Environmental Review Toolkit
NEPA and Project Development

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

8.0 Analysis of Environmental Impacts and Mitigation

8.1 Introduction

The analysis of the environmental consequences, as a result of a proposed project, represents the core of the environmental impact analysis for a project.

Regulations on Analyzing Environmental Effects and Consequences

The CEQ regulations at 40 CFR 1508.8 define “effects” as follows:

Effects includes ecological (such as the effects on natural resources and on the components, structures, and functioning of affected ecosystems), aesthetic, historic, cultural, economic, social, or health, whether direct, indirect, or cumulative. Effects also may include those resulting from actions which may have both beneficial and detrimental effects, even if on balance the agency believes that the effect will be beneficial.

FHWA Technical Advisory T 6640.8A recommends that the section on environmental consequences includes the probable beneficial and adverse social, economic, health, and environmental effects of alternatives under consideration; and describes the measures proposed to mitigate adverse impacts. The information should have sufficient scientific and analytical substance to provide a basis for evaluating the comparative merits of the alternatives.

Safety-focused and general-purpose projects are no different than any other transportation projects with respect to the required analysis of the potential for impact on environmental resources and features. Each project must have a specific and concise purpose and need statement. Creating a comprehensive description of the affected environment, including mapping and quantitative, as well as qualitative data, will be just as important for these safety projects as for any other transportation project.

For both safety-focused and general-purpose projects, direct, indirect, and cumulative environmental impacts related to safety may occur. Direct impacts may include, but not be limited to, the impacts related to the project, such as increased traffic due to capacity increases, facility construction impacts on sensitive environmental resources, or construction impacts on road user safety. These impacts may, in turn, create additional indirect impacts that must be considered. Follow the usual procedures, but keep in mind the following impacts and/or benefits that may be specific to safety-focused projects.

Specific project features that may affect safety include:

  • Design speed;
  • Access management (e.g., driveways);
  • Sight distance;
  • Geometry (e.g., ramp design and configuration, presence or lack of turn lanes);
  • Safety impacts on vulnerable modes or users;
  • Access for emergency vehicles;
  • Signalization;
  • Roadway/roadside features; and
  • Work zone safety during construction.

Construction impacts a common type of safety-related impact cited in environmental documents. Safety impacts also can be considered in the analysis of indirect and cumulative impacts. A third area to consider is the potential to integrate beneficial safety enhancements beyond required mitigation.

8.2 Construction Impacts

Safety-related construction impacts are a common type of safety-related impact requiring mitigation. This issue is particularly significant since approximately 1,000 fatalities occur each year in work zones; moreover, the FHWA’s Work Zone Final Rule (23 CFR 630) requires consideration of work zone safety and mobility issues in project development. Resources are available to assist practitioners in identifying safety countermeasures appropriate for work zones, such as the FHWA-supported National Work Zone Safety Information Clearinghouse (http://www.workzonesafety.org/). The AASHTO NCHRP 500 Series Guide on Reducing Work Zone Collisions is another helpful resource listing proven countermeasures for reducing work zone collisions, such as:

  • Improve maintenance and construction practices;
  • Utilize time-related contract provisions;
  • Use nighttime road work; and
  • Use demand management programs to reduce volumes through work zones.

If work zone impacts are significant, consider a construction stage RSA (see Section 5.0) to identify potential problems in the work zone and means of addressing them.

Although addressing short-term safety issues during construction is very important, it is not a substitute for careful consideration of the long-term safety outcomes of the project itself, which should be evaluated during alternatives analysis.

8.3 Indirect and Cumulative Impacts

Safety-related impacts may be an important component of the analysis of the indirect and cumulative impacts. This is because of the potential for safety impacts to result from the interactions of traffic and land use development over time. For example, new housing, commercial, or industrial developments associated with new transportation facilities could lead to:

  • Increased pedestrian traffic resulting in the need for additional pedestrian safety features around the project site (e.g., high-visibility crosswalks, flashing beacons, pedestrian countdown signals);
  • Increased freight traffic resulting in the need for changes in roadway design to accommodate freight turning movements;
  • Increased numbers of vulnerable road users (e.g., elderly, handicapped) requiring additional safety features, such as oversized or high-visibility road signs for older users, accessible pedestrian signals, etc.; and
  • Expected changes in travel behavior (e.g., more bicycling and walking, increase in transit-dependent population) resulting from expected land use changes, such as densification.

Some of the analytic methods discussed previously, such as safety performance functions provided in the HSM, take into account expected changes in the volumes of personal vehicles and pedestrians in predicting future safety impacts.

The case study below on Health Impact Assessment illustrates an analysis of long-term project impacts on pedestrian safety.

Case Study: Health Impact Assessments

Health Impact Assessments (HIA) are an emerging tool for assessing and capturing all health-related impacts associated with policies or projects, which may include road safety impacts. HIAs are not required as part of NEPA, but have been prepared voluntary, in some cases, as a supplement to environmental documentation.

For example, the Health Impacts Group at the University of California, Berkeley recently evaluated the health impacts of a proposed housing development project in Oakland, California. The Oak-to-9th Health Impact Assessment included the application of a predictive model for measuring the additional pedestrian crashes likely to result from higher vehicle volumes surrounding the future development. This information suggested a need for enhanced mitigation of future pedestrian safety impacts.

Source: UC Berkeley Health Impact Assessment Group, http://sites.google.com/site/ucbhia/projects-and-research.

Since potential safety impacts relate to community context, the assessment of indirect and cumulative impacts also allows for close CSS review when considering potential mitigation and/or avoidance of safety impacts.

8.4 Mitigation and Enhancements

Consider proven safety countermeasures as mitigation for safety-focused projects to integrate safety into NEPA decision-making. Document the safety benefits of proposed features. Refer to Appendix A.4 for resources to help quantify and document the benefits of safety countermeasures.

Practitioners also may go beyond the required mitigation to enhance the safety of the roadway. With safety as a primary Federal goal, the enhancement of safety should be considered as a potential value-added benefit of every project. This statement is particularly true when safety is a state, regional, or local goal.

8.5 Safety After the NEPA Process

Safety improvement does not end with the NEPA process. Safety can be improved and monitored during project construction, maintenance, and operation. Behavioral strategies, such as enforcement and education, can be employed at any time to reduce crashes. The NCHRP 622, Effectiveness of Behavioral Safety Strategies, lists a number of behavioral strategies proven to reduce crashes, such as sobriety checkpoints, bicycle helmet laws, passive alcohol sensors, and many others. Another resource is Countermeasures That Work: A Highway Safety Countermeasure Guide for State Highway Safety Offices. Both resources are described in more detail in Appendix A.4. Finally, programs can be implemented for honoring safety commitments and mitigation strategies from the NEPA process during construction and beyond.

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