Transport infrastructure represents a significant sunken public and private investment that is fundamental to the functioning of society. These assets are often long-lived and, if regularly maintained, are designed to deliver specified and predictable services over their entire lifetime. Hazards that may degrade asset performance or interrupt network services are generally well-known and are accounted for in transport infrastructure, network planning and design. Thus, even though the natural variability of extreme weather events have sometimes caused significant disruption, these risks were knowable and their impacts have historically been mitigated. With climate change, this is no longer true. This report reviews the range of threats to transport system performance that are posed by climate change and provides guidance to transportation asset owners and network managers to help ensure asset integrity and contribute to continued network performance.

Broad evidence indicates that man-made emissions of greenhouse gases are changing the climate, and many of the potential impacts of climate change on meteorological conditions can affect the performance of transport systems and the viability of transport infrastructure. Summer temperatures will increase and heat extremes will become more frequent and last longer. Winter temperatures will become milder but temperature amplitudes may increase and swings between sub-zero and above freezing point temperatures will occur more often. Warming of the Arctic regions will lead to deeper permafrost melting (and soil heaving) with loss of summer sea and land ice. Winters will see more precipitation in the Northern Hemisphere, and more of it will be rain.

Much of the understanding of the linkages between human-caused emissions of greenhouse gases and other anthropogenic climate changes is based on complex climate models that have generally performed well in tracking current global temperatures. Nonetheless, these models are approximations (albeit very sophisticated ones) that cumulate several possible sources of errors. This chapter will discuss in general terms the current scientific state of understanding of the direction and scope of climate change and how these changes may give rise to transport infrastructure or network service-damaging hazards. It also addresses the extent with which confidence can or should be ascribed to projections of future hazards such as temperature change, sea level rise, changes in precipitation, etc.

Individual assets and groups of infrastructure elements are vulnerable to a number of climate and weather-related phenomena. This chapter will review the composition and life cycle of different transport infrastructure asset classes and will describe their exposure and vulnerability to disruption, damage and failure in light of climate-related factors. It will also provide an indicative overview of some of the potential costs faced by the transport sector as climate regimes evolve.

Prioritising dependable, robust and resilient network connectivity as the reference performance criteria for infrastructure adaptation policies ensures that these policies consistently enable and preserve the core benefits delivered by infrastructure assets. This chapter outlines how transport infrastructure owners and network managers can embed network access and connectivity performance into their asset management policies. This chapter also describes climate change adaptation frameworks for transport authorities and asset owners. It discusses, in essence, the question of “How to prepare to adapt?” Having a coherent framework for adaptation policies can go far to ensure that risks are highlighted, responsibilities allocated, interventions are prioritised and that strategic decisions are not overlooked.

Managing uncertainty is not a new aspect of transport policy – considerable climate change uncertainty surrounds future demand projections and the global trends that can impact flows of people and goods. There is also micro-level uncertainty on how specific parts of the transport networks may be affected by disruptions. Addressing these incidents and sources of uncertainty lies at the heart of transport decision making. This chapter looks at strategies including, but not limited to, cost-benefit analysis to address this “deep” uncertainty for transport infrastructure and services whose life-times extend well into the future.