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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 - Sonoran Corridor Study

In February 2017, the Federal Highway Administration (FHWA) and Arizona Department of Transportation (ADOT) initiated an environmental review process for the Sonoran Corridor, which would connect Interstate 19 and Interstate 10 south of the Tucson International Airport. A Corridor Selection Report (CSR) and Tier 1 Environmental Impact Statement (EIS) were prepared as part of this process in accordance with the National Environmental Policy Act (NEPA) and other regulatory requirements. The project objective is to identify an appropriate and approximate 2000-foot corridor for a future roadway that would be subject to a detailed design and a Tier 2 environmental review to identify a final roadway alignment and necessary project mitigation treatments.

Tier 1 Sonoran Corridor "Range of Reasonable Alternatives"

At the direction of ADOT, this case study evaluates processes and methodologies used for development of the Sonoran Corridor Tier 1 EIS compared to INVEST guiding principles. ADOT will also use this specific analysis of INVEST related to the Sonoran Corridor Tier 1 EIS to determine the suitability of applying INVEST at varying stages of project development for future transportation projects in Arizona. Specifically, ADOT would like to incorporate the INVEST perspective into early planning and development efforts to position projects to address critical triple bottom line elements as the project is defined to avoid conflicts in later phases of work.

To assess the Sonoran Corridor Tier 1 EIS process with INVEST principles, answers to the following questions were identified for each of the INVEST System Planning Criteria for Regions, and Project Development Rural Basic Criteria:

  1. Based on the criteria description and what is available in the Sonoran corridor documents now, do these criteria apply? If so, how? If not, why not?

  2. What elements of the criteria are most applicable at a Tier 1 level of analysis and how do these criteria score for the project

  3. Are there elements of the criteria that would be applicable as the project progresses through NEPA development? What are those and why?

  4. Of the environmental resource criteria (PD-02,07,08,09,15,16,18,30), which of these would help to either inform or improve the assessment of project impacts and environmental benefit?

  5. What are the recommendations for agencies and FHWA to incorporate the planning and project development elements of the INVEST tool into NEPA studies and evaluations?

In addition to being asked to evaluate the Sonoran Corridor Tier 1 EIS with the Project Delivery module, several Planning for Regions (SPR) criteria were considered for this case study for their applicability to the high level NEPA planning process and Tier 1 effort. As described in the INVEST description, the SPR criteria are usually geared towards a planning process for Metropolitan Planning Organizations, Councils of Governments, or other planning organizations that perform landscape-scale planning for a metropolitan area as well as some fundamental activities that State DOTs do as part of their planning process and engagement with the public around regional planning.

A Tier 1 NEPA document is usually generated after a regional planning effort has occurred and does not usually consider the full range of considerations that a planning organization or council of government must evaluate in their long range plans or other planning efforts; therefore, the Tier 1 Sonoran Corridor Alternatives were evaluated against the SPR criteria that were most applicable to related to the high level NEPA planning process. This evaluation of SPR criteria allowed for an evaluation of criteria that were considered and undertaken in this high level NEPA process, and provided insight as to if these results were reflected in the Tier 1 document. This assessment was conducted at a very high level given the nature of the study, but this could be a valuable review to link the planning, NEPA process, and the INVEST tool. This case study will help define sustainability expectations and potential improvements for further Tier 2 studies, explore the potential linkages between NEPA studies and the INVEST tool, and allow ADOT to evaluate the range of capabilities that is available at a Tier 1 level, as well as other criteria that can be identified for further evaluation in future studies at Tier 2.

Sonoran Corridor Tier 1 Level of Study

The criteria addressed in this assessment reflect the information resulting from the current level of analysis completed for the Tier 1 EIS for the Sonoran Corridor. Other criteria that were not addressed require more detail than is available at a high level NEPA study phase. As such detail is generated during the Tier 2 or later phases of investigation, a more complete INVEST assessment is likely possible, and those opportunities have been noted in each of the pertinent criterion descriptions.

System Planning Assessment

INVEST considers the earliest stages of a transportation through the System Planning for States (SPS) or System Planning for Regions (SPR) criteria, which apply the same criteria at either a state or regional level depending on the geographical extent of the proposed project. SPR was used to analyze and assess the system-wide network the Sonoran Corridor would be a part of to identify projects that would improve the safety, capacity, access, operations, or other key features of the system.

