Final answer:
Jackson argues that roads, as a powerful element in the accessible landscape, need to be handled carefully to prevent them from undermining and destroying the existing order in a community or society.
Step-by-step explanation:
Jackson means that the road, as part of the accessible landscape, has the power to greatly influence and potentially disrupt the existing order. He suggests that if not properly managed and monitored, the road can undermine the established structures and systems in a community or society. For example, the construction of a new highway may lead to the destruction of natural habitats and the displacement of local communities, which can have a significant impact on the existing social, economic, and environmental order.