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Case Studies

Transportation agencies across the United States are using INVEST to evaluate and improve sustainability within their agency and on their projects.

Case studies focus on the general use of INVEST and its implementation and/or scoring practices. Some focus more on process/application, some focus on a few select criteria, some focus on the overall experience of using INVEST. Case Studies are developed by the agency which submits them, with review and input by FHWA.

Use the map and filters below to find case studies relevant to your projects and/or agency.

Arizona DOT - I-11 Corridor Tier 1 EIS


Lead Agency: Arizona Department of Transportation (ADOT)

INVEST Modules: Project Development and System Planning for States


 Download the Arizona DOT Round 3 Final Report (3,338 kb) and Appendices (18,448 kb)

The Arizona Department of Transportation (ADOT), in partnership with the FHWA has utilized the latest version of INVEST (1.3) on numerous agency projects and programs in varying stages of development to document, explore, and identify sustainability elements of projects for incorporation, as well as provide feedback on the current INVEST 1.3 version of the tool. The goal of this I-11 INVEST case study is to document the use of INVEST on the three Build Corridor Alternatives currently under study as part of the FHWA and the ADOT Interstate 11 (I-11) Tier 1 Environmental Impact Statement (EIS), and to explore and identify potential ways the INVEST tool can link sustainability and the NEPA process, inform future Tier 2 design efforts, and influence overall ADOT sustainable transportation program implementation processes.

I-11 Tier 1 EIS

The ADOT and FHWA are conducting the environmental review process for the I-11 Corridor from Nogales to Wickenburg, Arizona. An Alternatives Selection Report (ASR) and Tier 1 Environmental Impact Statement (EIS) have been prepared as part of this process in accordance with NEPA and other regulatory requirements.

The study is atypical in that it is a tiered EIS process assessing a corridor of approximately 280-miles. Initially, the ASR assessed a comprehensive range of corridor alternatives through a robust high level evaluation process that used extensive public and agency input, innovative public outreach methods, previous studies, and various topographical, environmental, and other planning information to help identify opportunities and constraints. The study also used Quantm, a specialized program used to design roadway and railway alignments. The software uses topographic information, engineering design criteria, and environmental constrains to generate a list of optimized alignments. These were reduced to a reasonable range and carried forward into the Draft Tier 1 EIS for more detailed environmental review – see the figure below.

I-11 Build Corridor Alternatives

The Tier 1 EIS continues to assess the potential social, economic, and natural environmental impacts of the No Build Alternative and remaining corridor alternatives (i.e., Build Alternatives). In addition to the Tier 1 EIS, a project specific Tier 1 Section 106 Programmatic Agreement has been created to identify a Tier 2 Section 106 process and ensure coordination and compliance for all stages of the EIS. The I-11 Draft Tier 1 Environmental Impact Statement and Preliminary Section 4(f) Evaluation (Draft Tier 1 EIS) was completed and made available for public review and comment on April 5, 2019. Based on the comments received and any additional technical analysis, the study team will prepare a Final Tier 1 EIS, outlining a Preferred Alternative for I-11. A Preferred Corridor Alternative will be identified in the Final Tier 1 EIS in late 2020, that will provide an initial concept for proposed incremental projects within the I- 11 Corridor that could be pursued in the future, following completion of the Tier 1 EIS. A Tier 1 document will not include design details.

Scope of a Tier 1 EIS

A Tier 1 EIS encompasses a programmatic approach for identifying existing and future conditions and evaluating the comprehensive effects of the project on the region. The decision at the end of the Tier 1 EIS process would select a 2,000-foot-wide Build Corridor Alternative that would advance to further design and Tier 2 NEPA analysis or select the No Build Alternative. Tier 2 environmental studies would be required to determine the specific alignment of I-11, including design details, and would evaluate more specific project-level issues, such as individual property impacts and specific mitigation. Tier 2 environmental studies could occur in phases, breaking up the 280-mile long Nogales to Wickenburg corridor into interim projects or shorter segments, as funding becomes available. The figure below provides context to the level of detail in a Tier 1 environmental study.

Tier 1 Environmental Study Level of Detail

INVEST Evaluation

The I-11 Tier 1 EIS corridor alternatives represent the range of viewpoints voiced during the study, from supporting the development of a mostly new corridor (Green) to using the existing corridors as much as possible (Orange), and a mix of the two (Purple). INVEST was used for this project to qualitatively assess the three Build Corridor Alternatives and present their scorings in this INVEST case study using the Project Development (PD) Module and the System Planning for States (SPS) module for purposes of linking NEPA and planning studies to incorporate sustainability into the long range project development process. The SPS is traditionally the first step in the lifecycle of a transportation project, and the module includes criteria to self-evaluate an agency's system-level planning and programming policies, processes, procedures and practices. The SPS module in the current INVEST tool includes a total of seventeen (17) criteria that are generally organized from system analysis to corridor wide metropolitan planning programs. PD is traditionally the second step in the lifecycle of a transportation project, where specific projects are planned, designed, and constructed. The PD module in the current INVEST tool includes a total of thirty-three (33) criteria that are generally organized from planning to design to construction. The PD criteria are further organized into seven (7) scorecards for the evaluation of projects. The scorecards are designed to identify applicable criteria based on the project type (paving, small/spot improvements, new facility/corridor project) and location (urban/rural). Six (6) of these scorecards pre-identify criteria that are most likely to be applicable for the project type and location.

