Planning for Systems Management 

& Operations as part of 

Climate Change Adaptation

March 2013
Foreword

This paper is a deliverable on a technical support task for the FHWA Office of Operations. The objective 

of the task is to develop white papers on emerging and current topics of interest to the Office. Topics for 

white papers were primarily identified and prioritized based on internal listening sessions with Office of 

Operations personnel. 

Notice

This document is disseminated under the sponsorship of the United States (U.S.) Department of 

Transportation in the interest of information exchange. The U.S. Government assumes no liability for 

the use of the information contained in this document. This report does not constitute a standard, 

specification, or regulation.

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' 

names appear in this report only because they are considered essential to the objective of the 

document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, 

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improvement.
Technical Report Documentation Page

1. Report No.

FHWA-HOP-13-030

2. Government Accession No. 3. Recipient's Catalog No.

4. Title and Subtitle

Planning for Systems Management & Operations as part of 

Climate Change Adaptation

5. Report Date

March 2013

6. Performing Organization Code

HOP

7. Author(s)

Deepak Gopalakrishna, Jeremy Schroeder, Amy Huff, Amy 

Thomas, Amy Leibrand

8. Performing Organization Report No.

Report

9. Performing Organization Name and Address

Battelle

505 King Ave.

Columbus, OH 43201

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

12. Sponsoring Agency Name and Address

Federal Highway Administration

Office of Operations (HOP)

1200 New Jersey Avenue, SE

Washington, DC 20590

13. Type of Report and Period Covered

Technical

14. Sponsoring Agency Code

FHWA

15. Supplementary Notes

Project performed in cooperation with the U.S. Department of Transportation, Federal 

Highway Administration. 

16. Abstract

This paper is a deliverable on a technical support task for the FHWA Office of Operations. 

The objective of the task is to develop white papers on emerging and current topics of interest 

to the Office. Topics for white papers were primarily identified and prioritized based on internal 

listening sessions with Office of Operations personnel. This white paper presents various 

effects of climate change, and how those effects will impact transportation system 

management and operations. Also presented are presents various options for agencies to 

assess the vulnerabilities of transportation systems and proposed changes to make 

transportation operations more resilient to climate change. 

17. . Key Words

Climate change, transportation systems 

operations, transportation system operations

18. Distribution Statement

No restrictions. 

19. Security Classif.(of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

42

22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
Page ii

Table of Contents

1. Introduction ..............................................................................................................................................1

2. Climate Change Effects to Transportation System Management and Operations...................................2

2.1. Effects Associated with Climate Trends............................................................................................3

2.1.1. Air Temperature..........................................................................................................................3

2.1.2. Precipitation................................................................................................................................8

2.1.3. Coastal Effects...........................................................................................................................11

2.1.4. Human Health Effects ...............................................................................................................12

2.1.5. Ecological Effects.......................................................................................................................12

2.2. Impacts Associated with Climate Events .........................................................................................13

2.2.1. Air Temperature Events.............................................................................................................13

2.2.2. Precipitation Events ..................................................................................................................13

2.2.3. Storms and Coastal Flooding ....................................................................................................13

2.2.4. Wildfires....................................................................................................................................14

2.2.5. Landslides..................................................................................................................................14

2.2.6. Dust Storms...............................................................................................................................14

2.3. Climate Change Effects in the Arctic (Alaska)..................................................................................14

2.3.1. Air Temperature........................................................................................................................14

2.3.2. Precipitation..............................................................................................................................14

2.3.3. Ice, Snow Cover, and Permafrost..............................................................................................15

3. Impact of Climate Change Effects on Transportation System Management and Operating Agencies.15

3.1. Increased System Maintenance Needs............................................................................................15

3.2. Changes to System Operations Practices and Strategies.................................................................19

3.3. Changing Travel Behavior ................................................................................................................20

3.4. Changes to Freight Transportation ..................................................................................................22

4. Agency Considerations for Assessing Vulnerability of Transportation Systems and Making O&M 

Climate-Resilient.........................................................................................................................................24

4.1 Increasing capability to manage more frequent and more severe climate events..........................24

4.2 Planning for Operations in an uncertain future................................................................................25

5. Conclusions.............................................................................................................................................26

6. References ..............................................................................................................................................27

Appendix A – Climate Change Impact Tables .............................................................................................30
Page 1

1. Introduction

Adaptation to climate change is a topic of recent and great interest in the transportation community. 

The US DOT Policy Statement on climate change adaptation (USDOT, 2011) states the following:

The United States Department of Transportation (DOT) shall integrate consideration of climate 

change impacts and adaptation into the planning, operations, policies, and programs of DOT in 

order to ensure that taxpayer resources are invested wisely and that transportation 

infrastructure, services and operations remain effective in current and future climate conditions. 

