of the environmental process. A Tier One decision does NOT authorize construction.

Tier Two

Second phase of the two-phased environmental process used for both TTC-35 and I-69/TTC. During Tier Two, the preferred corridor alternative selected from Tier One would be studied in more detail. Specific alignments and right of way needs for individual sections of road, rail, and/or utilities would be identified, connections to metro areas would be determined, and potential property impacts would be assessed. Final Tier Two alignment decisions would authorize construction.