"All modes of transport are sensitive to weather and climate to some extent." ⁽¹⁷⁾

Roads, railways, airport runways, shipping terminals, canals and bridges are examples of the facilities and structures required to move people and freight. Climate and weather affect the planning, design, construction, maintenance and performance of these facilities throughout their service life. Although our current system is quite robust, future weather conditions may reach or exceed the limits of tolerance for some parts of the system. In other cases, a warmer climate may translate into savings for those who build, maintain and use Canada's transportation infrastructure.

Surface Transportation Issues Related to Changes in Temperature

There is strong evidence that both minimum and maximum temperatures have been warming in most of Canada over the past 50 years,⁽²¹⁾ and that changes in temperature distribution are expected to continue throughout the present century. The associated impacts of these changes on transportation infrastructure will vary regionally, reflecting differences both in the magnitude of climate changes, and in environmental conditions. For example, infrastructure in northern regions of Canada (discussed separately below) is particularly sensitive to warming temperatures. In general, there is expected to be an increase in the frequency of extreme hot days in most regions of Canada, and a decrease in the frequency of extreme cold days.⁽¹⁵⁾ Overall, the effects of changes in temperature will likely be more pronounced in winter, when future warming is projected to be greater than during the summer months.

An increase in the frequency and severity of hot days raises concerns that Canada's roads could experience more problems related to pavement softening and traffic-related rutting, as well as the migration of liquid asphalt (flushing and bleeding) to pavement surfaces from older or poorly constructed pavements. Asphalt rutting may become a greater problem during extended periods of summer heat on roads with heavy truck traffic, whereas some flushing could occur with older pavements and/or those with excess asphalt content. These problems should be avoidable with proper design and construction, but at a cost.⁽²²⁾

Cold temperatures in winter are currently a much greater concern for transportation in Canada than summer heat. Cracking of pavements related to low-temperature frost action and freeze-thaw cycles is a well-recognized problem in most of southern Canada. The 1992 Royal Commission on National Passenger Transportation concluded that environmental factors account for the greatest portion of pavement deterioration, up to 50% of deterioration on high-volume roads and as much as 80% on low-volume roads.⁽²³⁾ Premature deterioration of road and runway pavements is related to high frequencies of freeze-thaw cycles, primarily where subgrades are composed of fine-grained, saturated material.⁽²⁴⁾ Southern parts of Canada may experience fewer freeze-thaw cycles as a result of climate change,⁽²⁵⁾ and thus experience less frost damage to pavements. By contrast, in northern areas, pavement structures stay strong throughout the winter at present because the subgrade remains frozen until spring.⁽²²⁾ Milder winters, with more freeze-thaw cycles, would accelerate road deterioration and increase maintenance costs in northern areas. On the other hand, an increase in winter thaws in these areas could be at least partially offset by fewer springtime thaws. At present, there is a solid understanding of the physical processes at work, but a detailed inventory and assessment of the vulnerability of Canada's road system to changes in freeze-thaw cycles is required to estimate the net effects and to begin developing adaptive strategies for new or reconstructed roads.

Rail infrastructure is also susceptible to temperature extremes. Railway track may buckle under extreme heat, and this has been suggested as a possible contributing factor in the July 29, 2002 Amtrak rail incident in Maryland.⁽²⁶⁾ As with roads, extreme cold conditions are currently more problematic for railways than severe heat, and result in greater frequencies of broken railway lines and frozen switches, and higher rates of wheel replacement. On balance, it is expected that warming will provide a modest benefit for Canadian rail infrastructure, except in regions underlain by permafrost (as discussed in the next section). It should be emphasized, however, that there has been very little research on climate change impacts on rail infrastructure in Canada.

Issues Related to Temperature Change in Northern Regions

Climate warming raises a number of issues for transportation infrastructure that are unique to northern Canada, where the most significant warming is expected and where the physical landscape is highly sensitive to temperature changes. Permafrost (ground that remains below 0°C for more than 12 consecutive months) underlies almost half of Canada⁽²⁷⁾ and provides important structural stability for much of our northern transportation infrastructure. This includes all-season roads, airstrips and some short-line rail operations, such as the OmniTRAX line to the Port of Churchill in Manitoba. Degradation of permafrost as a result of climate warming will result in increased depth of the seasonal thaw layer, melting of any ice that occurs in that seasonal thaw zone, and warming of the frozen zone, which reduces its bearing capacity. Paved runways are likely to be among the structures most vulnerable to permafrost changes, as they readily absorb solar energy, further contributing to surface warming.

