1. Environmental impact assessment

Federal Law No. 12,379/2011 establishes Brazil’s National Transport System (SNV) and defines among its objectives ensuring national unity and regional integration; guaranteeing the strategic transport network required for national security; promoting physical integration with the transport systems of neighboring countries; efficiently accommodating major freight flows through strategic export and supply corridors; and providing facilities for interstate and international passenger and freight transport. Article 11 further establishes that implementation of an SNV component must be preceded by preparation of the corresponding engineering design and by acquisition of the required environmental licenses. The Ministries of Transport and Defense prepare the National Logistics and Transport Plan (PNLT), which supports the strategic definition of sector policies.

Thus, when the environmental licensing process for a road connection begins, higher levels of government and representative institutions have already determined that the connection—and the transport mode itself—is necessary. The environmental authority must then assess its environmental feasibility, considering both siting and technological alternatives. Siting alternatives comprise possible alignments between points A and B, potentially passing through points X and Y when these are defined as project destinations. Technological alternatives may include, for example, pavement type and engineering structures such as tunnels, viaducts, bridges and elevated sections.

To determine environmental feasibility, the environmental authority must have sufficient information to assess whether implementation under specified conditions would cause damage of a magnitude capable of compromising the preservation of ecological processes, as required by Article 225 of the Federal Constitution. A single road is unlikely to compromise an ecological process at the national scale in a continental country such as Brazil. However, the cumulative and synergistic effects of projects forming the road network must also be considered, together with the regional-development pressures and land occupation stimulated by that network. Baseline characterization of the physical, biotic and socioeconomic environments supports prediction of impacts arising from project implementation in the process known as Environmental Impact Assessment (EIA).

If technological and siting alternatives can be identified that allow the project to be implemented without impacts that compromise ecological processes at the scale under consideration, the project may be regarded as environmentally feasible. The magnitude of environmental damage that cannot be mitigated, but does not prevent project feasibility, is assessed according to the methodology established by Federal Decree No. 6,848/2009 for calculation of the environmental compensation provided for in Article 36 of Federal Law No. 9,985/2000 (the National System of Protected Areas Law). Siting alternatives intended to minimize or prevent damage are likewise defined from the baseline assessment, considering the biological, physical, social and economic factors involved.

The present analysis focuses on assessing the magnitude of impacts on wildlife and the technical alternatives available to mitigate them, on the assumption that adoption of suitable measures will be sufficient to ensure project feasibility with respect to this component. Among the various definitions of environmental impact, that adopted by Wathern (1988 apud Sánchez 2008) is particularly appropriate because it incorporates the dynamic nature of environmental processes. It does not merely compare conditions before and after project implementation, but also considers the expected trajectory of environmental quality in the affected area: a change in an environmental parameter, over a given period and within a given area, resulting from an activity compared with the condition that would have occurred had that activity not begun.

For roads and wildlife this concept is especially important. Even where a currently significant negative impact is identified, the high cost of many mitigation measures and limited available resources mean that priority areas should also be selected according to their likelihood of remaining ecologically important in the future. For example, restoring connectivity between two habitat fragments that are highly likely to disappear soon through conversion to agriculture or urbanization may have a questionable cost–benefit ratio compared with maintaining connectivity between fragments with good prospects for long-term conservation, even if current road-mortality indicators are less pronounced in the latter. Area importance, the likelihood of future persistence and the expected magnitude of impact should therefore be central elements in defining mitigation priorities.

Conceptually, it is also important to recognize that the road itself is not an environmental impact. It is a cause; the impacts are the consequences of the human action represented by its construction and operation (Sánchez 2008). Similarly, the concepts of “environmental aspect”, introduced by the ISO 14000 series and incorporated into NBR ISO 14001:2004, and “environmental effect”, as proposed by Munn (1975 apud Sánchez 2008), are distinct from environmental impact. An environmental aspect or effect can be defined as a change in a natural or social process resulting from human action. Thus, a road project produces the environmental effect of traffic, which in turn can produce the environmental impact of wildlife mortality. In this logic, environmental effects form the interface between causes (human actions) and consequences (environmental impacts).

Environmental Impact Assessment is part of decision-making and should therefore be carried out before project implementation. In some situations, however, it may be desirable to quantify the impacts of an activity that is already operating, such as an existing road. In that case, the recommended term is Environmental Damage Assessment: rather than predicting future impacts, it evaluates the current situation in relation to the condition assumed to have existed in the past. In both cases, characterization of present environmental conditions is termed the environmental baseline assessment (Sánchez 2008) and forms part of the environmental studies required for licensing. A proposal for the minimum information needed for an effective baseline assessment to support decision-making is presented in Section 1.4 of this guide.

When preparing environmental studies, technical teams should be able to predict the impacts of the road project within the environmental scenario, propose alignment changes that avoid those impacts, and recommend mitigation measures that reduce their magnitude.

Translation note: This English version was preliminarily translated using ChatGPT and has not yet undergone human review.