Each of the relevant SPR criteria listed below is followed by a total point score. The scores for this Tier 1 analysis represent the overall Corridor Selection and Evaluation process, not individual Sonoran Corridor alternatives. For the full SPR scoring, see Appendix B of ADOT's Round 3 Final Report.

SPR-03 Integrated Planning: (Social) - 12 points

The Sonoran Corridor study coordinated with a diverse group of agencies and communities during the preparation of the Tier 1 EIS to develop an agreed-upon reasonable range of corridor alternatives according to the interplaying goals of the region. Members of the community were notified about the study process and public meetings via newspaper advertisements, the study website, email blasts, social media, news releases, media interviews, and blog posts. Agencies and tribal communities were invited by FHWA and ADOT by letter. Spanish translations of meeting materials were also available. The Need and Purpose Statement, the Corridor Selection Report, and the Tier 1 EIS all considered written and oral comments received from agencies and Tribal communities during scoping. The comments and information received were taken into consideration in developing the 2,000-foot-wide corridor alternatives. The Tier 1 EIS process also included agency and outreach coordination milestones to assess the performance of the study’s public engagement.

If one of the corridor alternatives is selected and demand is warranted, green technologies could be evaluated during development of the Tier 2 NEPA process, demonstrating innovations that promote sustainability, improve water quality, reduce storm water runoff, save energy, and maintain air quality, while providing educational opportunities and stimulating business and job growth. The document doesn’t have at least one “year after” goal established using performance measures, as this would be premature for a Tier 1 EIS; therefore, SPR-03.4c does not apply at this current level of evaluation.

In Tier 2, a more complete level of analysis would be undertaken with a more specific roadway alignment and the associated effects for which appropriate avoidance and mitigation could be defined. Depending on the extent of the Tier 2 effort (i.e., phasing and configuration), it could include an analysis of the most sustainable practices and a “year after” assessment, which is the SPR-03.4c criteria, and others such as SPR-03.4a and SPR-0.3.4b. In Tier 2 studies, the new facility would very likely begin to influence the regional plan and the way the project would be brought to fruition. With that added understanding, SPR-01 (Economic Development and Land Use) and SPR-02 (Natural Environment), for example, could also be measured for their contribution to sustainability and benefit.

SPR-05 Access and Affordability - 7 points

The planning documents completed for the Sonoran Corridor Tier 1 EIS evaluated the access issues of the area that included access to commercial centers, jobs, and other civic activity centers that were compiled from the stakeholder and public outreach meeting. The Sonoran Corridor is intended to improve access and mobility of the public to the transportation system, eliminate out-of-direction travel, and open new areas for employment opportunities. Shorter commute times for middle- and low-income workers who are employed at TUS and other area employers would also be a benefit of the Sonoran Corridor. Corridor alternatives that performed better under these metrics were more promising to continue through the screening process into the EIS phase.

The Tier 1 EIS commits to a multimodal analysis, and provides some documentation regarding multiple modes as appropriate at this stage. The Need and Purpose sets as one of the project objectives the ability to establish or improve access to existing and planned activity centers. The Tier 1 EIS also identifies disadvantaged populations and, at a high level, how the corridor alternatives under consideration would affect them. Further refinement to modal types and design elements, and the effects on population characteristics and economic centers based on preliminary design information for the corridor, will be evaluated in Tier 2 documents. In Tier 2, additional criteria such as SPR-05.3 could be considered as a sustainable project development goal to encourage monitoring of sustainable outcomes and transportation planning.

SPR-07 Multimodal Transportation and Public Health - 8 points

The 2045 Regional Mobility and Accessibility Plan (RMAP) is a regional transportation plan adopted by the Pima Association of Governments (PAG) in 2016. The plan includes active transportation goals and future planned multimodal infrastructure to promote public health and awareness. Also included in the 2045 RMAP is a multimodal network, which the study team used to analyze the feasibility of the Sonoran Corridor to improve the connectivity of the region. The study also considered opportunities for multimodal enhancements to the Sonoran Corridor as one of its criteria in the alternatives analysis of the Corridor Selection Report. Improvements to public health generally come with multimodal enhancements to an active transportation mode. The study stakeholders and the public were presented the multimodal screening criterion during the public outreach meetings.