Because the study is 280-mile in length, the corridor alternatives were assessed using the PD – Urban Extended scorecard, comprised of thirty-three (33) criteria, defined as a new roadway facility; structure projects where nothing of its type currently exists; and major reconstruction projects that add travel lanes to an existing roadway or bridge. Additionally, this evaluation also included SPS that considers regional evaluations for economics, social, multimodal planning, and other regional planning considerations. Combining the criteria of these two modules for this case study will help further understand the linkages that can be made to NEPA planning, project development, and sustainability.

In addition to the PD – SPS criteria, the I-11 Tier 1 EIS also completed innovative and “above and beyond” practices that could be identified as Innovative Criteria. As described by the FHWA INVEST tool, the Innovative Criteria allows sustainable innovations and emerging technologies to be addressed in their projects or programs evaluation that are not represented in INVEST in order to earn points for these innovations. For the purposes of this case study evaluation, the following Innovative Criteria are identified:

  • SPR-IN-01 – Use of Emerging Technology for Alternatives Analysis (Quantm): Because of the high level analysis needed at the Tier 1 level, an innovative GIS program was used to design roadway and railway alignments. The software uses topographic information, engineering design criteria, and environmental constrains to generate a list of optimized alignments. This helped refined a range of reasonable alternatives at this Tier 1 high level with consideration from all public, agency, and tribal stakeholders.
  • SPR-IN-02 – Above and Beyond Public Input with Udall Foundation Efforts: The ADOT and FHWA engaged with the public in Southern Arizona in an additional effort to seek input on the Tier 1 effort. This coordination effort was undertaken with the study team and the US Institute for Environmental Conflict Resolution (Udall Foundation). A series of workshops and meetings were had to discuss the Tier 1 study and valuable input was provided to the study team for incorporation into the EIS.
  • SPR-IN-03 – Above and Beyond Section 106 Programmatic Agreement & NEPA Innovative Process for Tier 1 Studies: Because the future of Tier 2 studies is unknown and not programmed or funded, the ADOT and FHWA sought out an innovative way to ensure compliance with Section 106 and the National Historic Preservation Act through the use of a project specific Tier 1 Programmatic Agreement (PA). This PA allowed decisions for the process, implementation, and coordination to be discussed and formally documented in the Tier 1 document for any future Tier 2 projects.

Scoring Summary

The PD Urban Extended and SPS scorecards were use for this effort. All three I-11 Build Corridor Alternatives received the same scoring for the Project Development Module each criterion because the INVEST scorecard is structured based on the process followed, not a comparative evaluation of the results of the process. Therefore, since all three were compared using the same process as part of the I- 11 Tier 1 EIS, this tool does not provide enough detailed differentiation measures to contribute to a decision on a Preferred Alternative, but rather reflects sustainable outcomes and useful considerations for integrating sustainability into Tier 2 NEPA processes. What this alternatives analysis effort did present was how valuable it is to identify where certain criteria would be better addressed and overall act as a sustainable corridor baseline for future phases – EIS Tier 2, design, construction, operating, and maintenance.

In considering opportunities to link sustainability and NEPA through the INVEST tool, the evaluation also used selected System Planning for States criteria, and three additional innovative criteria identified as part of the Tier 1 EIS study. Based on the assessment at this Tier 1 level, each of the three Build Corridor Alternatives scored the same. The three innovative criteria also provided additional potential points for the scoring assessment. This cross-utilization of criteria from different modules allowed for the Tier 1 EIS study to identify the relevant sustainability considerations at this Tier 1 level, and allowed for more flexibility in scoring than was provided in the Project Development module only. What this portion of the effort presented is the need in future INVEST versions to include a new dedicated Corridor Planning and Environmental Study module.

Appendix B of ADOT's Round 3 Final Report includes summary tables presenting information on the criteria, the total scoring achieved, notes on the application of the criteria to the I-11 study effort, and columns denoting which is the most applicable project development phase to consider for each criterion. This is critical for tracking future progress, to be proactive and incorporate sustainability considerations as early in the process as feasible in Tier 2 studies. The hybrid criteria have a total of 299 available points. The scoring effort garnered a total of 111 points. On a percentage basis, this corridor already starts with 37% of the sustainability attributes being considered in the study are deemed a sustainable approach according to INVEST. This forms the sustainable baseline to work from in future phases.

Lessons Learned and Opportunities for Future NEPA Studies

At an early stage in the project development process, it was anticipated that this INVEST case study for I-11 Build Corridor Alternatives would not attain a high level rating based on one chosen module alone. Overall, criteria in Project Development related to design or construction received fewer points, as those project development activities are beyond the scope of this Tier 1 study. Considering this information, the ADOT identified relevant NEPA planning scoring criteria in other modules such as SPS and Innovative Criteria that allowed for a more broad and conceptual INVEST scoring with NEPA and sustainability elements. This flexible approach of multiple criteria and modules allowed for a multi-level evaluation that considered NEPA and sustainability not only in the project development design stage, but also combined the higher level planning and programming considerations that is considered in NEPA as well. 

Utilization of INVEST on a series of planning-level alternatives and NEPA studies would be most beneficial with a flexible criteria approach such as the one used in this case study, since the ADOT has many different studies and evaluations at different levels. Additionally, this high level evaluation could be documented as a way to identify and track the relevant sustainability considerations at each level of evaluation, such as a Tier 1 study and Tier 2 study.

Regardless of the type of planning/environmental review process, revisiting the INVEST criteria at the start of each project phase is ideal to continue to integrate sustainability elements into a project and maintain sight on the goals and potential sustainability solutions.


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