Community impacts assessment is not only a critical part of the NEPA process, it is essential for building trust and securing grassroots support for projects. Direct impacts to communities, particularly neighborhoods, are real time and reasonably well understood, and there are proven techniques and methods to identify and quantify them. Environmental justice impacts, especially those of a cumulative nature, are more problematic, given the dynamics of community growth and development and the broad array of contributing factors.

One facet of environmental justice impacts that may be overlooked during the environmental assessment of current projects is the past effect of government-sponsored construction on the same communities in which these current projects are now proposed. Many neighborhoods may have been previously adversely impacted by substantial numbers of business and residential acquisitions, the introduction of physical barriers that eliminated or impeded access, the intrusion of undesirable physical elements, such as traffic noise and air pollutants and a general erosion of community cohesion. As aging transportation facilities are slated for reconstruction and improvements, these communities will be affected once more. Too frequently, minority and low-income neighborhoods bear the brunt of these cumulative imapcts, raising environmental justice concerns.