While multimodal opportunities have been identified in the Tier 1 EIS, no specific modal options have been singled out beyond the corridor needed to expand regional travel options. Hence, the health benefits of corridor options will rely on information not yet available. The selected corridor is intended to accommodate all appropriate modes such as automobiles, trucks, bicycles, utilities, rail, etc., as appropriate. The specific features and implementation timing of individual elements will be further evaluated during Tier 2 analyses built around a specific alignment, which will afford a more complete assessment of SPR-07, as well as point for other criteria such as SPR-07.3 and SPR-07.4, which consist of monitoring progress and sustainability efforts as it relates to public health and multimodal transportation.

SPR-08 Freight and Goods Access & Mobility - 8 points

The stated goals of the corridor alternatives in the Tier 1 EIS are to improve passenger and freight travel within the study area. This improves mobility for corridor residents, employees, visitors, manufacturers, growers, shippers, etc., by reducing congestion and improving Level of Service (LOS). The process included engaging agencies, Tribal communities, and community organizations in the scoping process. Participants attended agency scoping meetings held at the PAG offices in Tucson, AZ. Within the Tier 1 EIS, a freight evaluation was performed through documentation of annualized truck trips and potential reductions in truck volumes on existing routes as a result of the Sonoran Corridor.

The Sonoran Corridor is proposed to explicitly address improving goods movements, and the Need and Purpose for the corridor reflects the demand for freight movements through and to the greater Tucson area. The Tier 1 EIS contained freight mobility goals, and stakeholders from state and local communities. Commercial freight shippers were also consulted as part of the development of that plan. Performance measures were developed for freight access, and ADOT and the planning agencies monitor freight mobility measures such as delay, travel time, and state freight movement goals.

As mentioned, a goal of the Sonoran Corridor is to improve freight connectivity between trip generators and intermodal terminals such that improvements in air quality and reduction in natural resource impacts can be achieved. The plans for the corridor have mobility measures for freight, and the criteria for selecting the corridors that appear in the Tier 1 EIS reflect those measures, such as reliability, travel time, through-put, or volumes. The findings of the Tier 1 analysis will be refined with more detailed information in Tier 2 analyses to provide a more complete understanding of freight movement, which could include technology enhancements, reliability improvements and travel time and travel cost reductions. In Tier 2, additional efforts could be considered that were outlined in this category, such as evaluation of freight access (SPR-08.4a), and monitoring sustainable outcomes of consideration of these resources for the project.

SPR-09 Travel Demand Management - 2 points

ADOT and PAG have developed Travel Demand Management (TDM) goals and measures. The Sonoran Corridor is being studied to achieve those goals and measures, as outlined in the Need and Purpose of the Sonoran Corridor Tier 1 EIS. The study also intends to evaluate the inclusion of multimodal features, and while it does not set up a TDM program, it will not hinder the deployment (or even enhance TDM network elements) of the region’s TDM program. The Sonoran Corridor does not have specific TDM measures applied to it, as those are better evaluated on a network basis when more detail is known about the corridor alignment and its connections to the local roadway system, such as in the process of developing the Tier 2 level analyses for the project. This Tier 1 EIS, therefore, is unable to and does not propose to monitor TDM efforts. However, ADOT and PAG will incorporate the Sonoran Corridor concept into their TDM planning and implementation in future stages of the project.

SPR-13 Analysis Methods - 3 points

The most recently available quality transportation and socio-economic data for travel demand models from PAG and ADOT were utilized in the Corridor Selection Report. The PAG data and model are in an update cycle for adoption later in 2020. For the Sonoran Corridor, the data were of sufficient quality and quantity to make consistent decisions for alternative screening and impact analysis of the corridors addressed in the Tier 1 EIS. The data are on a 5-year update cycle through PAG’s regional transportation update of the Regional Mobility and Accessibility Plan (RMAP). The current update is to be completed in 2020. ADOT has a planning and funding program to continue the development of the needed technical resources and data that will be evaluated again in the Tier 2 NEPA document. The data and analysis methods of the transportation planning elements for the Tier 1 document were peer reviewed by members of the team to ensure quality application of the transportation model outputs and the development of the performance of the different corridor alternatives. This planning criterion is very focused on the activities within the planning process and, therefore, is not easily applied to this Tier 1 EIS. The updated socio-economic information and corridor details will be available to the Tier 2 analyses, which will provide a more current assessment of conditions and allow more rigorous forecasting using methods similar to those used in the Tier 1 studies. In addition to more detailed information provided in Tier 2, future analysis done could have more detailed review processes from external stakeholders, as defined in SPR-13.3.

