The benefits and costs of roads for water

as the protective approach and will also reduce maintenance—and sometimes even construction—costs (see the section titled “The Benefits and Costs of Roads for Water”).

The resilience plus approach is a preferable option compared with the protective or basic approach to climate resilience. By building roads that can serve several purposes beyond transport, and by making these functions part of the design and development of roads, roads can be created that (a) reduce the often substantial collateral damage caused by uncontrolled road water on the landscape around them; (b) are likely to have lower maintenance costs, will often suffer less downtime, and are generally better able to withstand weather effects, including those caused by climate change; and (c) generate substantial benefits through water management, including by harvesting water for beneficial uses. In other words, rather than being a source of landscape degradation, roads can become instruments for climate change resilience.

There are two levels to this resilience plus approach. The first level is adaptive resilience. Adaptive resilience makes use of the road infrastructure as it is but adds measures to improve water management. The second level is proactive resilience. Proactive resilience goes back to the drawing board and reconsiders all aspects of the road, including the road alignment. The proactive approach calls for designing roads that optimally contribute, within economic parameters, to better land and water management, in addition to allowing for better communication and coordination among stakeholders involved in road design.

These different approaches—protective resilience, adaptive, and proactive— are sometimes complementary. While the first goal of roads for water is to avoid developing roads that introduce new problems (notably through the proactive approach), measures aimed at protective or basic road resilience can be incorporated in and complemented by approaches at the adaptive and proactive levels. Table 1.1 describes the measures applied under these three increasing levels of road resilience for different geographies. Table 1.2 describes how the three levels affect different elements of roads.

THE BENEFITS AND COSTS OF ROADS FOR WATER

With global investment in roads of Us$1 trillion to Us$2 trillion per year, of which 40 percent is in developing countries, widespread adoption of Green Roads approaches can leverage investment at a transformative scale, making road development and maintenance a vital tool for achieving climate resilience, water security, and productive use of natural resources. dulac (2013) estimates that 25 million kilometers of paved road-lanes and 335,000 kilometers of railtrack will be added from 2010 to 2050, a 60 percent increase. The estimated cost of this new infrastructure in roads and railroads over four decades is Us$45 trillion. Unpaved road networks, which make up the majority of roads in most countries, will also continue to expand, adding to this total. future growth and upgrading of road networks present considerable opportunities to build in infrastructure productivity from the very beginning.

The economic case for roads for water is based on three key observations from implementation in the field:

• The Green Roads approach provides triple benefits: reduced road maintenance costs, reduced landscape degradation, and improved access to water for productive and consumption uses. Roads for water can not only preserve