Highway projects have the potential to result in significant social, environmental, and economic effects and, as a consequence, are the subject of a broad range of environmental regulation. Potential impacts include effects on
• Community cohesion
• Land use
• Minority and disadvantaged populations
• Surface and groundwaters
• Wetlands
• Coastal zone resources
• Navigable waters
• Wild, scenic, and recreational rivers
• Flood plains
• Water quality
• Important ecological resources, including wetlands and threatened and endangered species
• Significant historic and archaeological resources
• Important visual resources
• Public parklands
• Utilities
• Prime agricultural lands
• Air quality
• Noise
• Energy
• Exposure to contaminated and hazardous materials
• Public health
Recent court rulings also suggest the need to consider potential effects on global climate change and related ecological impacts.
The impacts of highway projects may be both temporary (short-term effects that occur during construction of a facility) and permanent (long-term effects resulting from the operation of a facility). Both short — and long-term impacts can be direct, indirect, or cumulative.
• Direct impacts are effects directly caused by an action that occur at the same time and place and result from the direct use of land or resources.
• Indirect impacts are effects indirectly caused by an action and are later in time or farther removed in distance from the location of a facility, but which are still reasonably foreseeable, including growth inducing effects and other effects related to induced changes in the pattern of land use, population density, or growth rate.
• Cumulative impacts are impacts which result from the incremental impact of an action when added to other past, present, and reasonably foreseeable future actions regardless
of what agency or person undertakes such other actions. Cumulative impacts can result from individually minor but collectively significant actions taking place over a period of time.
All of these effects must be considered in evaluating the environmental impacts of highway projects.
