Conclusions and Recommendations
On the basis of its investigations and deliberations, the committee reached the following conclusions and recommendations.
CONCLUSION: Most road projects today involve modifications to existing roadways, and the planning, operation, and maintenance of such projects often are opportunities for improving ecological conditions. A growing body of information describes such practices for improving aquatic and terrestrial habitats.
Recommendation: The many opportunities that arise for mitigating or reducing adverse environmental impacts in modifications and repairs to existing roads should not be overlooked. Environmental considerations should be included when plans are made to repair or modify existing roads, as well as when plans are made to build new roads.
CONCLUSION: Planning boundaries for roads and assessing associated environmental effects are often based on socioeconomic considerations, resulting in a mismatch between planning scales and spatial scales at which ecological systems operate. In part, this mismatch results because there are few legal incentives or disincentives to consider environmental effects beyond political jurisdictions, and thus decision making remains primarily local. The ecological effects of roads are typically much larger than the road itself, and they often extend beyond regional planning domains.
Scientific literature on ecological effects of roads generally addresses local-to-intermediate scales, and many of those effects are well
documented. However, there are few integrative or large-scale studies. Sometimes the appropriate spatial scale for ecological research is not known in advance, and in that case, some ecological effects of roads may go undetected if an inappropriate scale is chosen. Few studies have addressed the complex nature of the ecological effects of roads, and the studies that have done so were often based on small sampling periods and insufficient sampling of the range of variability in ecological systems.
Recommendation: Research on the ecological effects of roads should be multiscale and designed with reference to ecological conditions and appropriate levels of organization (such as genetics, species and populations, communities, and ecological systems).
Recommendation: Additional research is needed on the long-term and large-scale ecological effects of roads (such as watersheds, ecoregions, and species’ ranges). Research should focus on increasing the understanding of cross-scale interactions.
Recommendation: More opportunities should be created to integrate research on road ecology into long-term ecological studies by using long-term ecological research sites and considering the need for new ones.
Recommendation: Ecological assessments for transportation projects should be conducted at different time scales to address impacts on key ecological system processes and structures. A broader set of robust ecological indicators should be developed to evaluate long-term and broad-scale changes in ecological conditions.
CONCLUSION: The assessment of the cumulative impacts of road construction and use is seldom adequate. Although many laws, regulations, and policies require some consideration of ecological effects of transportation activities, such as road construction, the legal structure leaves substantial gaps in the requirements. Impacts on certain resources are typically authorized through permits. Permitting programs usually consider only direct impacts of road construction and use on a protected resource, even though indirect or cumulative effects can be substantial (for example, effects on food web components). The incremental effects of many impacts over time could be significant to such resources as wetlands or wildlife.
Recommendation: More attention should be devoted to predicting, planning, monitoring, and assessing the cumulative impacts of roads. In some cases, the appropriate spatial scale for the assessment will cross state boundaries, and especially in those cases, collaboration and cooperation among state agencies would be helpful.
CONCLUSION: The methods and data used for environmental assessment are insufficient to meet the objectives of rapid assessment, and there are no national standards for data collection. However, tools for in situ monitoring, remotely sensed monitoring, data compilation, analysis, and modeling are continually being improved, and because of advances in computer technology, practitioners have quick access to the tools. The new and improved tools now allow for substantial improvements in environmental assessment.
Recommendation: Improvements are needed in assessment methods and data, including spatially explicit models. A checklist addressing potential impacts should be adapted that can be used for rapid assessment. Such a checklist would focus attention on places and issues of greatest concern. A national effort is needed to develop standards for data collection. A set of rapid screening and assessment methods for environmental impacts of transportation and a national ecological database based on the geographic information system (GIS) and supported by multiple agencies should be developed and maintained for ecological effects assessment and ecological system management across all local, state, and national transportation, regulatory, and resource agencies. Standard GIS data on road networks (for example, TIGER) could be interfaced with data models (for example, UNETRANS) to further advance the assessment of ecological impacts of roads.