SPR-14 Transportation Systems Management and Operations - 0 points (not applicable in Tier 1)

This criterion is not applicable to a Tier 1 EIS because TSMO infrastructure is not addressed at this stage of the NEPA process. Since the result of the Sonoran Corridor Tier 1 EIS is identification of a preferred 2,000-foot-wide corridor for future transportation use, no potential infrastructure is at the design or engineering stages. For this reason, the transportation systems management and operations criterion does not apply.

Evaluating criteria according to transportation systems management and operations would most likely be appropriate at a cursory level in the Tier 2 analysis, an anticipated next step in the NEPA process. The Tier 2 process assesses preliminary design and engineering concepts, resulting in a final alignment for the new transportation facility, enabling permitting for the selected alignment. A more complete TSMO analysis requires a final design of the future corridor facilities, but in Tier 2 studies could incorporate this analysis to consider a range of ADOT TSMO strategies, goals, and objectives. Additionally, this could be considered as an additional effort for consideration in Tier 2 for design and sustainability performance measures, as outlined in SPR 14.5 and SPR 14.6.

SPR-16 Infrastructure Resiliency - 0 points (not applicable in Tier 1)

This criterion is not applicable to a Tier 1 EIS because infrastructure adaptation and resiliency could not be addressed without a selected transportation facility design. Since the result of the Sonoran Corridor Tier 1 EIS is identification of a 2,000-foot-wide preferred corridor for future transportation use, no potential infrastructure is at the design or engineering stages. For this reason, evaluating the selection infrastructure resiliency criterion does not apply.

Evaluating criteria related to infrastructure resiliency will most likely be appropriate in the Tier 2 environmental document, the next step in the NEPA process. The Tier 2 process assesses preliminary design and engineering concepts, resulting in a final alignment for the new transportation facility, enabling permitting for the selected alignment. A more complete resiliency analysis requires a final design of the future transportation facilities. However, there are opportunities identified that could be evaluated in Tier 2 studies, such as the coordination with agencies and stakeholder requirements at a planning level that the SPR 16.1 and SPR 16.2 identify as necessary for this effort. In addition, the Tier 2 design process can include larger planning efforts to evaluate infrastructure risk from a regional standpoint with this project, as described in the criteria SPR 16.3. The adoption of these strategies in Tier 2 would lend the NEPA study to a full life cycle evaluation that incorporates sustainability from a long term engineering design perspective.

SPR-17 Planning and Environmental Linkages - 11 points

The Sonoran Corridor Tier 1 EIS set goals and objectives for integrating system planning as part of the Need and Purpose statement required by the NEPA process. Through coordination with the stakeholders, cooperating agencies, and the public, the study documents the relationships between system planning and NEPA, including an executive level of commitment. The analysis conducted by agencies and the consultant team demonstrate that NEPA practitioners were consulted and that NEPA principles and methods were applied during the extent of system planning that occurs in a Tier 1 EIS. In this evaluation, the Tier 1 EIS process meets some or all of the requirements SPR-17.1 through SPR-17.5, excluding SPR-17.6, and therefore, the Sonoran Corridor Tier 1 EIS receives 11 points out of a possible 15. Tier 2 efforts would allow more complete consideration of sustainability principles targeted to specific features of the project once a preliminary design is available, such as monitoring and evaluating sustainable outcomes as indicated in the SPR 17.5 and SPR 17.6 criteria.

Project Development Assessment Using the Rural Extended Scorecard

INVEST’s Project Development (PD) module includes a total of 33 criteria that are intended to be applied to specific projects as they are planned, designed, and constructed. These criteria have been organized into seven “scorecards,” each a subset of the 33 PD criteria, tailored to apply to different projects based on their type and location. The best fit for the characteristics of the Sonoran Corridor study was the Extended Rural scorecard, designed to assess “rural projects for 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.” This is due to the fact that the Sonoran Corridor study area is not within a major metropolitan area or highly populated region as it exists today. All of the evaluation criteria in the INVEST PD Rural Extended scorecard were considered in this assessment, but because a Tier 1 EIS examines potential environmental effects at a preliminary stage of development and the INVEST PD criteria are geared more toward scoring project-specific design and construction elements, some criteria did not apply to this Tier 1 study, and are considered more applicable for Tier 2 incorporation. Those PD criteria that achieved a score of 1 or higher are summarized individually below, while those that could not be scored at the Tier 1 EIS level of development are listed under a single summary statement and in Appendix B of ADOT's Round 3 Final Report. For the full PD scoring, see Appendix B.

