The Transamazonica Highway in Brazil is going to be both, useful and destructive, depending on the point of view.
The biggest advantage of this highway is that it will connect the cities, towns, and villages in the Amazon rain forest with the rest of Brazil, as they now are very isolated and it very hard to travel to any place in the country from there.
The biggest disadvantage is that the highway will be cutting right through the rain forest, and for sure, millions of animals will die on the highway by getting hit by the vehicles driving on it, as the rain forest animals are not aware of the dangers of the roads.