June 2008

Climate Change Holds Serious Implications for Transportation Infrastructure 

Leo von Scheben, P.E., commissioner of the Alaska Department of Transportation & Public Facilities, has seen a lot of change in his state's weather patterns over the last 10 years. Rain in January and a man waterskiing on Christmas are both "unheard of" recent phenomena that von Scheben attributes to climate change. He describes how warmer temperatures and freeze-thaw cycles are "causing havoc" in his state, putting stress on pavement and degrading highways, increasing runoff and overflowing rivers, and melting pack ice leading to erosion of shorelines.

Experiences like von Scheben's are beginning to generate urgent discussions among transportation engineers and planners. Several recent reports stress that the effects of climate change on transportation infrastructure will be serious and need to be addressed now. The Transportation Research Board of the National Academies, the U.S. Climate Change Science Program, and the U.S. Department of Transportation's Center for Climate Change and Environmental Forecasting have all released reports examining the effects of climate change on transportation infrastructure.

"We can no longer ignore the evidence that suggests that climate change is going to influence and impact on transportation," says Henry "Gerry" Schwartz, P.E., chair of the TRB committee that produced the report Potential Impacts of Climate Change on U.S. Transportation. "And we'd be derelict in our duty if we didn't respond to that professionally in planning, design, and operating procedures."

Schwartz, an NSPE member and retired chairman of Svedrup/Jacobs Civil Inc., says transportation professionals have traditionally believed that climate change is a long-term process that can be adapted to gradually. However, five effects identified in the TRB report "suggest that the impacts are going to be more serious and more of a surprise than transportation professionals realize."

Those effects are increases in very hot days and heat waves, increases in Arctic temperatures, rises in sea levels, increases in intense precipitation events, and increases in hurricane intensity.

Flooding of coastal roads, railways, transit systems, and runways is potentially the greatest impact of climate change on U.S. transportation infrastructure, note the authors of Potential Impacts. That's due to global rising sea levels, storm surges, and, in some areas, land subsidence.

The state of Alaska is now relocating several communities due to shoreline erosion, von Scheben reports. In addition, he expects to see movement of and structural damage to buildings built on permafrost.

The TRB report offers 14 recommendations for dealing with the effects of climate change on transportation infrastructure, starting with inventorying critical infrastructure in light of climate change projections. That's the step the Washington State Department of Transportation is now beginning to work on, says Deputy State Design Engineer Nancy Boyd, P.E.

"As an agency, now we're just educating ourselves," she says. The department is "very interested in monitoring what the latest scientific studies are predicting for the Puget Sound area in particular, what it means for our infrastructure, and what we need to consider for projects."

Alaska DOT&PF is also at the data-gathering stage. For example, the organization is working with representatives from Canada's Yukon Territory to collect data and discuss possible solutions such as extending the side slopes of roads and putting more fill over permafrost areas to insulate them.

While all of the 14 recommendations in the TRB report are important, Schwartz stresses the need for public and private infrastructure owners to incorporate climate change analysis in capital and renewal planning. He also emphasizes that transportation planners and designers should use probabilistic, not deterministic, analyses and design approaches. That means basing decisions on the current probability of an event rather than on historical averages. What was once considered a 100-year storm, for example, may now be a 50-year or even 20-year storm.

"There are some very good techniques in uncertainty planning [that] by and large haven't been used by transportation people," Schwartz says.

He also points to the need for more communication between transportation professionals and climate scientists, two groups that historically have not had much contact, he says. Transportation professionals need better data that explains what's happening in a region or locality, he says, and climate scientists need to know the exact questions that need answering.

Boyd agrees. "[Data] will help us develop better predictive models, and those models will help us make better design decisions," she says.

It's the same risk-based decision making that engineers are used to doing, she explains, but the science is evolving so quickly that planners really need to stay on top of it to make decisions based on the best available information.

Schwartz points out that the cost of adapting is incremental in relation to the price of constructing or reconstructing major infrastructure. Raising the elevation five feet when building a bridge, he says, is much less expensive than going back in and replacing it later.

Says von Scheben: "I think climate change is something we have to design to now. I think it's here to stay for a while, and it's real." Boyd concurs, saying the discussion about the issue needs to move from what's causing it to how to adapt.

Although we may not be 100% sure about the problem, Schwartz says, we can't afford to wait until we're sure. "Do we wait 50 years and find out those guys 50 years ago were dead right?" he asks. "It's better to do something over 50 years and perhaps find they weren't quite right; it's not as bad as they thought."

Canadian Engineers Indicate High Awareness, Low Action on Climate Change
Professional engineers in Canada realize the effect of climate change on their work, but few consider the issue in their current decision making, according to a survey by the Canadian Standards Association (CSA).

Although 82% of survey respondents said they accept that climate change issues will affect their practice, 27% said they always or mostly consider the effect of climate change in their decisions today and 28% said they never consider climate change.

Of the various tools for addressing climate change, energy efficiency and low-emissions solutions were most familiar among respondents. While 77% were somewhat familiar or very familiar with these tools, fewer were somewhat or very familiar with other techniques, such as

• Designing infrastructure that can be modified as the effects of climate change occur (33%);
• Identifying locations vulnerable to climate change and modifying designs accordingly (35%); and
• Considering different climate change scenarios for design, maintenance, and planning (36%). 

Almost three out of four engineers indicated that they need more information on climate change, with 54% saying they will likely seek more information in the near future.

"There may be a gap between what is being emphasized today in engineering schools and what needs to be emphasized when it comes to preparing Canada's future engineers for some of the challenges that they will face," says the CSA report.

Potential Climate Changes and The Effects on Transportation

Potential Climate Change	Example(s) of Operations Impacts	Example(s) of Infrastructure Impacts
Increases in very hot days and heat waves	Limits on construction activity  due to health and safety concerns.	Thermal expansion on bridge joints and paved surfaces. Concerns regarding pavement integrity, for example, softening.
Increases in Arctic temperatures	Longer ocean transport season and more ice-free ports in northern regions. Possible availability of a northern sea route.	Thawing of permafrost, causing subsidence of roads, rail beds, bridge supports, pipelines, and runway foundations.
Rising sea levels, combined with  storm surges	More frequent interruptions to coastal and low-lying roadway and rail travel due to storm surges. More severe surges requiring evacuation.	Inundation of roads, rail lines, and airport runways in coastal areas. Erosion of road base and bridge supports, reduced clearance under bridges.
Increases in intense precipitation events	Increases in weather-related delays and traffic disruptions. Increased flooding of evacuation routes.	Increases in road and tunnel flooding, road wash out, landslides and mudslides that damage roads, and scouring of pipeline roadbeds.
More frequent strong hurricanes (Category 4–5)	More frequent and potentially more extensive emergency evacuations. More debris on roads and rail lines, interrupting travel.	Greater probability of infrastructure failures. Increased threat to stability of bridge decks. Impacts on harbor infrastructure.
More frequent strong hurricanes (Category 4–5)	More frequent and potentially more extensive emergency evacuations. More debris on roads and rail lines, interrupting travel.	Greater probability of infrastructure failures. Increased threat to stability of bridge decks. Impacts on harbor infrastructure.

Adapted from Potential Impacts of Climate Change on U.S. Transportation, the National Research Council of the National Academies