PD-01 Economic Analyses - 2 points

The Sonoran Corridor Tier 1 EIS completed a high-level benefit/cost analysis (BCA) that using the PRISM model. This model was applied to develop costs for capital, operating, and maintenance of a potential transportation facility, making some assumptions about the specifics in the 2,000-ft. corridor that included preliminary engineering concepts to determine some level of feasibility. Since only a BCA was conducted as part of the Sonoran Corridor Tier 1 EIS, the project receives 2 points.

PD-02 Lifecycle Cost Analyses - 1 point

The Sonoran Corridor Tier 1 EIS completed a high-level benefit/cost analysis that used a lifecycle approach to costs. The PRISM model was applied to develop costs for capital, operating, and maintenance of a potential transportation facility, making some assumptions about the specifics in the 2,000-foot-wide corridor that included preliminary engineering concepts to determine some level of feasibility. This will all have to be updated during the Tier 2 process after the initial design and engineering of the transportation facility is undertaken. The Tier 2 process will assess early design and engineering concepts, resulting in a final alignment for the new transportation facility and enabling permitting for the selected alignment. The initial design and engineering of the transportation facility undertaken in a Tier 2 document would benefit from evaluating selection methodology using the PD-02 LCCA criterion. Since the PRISM model conducted a high-level LCCA on the major features of a potential transportation facility, at least 1 point is achieved.

PD-03 Context Sensitive Project Development - 5 points

The Sonoran Corridor Tier 1 EIS satisfied requirements PD-03.1-4 of the Context Sensitive Project Development criterion. While not officially outlining it, the study used a variant of the six-step process for CSS-based Project Development by defining the Need and Purpose, developing the evaluation methodology, and evaluating alternatives through a screening process. The study also deployed a multi-disciplinary team of planners, engineers, environmental experts, economists, data analysts, and public involvement specialists. The Sonoran Corridor Tier 1 EIS also created “public champions” by engaging members of the public from the affected community to build support for the project. Finally, visualizations were leveraged throughout the study’s analysis and at public meetings. Requirements PD-03.5-8 of this criterion are more applicable to a Tier 2 analysis, the next step in the NEPA process due to the need for final design information for consideration and coordination with project teams.

The Tier 2 process will assess early design and engineering concepts, resulting in a final alignment for the new transportation facility, enabling permitting for the selected alignment. The initial design and engineering of the transportation facility undertaken in a Tier 2 NEPA document would benefit from a complete evaluation of its selection methodology using the PD-03 Context Sensitive Project Development criterion.

PD-04 Highway and Traffic Safety - 3 points

Highway and traffic safety was one of the many factors instigating the Sonoran Corridor according to the Need and Purpose Statement. At the public meetings, members of the community were  presented these aspects of the Sonoran Corridor Tier 1 EIS. However, a number of the criteria apply to the final design and construction of the facility, which at the Tier 1 stage, has not been developed, so those criteria would be more applicable for Tier 2. These include:

  • PD-04.3a, Establish the project type;

  • PD-04.3c, Develop and evaluate the project design and/or operational alternatives through substantive safety performance assessment in preliminary and final design details, including the safety impact of any design exception in the project, and identifying potential mitigating actions to improve safety performance; and

  • PD—04.4, Evaluate safety performance of the project after implementation.

PD-05 Educational Outreach - 2 points

Throughout the development of the Sonoran Corridor Tier 1 EIS, professional technical presentations were given to the public in June 2017, September 2018, and March 2019 that highlighted the need and purpose, the evaluation criteria, and the project benefits. A study website was also maintained that included information on the study and its development, while also providing a forum for the public to submit comments and feedback. Since a minimum of two different educational elements from table PD-05.1.A were satisfied, the Sonoran Corridor Tier 1 EIS was assigned 2 points of 2 possible.