Recommendation: The committee recommends a new conceptual framework for improving integration of ecological considerations into transportation planning. A key element of this framework is the integration of ecological goals and performance indicators with transportation goals and performance indicators.
Recommendation: Improved models and modeling approaches should be developed not only to predict how roads will affect environmental conditions but also to improve communication in the technical community, to resolve alternative hypotheses, to highlight and evaluate
data and environmental monitoring, and to provide guidance for future environmental management.
CONCLUSION: With the exception of certain legally specified ecological resources, such as endangered or threatened species and protected wetlands, there is no social or scientific consensus on which ecological resources affected by roads should be given priority attention. In addition, current planning assessments that focus on transportation needs rarely integrate other land-management objectives in their assessments.
Recommendation: A process should be established to identify and evaluate ecological assets that warrant greater protection. This process would require consideration not only of the scientific questions but also of the socioeconomic issues. The Federal Highway Administration should consider amending its technical guidance, policies, and regulations based on the results of such studies.
CONCLUSION: The state transportation project system offers the opportunity to consider ecological concerns at early planning stages. However, planning at spatial and temporal scales larger than those currently considered, generally does not address ecological concerns until later in a project’s development.
Recommendation: Environmental concerns should be integrated into transportation planning early in the planning process, and larger spatial scales and longer time horizons should be considered. Adding these elements would help to streamline the planning process. Metropolitan planning organizations and state departments of transportation should conduct first-level screenings for potential environmental effects before the development of a transportation improvement plan. Transportation planners should consider resource-management plans and other agencies’ (such as the U.S. Corps of Engineers, U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, and National Park Service) environmental plans and policies as part of the planning process. Other agencies should incorporate transportation forecasting into resource planning.
CONCLUSION: Elements of the transportation system, including the types of vehicles and their fuels, will continue to evolve. Changes in traffic volume and road capacity, mostly through widening of roads
rather than construction of new corridors, have smaller but nevertheless important ecological effects compared with the creation of new, paved roads.
Recommendation: Monitoring systems should be developed for the evaluation and assessment of environmental effects resulting from changes in the road system—for example, traffic volume, vehicle mix, structure modifications, and network adjustments. Data from monitoring could then be used to evaluate previous assessments and, over the long term, improve understanding of ecological impacts.
CONCLUSION: Much useful information from research on the ecological effects of roads is not widely available because it is not in the peer-reviewed literature. For example, studies documenting the effects of roads on stream sedimentation have been reported in documents of state departments of transportation, the U.S. Army Corps of Engineers, and the World Bank. Although much of this literature is available through bibliographic databases, it is not included in scientific abstracting services and may not be accessible to a broader research community. Also, the data needed to evaluate regulatory programs are not easily accessible or amenable to synthesis. The data are typically contained in project-specific environmental impact statements, environmental assessments, records of decision, or permits (for example, wetlands permits), which are not easily available to the scientific community.
Recommendation: Studies on ecological effects of roads should be made more accessible through scientific abstracting services or through publication in peer-reviewed venues. The Federal Highway Administration, in partnership with state and federal resource-management agencies, should develop environmental information and decision-support systems to make ecological information available in searchable databases.
CONCLUSION: Transportation agencies have been attempting to fill an institutional gap in ecological protection created by the multiple social and environmental issues that must be addressed at all phases of road development. The gaps often occur when problems arise that are not covered by agency mandates or when agencies need to interact with other organizations in new ways. Even when transportation agencies
work toward environmental stewardship, they cannot always do the job alone.
Recommendation: Transportation agencies should continue to expand beyond their historical roles as planners and engineers, increasing their roles as environmental coordinators and stewards. Transportation planners and natural-resource planners should collaborate to promote integrated planning at comparable scope and scale so that the efforts can support mutual objectives. This collaboration should include federal, state, and county resource-management agencies; nongovernmental organizations; and organizations and firms involved in road construction. Incentives, such as funding and technical support, should be provided to help planning agencies, resource agencies, nongovernmental groups, and the public to understand ecological structure and functioning across jurisdictions and to interact cooperatively.