Environmental Review Toolkit
NEPA and Project Development

Integrating Road Safety into NEPA Analysis:
A Primer for Safety and Environmental Professionals

6.0 Alternatives Analysis

6.1 Introduction

This section describes how to integrate safety considerations into the alternatives analysis. The extent to which safety is emphasized in this discussion is a function of whether the project is safety focused or not. For projects where safety is a key component of the project purpose and need statement, each alternative should be evaluated for the degree to which it achieves the desired safety improvement purpose. For general-purpose projects, safety improvement may not be an evaluation criterion for each alternative, or may be weighted differently than for a safety-focused project. However, practitioners can still suggest inclusion of safety features, as appropriate, for the project context.

Regulations on Alternatives Analysis

CEQ NEPA regulations describe the importance of the alternatives analysis: “This section is the heart of the environmental impact statement. Based on the information and analysis presented in the sections on the Affected Environment (Sec. 1502.15) and the Environmental Consequences (Sec. 1502.16), it should present the environmental impacts of the proposal and the alternatives in comparative form, thus, sharply defining the issues and providing a clear basis for choice among options by the decision-maker and the public.”

FHWA Technical Advisory T 6640.8A guidance recommends that the Alternatives Analysis section of environmental documents begin with a concise discussion of how and why the “reasonable alternatives” were developed for detailed study, and explain why other alternatives were eliminated.

6.2 Developing Alternatives

Safety-Focused Projects

For safety-focused projects, develop alternatives that solve a specific safety problem, and do so in close consultation with safety specialists and stakeholders, particularly if their input was not collected or documented during the planning phase. Document all comments received, and use this input to modify alternatives and improve the overall project outcome. Base the development of alternatives on a clear understanding of the safety problem. Specialized tools are available to help identify the safety problem and develop solutions (see Appendix A.4). The HSM is the most recent and comprehensive resource describing the state-of-the-art analytical processes for identifying the causes of crashes and developing solutions. The HSM also provides techniques for evaluating the safety impacts of specific design alternatives on certain types of roads.

As much as possible, consider the full range of possible safety solutions, not only engineering countermeasures, but also operational improvements that benefit safety (improved incident response) and behavioral countermeasures (education and enforcement). The NCHRP 500 Research Reports include a series of more than 20 guidebooks indicating a range of 4E (engineering, enforcement, education, emergency response) countermeasures to address a variety of safety solutions (The NCHRP 500 Series Reports are available at: http://safety.transportation.org/guides.aspx).

Select countermeasures not only for their appropriateness in addressing the identified safety problem, but also their effectiveness. The best countermeasures are those that have been proven to reduce fatalities and serious injuries through rigorous study (see inset box below on proven countermeasures). Appendix A.4 lists additional resources for identifying the effectiveness of different types of safety countermeasures.

Proven Safety Countermeasures

On July 2008, the FHWA issued a guidance memorandum on the consideration and improvement of proven safety countermeasures. The guidance states: “While there is still much work to do on determining the precise effectiveness of some safety countermeasures, we are highly confident that certain processes, infrastructure design techniques, and highway features are effective and should be encouraged whenever Federal funds are used. Safety should be considered at every stage of the project development process. Every investment decision should consider the impact on safety, and every Federally-funded project should include appropriate safety enhancement features.” The document goes on to list nine safety countermeasures that research has proven to be effective in reducing fatalities and injuries, and are specifically encouraged by the FHWA:

  1. Road Safety Audits;
  2. Rumble Strips and Rumble Stripes;
  3. Median Barriers;
  4. Safety Edge;
  5. Roundabouts;
  6. Left- and Right-Turn Lanes at Stop-Controlled Intersections;
  7. Yellow Change Intervals;
  8. Medians and Pedestrian Refuge Areas in Urban and Suburban Areas; and
  9. Walkways.

Source: FHWA Guidance Memorandum on Consideration and Implementation of Proven Safety Countermeasures (http://safety.fhwa.dot.gov/policy/memo071008/).

General Purpose Projects

The safety elements of the alternatives that would be considered for a safety-focused project also may be relevant for general-purpose projects. The difference is that the development of the alternatives will have to balance the degree to which they can satisfy all of the identified transportation problems, not just the safety issues.

Even if a project is not safety focused, consider incorporating safety into the development of alternatives. As described in public outreach, give safety specialists an opportunity to review the project design early on to avoid potentially costly design changes. Even if the project design is acceptable, safety specialists may be able to suggest low-cost safety improvements (For more information on low-cost safety improvements, refer to the following resource: FHWA, 2003. Low Cost Traffic Engineering Improvements – A Primer, http://ops.fhwa.dot.gov/publications/low_cost_traf/low_cost_traf.pdf) that could be added without significant impacts to the project scope, schedule, or cost. They also may be able to suggest systemic features that have been identified for inclusion on the appropriate types of roadways due to their proven safety benefit – shoulder rumble strips on rural roads are one common example. Consider an RSA, discussed in Section 5.0, to obtain input from experts on how to improve the safety of a project alternative in the preliminary design stage.