PD-07 Habitat Restoration - 2 points

In selecting the three corridor alternatives for the Sonoran Corridor Tier 1 EIS, the comprehensive set of corridors underwent an evaluation of several environmental and ecological factors focused on minimizing impacts to the natural environment including Wetlands/ Floodplains/Rivers/Washes/Arroyos, Wildlife Corridors, and Biological Resources. Since the selected corridor alternative in the Tier 1 EIS will only have been evaluated for minimizing impacts on the surrounding natural resources and environment, the Sonoran Corridor Tier 1 EIS receives 2 points out of 7 possible, satisfying 07.1a and 07.3a. The initial design and engineering of the transportation facility undertaken in a Tier 2 NEPA process could also benefit from evaluating its selection methodology using the full PD-07 Habitat Restoration criterion. Specifics concerning potential habitat destruction and opportunities for restoration can inform the design of the specific highway alignment at the Tier 2 stage.

PD-15 Historic, Archaeological, and Cultural Preservation - 1 point

Prerequisite PD-15.1P and PD-15.3P are satisfied since there are resources or sites within the study area that have been identified as being eligible under the NHRP or by state, local, or Tribal HPOs and the community recognizes as having historic, cultural, and/or archaeological significance, therefore criterion PD-15 applies in analyzing the Sonoran Corridor Tier 1 EIS. The corridor alternatives analyzed in the EIS were evaluated based on their avoiding impact to cultural/sensitive resources known in the study area. At this point for a Tier 1 EIS, we can say that the study achieves the PD15.1b and 15.1d criteria for avoidance, since the reasonable range of alternatives had the fewest potential historic and archaeological sites of the alternatives considered in the CSR. While the corridor alternatives that advanced to the Tier 1 EIS contain a minimal number of cultural sites and resources within their 2,000-foot corridor swath, the final transportation facility alignment chosen in the Tier 2 document should have more design options to avoid these sites and resources. Criteria PD-12.1b and 12.1c should be considered at that point, along with the others. The initial design and engineering of the transportation facility undertaken in a Tier 2 study would benefit from evaluating its selection methodology using the PD-15 Historic, Archaeological, and Cultural Preservation criterion. Specifics concerning potential effects to cultural resources and opportunities for preservation can inform the design of the specific highway alignment at the Tier 2 stage.

PD-16 Scenic, Natural, or Recreational Qualities - 1 point

The Sonoran Corridor Tier 1 EIS only identifies one recreational resource that is directly affected by all of the alternatives, which is the Juan Bautista de Anza National Historic Trail. There is currently no recreational trail within any of the affected portions of the Juan Bautista de Anza National Historic Trail. This has been deemed a Section 4(f) property, and several mitigation strategies are listed in the Tier 1 EIS to minimize any potential impacts from a future transportation facility, including maintaining access to the trail. The Sonoran Corridor study scores 1 point for striving to minimize impacts and providing access to impacted scenic, natural, or recreational qualities.

Evaluating criteria related to maintaining access to scenic, natural, or resource qualities will most likely be appropriate in the Tier 2 environmental document, the next step in the NEPA process. The Tier 2 process assesses early design and engineering concepts, resulting in a final alignment for the new transportation facility, enabling permitting for the selected alignment. The initial design and engineering of the transportation facility undertaken in a Tier 2 study could benefit from evaluating its selection methodology using the PD-16 Scenic, Natural, or Recreational Qualities criterion. Specifics concerning potential impacts on scenic, natural, or recreational resources and opportunities for mitigation can inform the design of the specific highway alignment at the Tier 2 stage.

PD-18 Site Vegetation, Maintenance and Irrigation - 3 points

The Sonoran Corridor Tier 1 EIS states that the ADOT Roadside Development Section will determine if the Arizona Department of Agriculture needs to be informed of the presence of protected native plant species. The Tier 1 EIS also outlines a framework for mitigating noxious and invasive plant species by stating that the ADOT Roadside Development Section would provide special provisions for the control of noxious and invasive plant species during construction of a transportation facility. The EIS also directs that a contractor develop a Noxious and Invasive Plant Species and Control Plan with its construction plan. The Sonoran Corridor receives 3 points for planning to address invasive plant species prevention and the commitment to maintaining native species throughout construction and operation of a future transportation facility. The future Tier 2 document will be able to take advantage of this planning and at the preliminary design stage likely be able to capture all of the criteria points with consideration of additional construction and design activities under PD-18.2.