Ice roads, which are constructed by clearing a route across frozen ground, lakes or rivers, play an important role in northern transportation, both for community supply and for resource industries (Figure 2). Although the operating window varies from location to location and year to year, these roads are typically used from November-December to March-April. Milder winters, as projected under climate change, would shorten the ice-road season by several weeks⁽²⁸⁾ unless additional resources were available to apply more intensive and advanced construction and maintenance techniques. In 1998, higher than normal temperatures led to the closure of the winter road to Fort Chipewyan, and the Alberta government had to help residents of the town obtain critical supplies.⁽²⁹⁾ A shorter ice-road season may be partially offset by a longer open-water or ice-free season in areas accessible by barge. However, given the current limitations of monthly and seasonal climate forecasts, planning for barge versus winter-road transport is likely to be imperfect. Furthermore, the port infrastructure and services in some regions may be inadequate to handle increased use, and many areas that currently rely on ice roads, such as the diamond-mining region of the Northwest Territories, are landlocked and cannot take advantage of barge transport.

Figure 2: Ice road in Yellowknife. Photo courtesy of Diavik Diamond Mines Inc.

Thus, warmer temperatures associated with climate change could create new challenges for economic development in some northern regions.

Infrastructure Issues Associated with Changes in Precipitation

The impacts of climate change on future precipitation patterns are much less certain than those on temperature, due in part to the highly variable nature of precipitation and limited ability of current climate models to resolve certain atmospheric processes. It is thought, however, that annual precipitation is likely to increase over much of Canada, with an increase in the proportion of precipitation falling as rain rather than snow in southern regions. In the past, there have been many examples of damage to transportation infrastructure due to rainfall-induced landslides and floods. For example, a 1999 debris flow in the Rocky Mountains, thought to have been caused by a localized rainfall event, blocked traffic on the Trans-Canada Highway for several days during the tourist season.⁽³⁰⁾ In 1997, a mudslide in the Fraser Canyon washed out a section of Canadian National railroad track, derailing a freight train and killing two crewmen (reference 31, see Figure 3).

Figure 3: Derailed Canadian National train caused by landslide in the Fraser Canyon. Photo courtesy of S. Evans.

If the timing, frequency, form and/or intensity of precipitation change in the future, then related natural processes, including debris flows, avalanches and floods, would be affected. For example, there are concerns that future changes in hydroclimatic events, particularly extreme rainfall and snowmelt, could result in more frequent disruptions of the transportation corridors in the mountains of western Canada as a result of increased landslide frequency.⁽³²⁾ Similar concerns exist about the stability of areas underlain by clay-rich sediment in parts of eastern Ontario and southern Quebec.⁽³³⁾ In addition to affecting roads and railroads, other critical infrastructure (e.g., pipelines) is also vulnerable to precipitation-triggered slope instability (see Box 1).

Future increases in the intensity and frequency of heavy rainfall events⁽³⁵⁾ would have implications for the design of roads, highways, bridges and culverts with respect to stormwater management, especially in urban areas where roads make up a large proportion of the land surface.⁽³⁶⁾ Precipitation and moisture also affect the weathering of transportation infrastructure, such as bridges and parking garages. Accelerated deterioration of these structures may occur where precipitation events and freeze-thaw cycles become more frequent, particularly in areas that experience acid rain.^{(37, 38)}

BOX 1: Effect of slope instability on linear infrastructure⁽³⁴⁾

Changes in the duration, amount and intensity of precipitation have the potential to increase ground movement and slope instability. This soil movement could, in turn, threaten the structural integrity of linear infrastructure, including pipelines, roads and railroads, by placing additional strain on these structures. In this study, researchers examined the integrity of pipelines in western Canada by using a modelling approach to predict the effect of changes in precipitation on slope movement rates. Results allowed the identification of critical thresholds that will help industry and government regulators plan for potential impacts of climate change. Repaired pipeline. Photo courtesy of I. Konuk.

Maintenance Costs Associated with Snow and Ice

Governments and industries spend large sums of money responding to Canada's harsh winter climate. As such, there is general optimism that a warmer climate would reduce costs related to snow and ice control on surface transportation routes, and de-icing of planes.