Case Study: Using Proven Countermeasures

The State Route 502 Corridor-Widening Project in the Seattle, Washington region is an example of the incorporation of proven safety countermeasures into the development of alternatives for a general-purpose project. Section 3 of the Environmental Impact Statement, Comparison of Alternatives, discusses the safety benefits of medians, a proven safety countermeasure. The benefits specific to the project include creating a protected turn lane, eliminating turning movements, and reducing the likelihood of a head-on crash by creating a physical barrier between lanes. See Appendix B for additional details.

6.3 Screening Alternatives

NEPA requires that the potential environmental impacts of each alternative be identified and used in determining which alternatives should be advanced through the NEPA analysis and selection process (as long as they also meet the project purpose and need). The selection of reasonable alternatives should be based on: 1) consideration of alternatives that avoid impacts; 2) consideration of the alternatives that minimize impacts; and 3) consideration of the potential mitigation of impacts of each alternative, all while meeting the project purpose and need.

Safety-Focused Projects

A comprehensive stakeholder involvement process is likely to generate a range of alternatives that must be reduced to a smaller set of reasonable alternatives for detailed analysis. A first level of evaluation can be conducted to eliminate alternatives that clearly do not meet the project purpose and need. Further screening may include: 1) the degree to which the alternative solves the problem; 2) compatibility with existing or planned transportation systems; and 3) compatibility with local and/or community goals and objectives.

For projects where safety is a key component of the purpose and need, screen the alternatives with respect to their relative safety benefit (typically defined as the degree to which the project would reduce crashes, fatalities, and/or serious injuries).

Rigorous analysis may not be feasible in all cases, but some assessment of likely safety performance should be included, such as empirical evidence demonstrating the effectiveness of safety features in each alternative compared to a No-build alterative (which presumes none of the alternatives is constructed). The HSM provides specific guidance regarding how to estimate future collisions on certain facility types with and without safety improvements. The basic approach is to apply a safety performance function, which is an equation that predicts changes in collisions as a function of changes in exposure (e.g., volumes of vehicles, bicyclists, pedestrians) to future crash outcomes. This will allow the estimation of future safety conditions for a No-build alternative. Then, practitioners can identify the safety improvements associated with each “build” alternative, and calculate their expected impact on future collisions.

The effectiveness of safety improvements is typically expressed through crash reduction factors, which represent the expected percentage reduction in crashes from countermeasures. The HSM provides the best available crash reduction factors and tools for estimating the potential effects of transportation decisions. The FHWA’s Crash Modification Factors Clearinghouse contains a more comprehensive inventory of all available crash reduction factors, including a star rating to indicate their quality.

As a general rule, use research and analysis to demonstrate the benefits of proposed safety features. If the information is unavailable, a safety benefit cannot be assumed. Adherence to the latest design standards is not sufficient as evidence of a safety benefit. Numerous publications, software, and other resources identified in Appendix A.4 are available to help define the safety benefit of features proposed for various alternatives. For example, the Safety Analyst tool and the Interactive Highway Design Model both can be used to predict future collisions with and without safety countermeasures.

General-Purpose Projects

Ideally, all project alternatives would be designed to be safe and practical, regardless of whether the project was safety focused. In most cases, providing the safest possible design is compatible with other project objectives. However, in some cases, tradeoffs between safety and other objectives (e.g., mobility) arise, particularly in the context of general-purpose projects. The project purpose and need statement should serve as the primary guidance document in deciding how best to balance safety and mobility objectives through the project alternatives. The CSS approach discussed previously also can be useful. It suggests practitioners balance any competing priorities by fully considering the context of the project, including the character of the local community and the desires of community members.

Case Study: Analyzing Safety in Alternatives Analysis

The Town of Eagle, Colorado recently prepared an Environmental Assessment for the future East Eagle Interchange project. This assessment identified the Preferred Alternative that would best meet the need to improve the operational and safety aspects of the transportation network. The study used crash data to demonstrate that safety problems would persist and crashes would increase if no action was taken to improve the roadways in the study area. The study also included the use of a safety performance function to estimate future crash rates of the project alternatives, and to inform the selection of countermeasures. The Town also created a Project Working Group, which developed a five-step process to identify and evaluate the alternatives. Throughout this process, safety elements played a prominent role in goal setting, evaluation, and eventual selection of the Preferred Alternative. Appendix B.1 provides additional detail on this case study.

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