The criteria listed below were found not to be applicable to a Tier 1 EIS due to the high level preliminary design NEPA stage of the study. Since the result of the Sonoran Corridor Tier 1 EIS is the identification/selection of a 2,000-foot-wide corridor for future transportation use, more design, engineering, and construction would need to take place in Tier 2 to determine the full range of points and applicability of these criteria.

Evaluating the PD criteria listed below will be implemented in Tier 2 analysis studies and the next step in the NEPA process. The Tier 2 process assesses early design and engineering concepts, resulting in a final alignment for the new transportation facility, enabling permitting and construction for the selected alignment. The initial design and engineering of the transportation facility undertaken in a Tier 2 study would benefit from evaluating its selection methodology using the following criteria:

  • PD-06 Tracking Environmental Commitments

  • PD-08 Stormwater Quality and Flow Control

  • PD-09 Ecological Connectivity

  • PD-13 Freight Mobility

  • PD-14 ITS for System Operations

  • PD-17 Energy Efficiency

  • PD-19 Reduce, Reuse, and Repurpose Materials PD-20 Recycle Materials

  • PD-21 Earthwork Balance

  • PD-22 Long-Life Pavement

  • PD-23 Reduced Energy and Emissions in Pavement Materials

  • PD-24 Permeable Pavement

  • PD-25 Construction Environmental Training

  • PD-26 Construction Equipment Emission Reduction

  • PD-28 Construction Quality Control Plan

  • PD-29 Construction Waste Management

  • PD-30 Low Impact Development

  • PD-31 Infrastructure Resiliency Planning and Design

  • PD-32 Light Pollution

INVEST Tier 1 EIS Applicability Summary

The Sonoran Corridor Tier 1 EIS scoring methodology and approach received some INVEST criteria points associated with the corridor selection process, and identified a large range of criteria that can be brought into future Tier 2 analysis. While some criteria had minimal points due to the fact that the INVEST criteria were not directly applicable to the Tier 1 EIS process, this effort showed that at a high level NEPA study phase, opportunities for incorporation of sustainability INVEST criteria generated a total of over 60 points from a range of different modules and INVEST criteria. This overall scoring is only a result of a lack of detailed design information available, as well as the fact that INVEST project development criteria and system planning criteria apply to more detailed design, scoping, and operational considerations. In the Tier 2 NEPA process, there will be opportunities to further incorporate INVEST criteria into the planning of this transportation facility alignment, which will allow for a more quantitative assessment as it relates to the environment, economy, and social considerations identified in the INVEST tools and modules evaluated.

Even at a Tier 1 level NEPA study, a goal for ADOT is to have an awareness of sustainability all phases of design and planning. This INVEST case study considered a variety of criteria in the project development module and the system planning module to help identify the relevant considerations at the NEPA study phase, and to outline follow-up efforts such as Tier 2 analyses or project design and construction elements. There are a variety of outcomes from this case study that can help overall Tier 2 project implementation with respect to the principles of sustainability; for example, planning considerations under the system planning module for criteria such as Planning and Environmental Linkages (SPR-17) and Access and Affordability (SPR-05) were already regarded as highlights at this Tier 1 level of study and were identified as noteworthy criteria to follow up with in later Tier 2 project stages. Although these criteria are normally suited for metropolitan area planning efforts or long range planning, the NEPA study process that was undertaken for the Sonoran Corridor showed that there were relevant planning linkages that could be applied in the INVEST tool to these types of projects as well.

In the future, the INVEST tool, and this case study evaluation that considered a wide range of INVEST criteria could help in clearly defining the relative environmental, social, and economic considerations that can be defined at a high level NEPA planning stage for other studies, and can influence and improve the methodology overall for these ADOT studies as well. Some of the criteria addressed in this report demonstrate that, at a high level, they can be measured from the data developed in the Tier 1 effort. It would be helpful if projects teams in the future were able to use the INVEST tool in a flexible manner to develop a list of criteria around elements that can be assessed with the types of information available from a Tier 1 study, such as SPR-03, 05, 07, 08, 09, 13, and 17, and the project development criteria scored for this INVEST case study. In addition, it would be beneficial if the current INVEST modules related to system planning for regions and states and the project development module could be expanded to incorporate more elements of criteria specific to high level NEPA planning framework to assist states with considering sustainability at this preliminary design stage as well.

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