Abstract
The unprecedented and irreversible loss of biodiversity in modern times is caused primarily by the elimination or degradation of natural habitats. Because the construction and improvement of roads sometimes lead, directly or indirectly, to the loss and degradation of natural habitats, road construction and biodiversity aims are often at odds. However, many potentially serious conflicts between road projects and biodiversity conservation can be avoided. Induced negative impacts can be minimized by careful project siting. Where some natural habitat loss is inevitable, appropriate mitigation may include establishment of strict protection zones alongside the road or compensatory protected areas elsewhere. Such mitigation requires effective collaboration, for example, between the agencies responsible for roads and protected areas. Direct adverse impacts of road works on biodiversity also can be significant but are generally simpler to avoid or mitigate because they are more fully under the control of road construction agencies, contractors, and concessionaires. Biodiversity loss and environmental damage can be considerably reduced when planners and road construction agencies site roads adjacent to existing railways, pipelines, or transmission lines; practice sound road engineering; maintain good drainage and natural water flows; minimize roadside habitat loss; and exercise care in the siting and design of borrow pits, construction camps, and other complementary facilities. Environmental rules for contractors, including transparent penalties for noncompliance, need to be incorporated in bidding documents and contracts. Ideally, road projects are designed and implemented so as to avoid or compensate adequately for any adverse impacts on natural habitats and biodiversity. Through mitigation measures, potentially controversial projects can even produce significant net environmental benefits—a win-win outcome.
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