In Canada, provincial and local governments together spend about $1.3 billion annually on activities related to snow and ice control on public roadways. These include the application of abrasives (sand) and approximately 5 million tonnes of road salt, snowploughing and snow-bank grading, and the construction of snow fences.^{(39, 40)} Empirical relationships between weather variables and winter maintenance activities indicate that less snowfall is associated with reduced winter maintenance requirements.^{(41, 42)} Thus, if populated areas were to receive less snowfall and/or experience fewer days with snow, this could result in substantial savings for road authorities. There could also be indirect benefits, such as less salt corrosion of vehicles and reduced salt loadings in waterways, due to reduced salt use. However, studies to date on this topic do not represent all climatic regions of Canada. Nor do they account for possible changes in storm characteristics, such as icing.⁽⁴³⁾

It is well recognized that individual storms can account for a large percentage of total seasonal costs.⁽⁴³⁾ A succession of storms, in which the impacts are cumulative, can also result in substantial costs. For example, a series of winter storms, associated heavy snowfalls and extremely cold temperatures affected southern Ontario during the month of January, 1999.⁽⁴³⁾ In terms of the number of people affected, impaired mobility was the most significant impact. Repeated snowfalls exceeded the capacity of existing systems to maintain reliable air, road, rail and subway transportation services. Estimated economic losses, based on information from several government agencies and businesses, were more than $85 million. Organizations that coped well during the event cited the benefits of previous experience dealing with emergency situations and the ability to implement contingencies that reduced their reliance on transportation. Transportation authorities have generally responded to the event by redesigning their systems to withstand a higher threshold of winter hazard.

Rail companies also have winter operating plans and procedures for dealing with winter weather that cost millions of dollars each year. These include such measures as snow removal, sanding and salting, track and wheel inspections, temporary slow orders and personnel training. While milder or shorter winters are expected to benefit rail operations, this conclusion is based on limited research.

For air transport, "up to 50 million litres of chemicals are sprayed onto aircraft and runways around the world each year to prevent the build-up of ice on wings and to keep the runways ice-free." ⁽⁴⁴⁾ The main chemicals used in Canada are glycols for plane de-icing and urea for keeping airport facilities clear of snow and ice. Experts are optimistic that a warmer climate is likely to reduce the amount of chemicals used, thus reducing costs for the airline industry,⁽⁴⁴⁾ as well as environmental damage (e.g., water pollution) caused by the chemicals.

Finally, for marine traffic, icebreaking services constitute a major activity of the Canadian Coast Guard, and include organizing convoys and escorting ships through ice-covered waters, providing ice information and routing advice, freeing vessels trapped in ice and breaking out harbours.⁽²²⁾ If ice coverage and thickness are reduced in the future, vessels working in the same regions may require less ice-breaking capacity, which could save millions of dollars in capital and operation expenditures.⁽⁴⁵⁾ However, additional services of the Canadian Coast Guard may be required in the Canadian Arctic due to the potential for increased marine transport through the Arctic archipelago (see Coastal Zone chapter). Over the past three to four decades, decreases in sea-ice extent in the Arctic (see Fisheries chapter) have brought increased attention to the potential use of the Northwest Passage as an international shipping route.^{(46, 47)} In fact, many believe that continued warming will lead to substantial increases in shipping through Arctic waters (e.g., references 47, 48). However, although ice cover would decrease, conditions may become more dangerous because a reduction in seasonal ice would allow more icebergs from northern glaciers, and hazardous, thick, multiyear ice from the central Arctic Basin, to drift into the archipelago.⁽⁴⁹⁾ Overall, the potential opening of the Northwest Passage would present a range of new opportunities and challenges for northern Canada, including new economic development, sovereignty issues, and safety and environmental concerns.

Coastal Issues Related to Sea Level Rise

Average global sea level is expected to rise by between 9 and 88 centimetres by the year 2100, with considerable regional variation (reference 15; see also Coastal Zone chapter). Higher mean sea levels, coupled with high tides and storm surges, are almost certain to cause problems for transportation systems in some coastal areas of the Maritimes, Quebec, southwestern British Columbia and the Northwest Territories.⁽⁵⁰⁾ Various inventories of vulnerable sites and structures have been completed for Atlantic Canada (e.g., reference 8). With even a half metre (50 centimetres) rise in sea level, many causeways and bridges, some marine facilities (e.g., ports, harbours) and municipal infrastructure buried beneath roads would be at risk of being inundated or damaged. For some communities, flooding could render inaccessible key evacuation routes, emergency services and hospitals.⁽⁵¹⁾ The replacement value of the affected infrastructure has been estimated in the hundreds of millions of dollars, unless appropriate adaptations are made over the coming decades.

Some aviation infrastructure is also vulnerable to sea level rise. Of the nearly 1 400 certified or registered land-based airports and helipads in Canada, 50 are situated at five metres above sea level or less.⁽⁵²⁾ The largest of these is Vancouver International Airport, which is currently protected by dykes due to its low elevation on the Fraser Delta. Sea level rise could necessitate expanded protection or relocation of some of the affected facilities.