Sustainable roads

Image Credit: Marcello Guerreiro

Written by Marcello Guerreiro

August 8, 2023

Vehicle collisions with animals represent the main and most harmful impact of roads on biodiversity, since it is a process that leads to a direct reduction of natural populations and intensifies the barrier effect (Fahrig & Rytwinski 2009). The intensity of the barrier effect in a species depends on the behavioral reactions to the presence of the road in the landscape (Jaeger et al. 2005). A species that is repelled by the road has a low risk of mortality from being run over, but its population groups are increasingly geographically isolated. In this sense, the road fragments populations that remain isolated in habitat patches on opposite margins and subject to the deleterious effects of population size reduction and local extinction (Hanski & Ovaskainen 2002; Jaeger et al. 2005). Measures that ensure connectivity between subpopulations allow the exchange of individuals and increase their population viability (Hanski & Ovaskainen 2003). Therefore, the regional persistence of the species affected by the path depends on the success of some individuals in crossing the barrier through successful crossings, even occasionally.
The objective of this project is to evaluate the effectiveness of the environmental mitigation measures implemented on the BR-101/RJ Norte highway, under the concession of Arteris Fluminense, the project executing company.
The mitigation measures are directed at the risk of vehicle collisions with the native fauna of the region that the road crosses, as well as at reducing the geographic isolation between the population groups that exist in the areas on both sides of the road. Among the measures are the protection fences to direct the animals to the entrances of the lower corridors (underground and adapted bridges), which are part of the set of 37 fauna corridors installed. Among them, 10 uneven steps cup by cup with pioneering structures and designs in Brazil, 15 underground passages of different sizes, 11 adapted bridge sections, as well as the first vegetated viaduct on a federal highway in the country. This complex of structures for fauna covers approximately 70 kilometers of the BR-101/RJ North, in a section located between the municipalities of Rio das Ostras and Rio Bonito (Km 190 to Km 261). If the measures are effective, the effect will be a barrier caused by the sidewalk, thus reducing the rate of pedestrians being run over, and/or increasing the number of wildlife crossings from one side of the sidewalk to the other. , allowing the establishment of new individuals in each bank.
For the identification and quantification of the species that benefit from the passages, trap cameras were used, capable of shooting themselves to detect movement, the equipment was programmed to record images through videos, with a duration of 20 seconds, 24 hours a day. of the day, without interruption. With this, it was possible to diagnose all the fauna that benefits from the passages. During the crossings, 267 animals were registered using the passes through the systematic monitoring of the passes of the lower and upper fauna up to now. The overpasses were the ones with the highest number of crossings, with 254 records of five different species (Figure 6). In the lower passages, despite having a lower number of crosses, with 13 records, a greater diversity of species (7) was covered in relation to the upper passages. Of the 13 animal species registered, two are threatened with extinction both at the state, national and global level, being the golden lion tit (Leontopithecus rosalia) and the collared sloth (Bradypus torcuato).
The animal with the highest number of crossings on the high passes was the marmoset ( Callithrix sp.) with 172 actual crossings (individually), representing about 68% of all recorded crossings. The golden lion tamarin was the second animal with the highest number of matings (73), followed by the long-eared opossum (Didelphis aurita) (6), the hedgehog (Coendou spinosus) (1), collared sloths, and marsupials of the Order Didelphimorphia.

In the lower faunal steps, the species with the highest number of crossings in the lower faunal steps was the otter (Lontra longicaudis) with four crossings, followed by the ferret (Galictis cuyo), raccoon (Procyon cancrivorus) and lesser armadillo (Dasypus septemcinctus). , both with two crosses. The coati (Nasua nasua), the capybara (Hydrochoerus hydrochaeris) and the tegu lizard (Salvator merianae) were only recorded once crossing the underground stairs.

The project has a pioneering character, since it represents the first federal road in the country to have a fauna path the size of a viaduct with vegetation connecting the landscape from one shore to the other, in addition to having a well-known and incomparable average for Brazilians. standards of 1 wildlife crossing every 1.9 kilometers of road in this stretch of approximately 70 kilometers located between Rio das Ostras and Rio Bonito, passing through the Environmental Protection Area (APA) of the São João – Mico-Leão-Dourado River Basin, and on the borders of the União and Poço das Biological Reserves Antas, in the center-north of Rio de Janeiro. The name of this APA, by itself, further denotes the relevance of this project, since it is the region of occurrence of species at an alarming level of threat of extinction in the State of Rio de Janeiro and in Brazil in general, such such as the golden lion tamarin ( Leontopithecus rosalia ) and the collared sloth ( Bradypus torquatus ), which are being directly benefited by the mitigation measures implemented, since the use of some of the upper fauna passages from crown to canopy by part of them.
In addition, it can be considered innovative due to its methodological plan and sampling design, which will allow various analyzes to be carried out to infer and compare the degrees of effectiveness between the different types of measures to mitigate the impacts caused to fauna on the highway. The project is currently in execution, but it is already a reference, serving as a reference for other highway concessionaires in Brazil, who seek information on this process, with the aim of improving their respective environmental management and decision-making on the strategy of mitigation. of impacts on fauna, with the BR-101/Norte RJ, managed by Arteris Fluminense, something very close to what is seen as an ecologically friendly and sustainable highway.

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