The climate is changing and the transportation sector needs to prepare for its impacts. Through 

climate change adaptation efforts, the transportation sector can adjust to future changes, 

minimize negative effects and take advantage of new opportunities.

FHWA’ s Sustainable Transport and Climate Change Team, under the Office of Planning, Environment, 

and Realty, Office of Natural and Human Environment1 has been identifying climate change issues faced 

by State DOTs and Metropolitan Planning Organizations (MPOs), conducting workshops and peer 

exchanges on this topic and developing guidelines and tools to address their concerns. The USDOT 

Climate Change Clearinghouse (USDOT, 2012) is another important source of information on issues 

faced by agencies related to climate change. In June 2011, Transportation Research Board (TRB)

published a research circular (TRB, 2011) assessing the state of the practice of adaptation strategies 

being considered by transportation agencies. All of these resources provide an emerging picture of the 

changes required at an agency level to address the challenges posed by climate change. 

One of the gaps in the currently available literature and guidance is an assessment of how systems 

operations and maintenance adapt to climate change. The challenges posed by climate change to 

infrastructure design and long-term land-use planning are more easily described than how an agency 

needs to adapt their day to day operations strategy given the varied nature of evolving climate and 

travelers’ responses to changing climate. 

This paper addresses the “services and operations” portion of the above USDOT policy statement, 

highlighting potential issues, challenges, and approaches for State DOTs and local operating agencies to 

consider under shifting climate-related conditions. The scope of operations in this paper is limited to 

surface transportation activities and does not include air or water-borne transportation. 

For the purposes of this paper, “effects” refer to climate change issues and “impacts” are the 

consequences that climate change effects have on transportation.

The paper includes the following sections:

• Section 2 provides an overview of climate change effects that will impact transportation in the 

U.S.

 1 http://www.fhwa.dot.gov/environment/climate_change/
Page 2

Exhibit 1 – Climate Change Scenarios

Changes in future climate are determined from the output of general circulation models 

(GCMs). GCMs are complex models that simulate atmosphere, ocean, and land processes. 

They typically project changes in temperature and precipitation, from which changes in 

related parameters (e.g., incidence of wildfires, changes in water quality) are derived. 

GCMs generally have relatively low spatial resolution, on the order of 400 to 125 km (250 

to 80 mi), so a technique called downscaling is used to obtain projections on regional and 

local scales. 

GCMs simulate changes in climate under scenarios of future conditions. Scenarios are not 

predictions or forecasts of future events. Instead, a scenario represents a possible version 

of the future (IPCC, 2000). Scenarios are used when reliable projections of future 

conditions are not available, as is the case for climate change. They attempt to constrain 

the range of plausible future conditions, based on socio-economic variables and trends in 

global emissions of greenhouse gases and aerosols. Characteristics of the four basic 

scenario families used for current GCM projections are listed in Table 2.6 (IPCC, 2000). At 

present, it is not possible to predict which scenario is most likely to occur in the 21st

century. As a result, GCMs are typically run under scenarios of high (A2) and low (B1) 

greenhouse gas emissions to provide a representative distribution of possible future 

climate conditions.

Summary of Climate Scenarios. [Adapted from IPCC, 2000]

Scenario Economic 

Development

Global 

Population

Technology 

Changes Theme

A1 Very rapid

Peaks around 

mid-21st century 

and declines 

thereafter

Rapid 

introduction of 

new and more 

efficient 

technologies

Convergence 

among regions; 

increased cultural 

and social 

interactions

A2 Regionally 

oriented

Continuously 

increasing

Slower and 

more 

fragmented 

than A1, B1, and 

B2

Self-reliance and 

preservation of 

local identities

B1

Rapid change 

toward 

service and 

information 

economy

Same as A1

Introduction of 

clean and 

resourceefficient 

technologies

Global solutions to 

economic, social, 

and environmental 

sustainability

B2

Intermediate 

levels of 

economic 

development

Continuously 

increasing, but 

not as fast as A2

Less rapid and 

more diverse 

changes than A1 

and B1

Local solutions to 

economic, social, 

and environmental 

sustainability

• Section 3 describes the impacts of the expected climate change effects on systems 

management and operations

• Section 4 identifies considerations and approaches to make systems management and 

operations more climate-resilient. 

2. Climate Change Effects to Transportation System Management and 

Operations

This section provides an 

overview of the expected 

climate change effects that will 

impact the transportation 

community, focusing on impacts 

that will require operational 

responses as opposed to longterm behavioral or planning level 

responses. The adjacent exhibit 

(Exhibit 1) illustrates how 

changes in future climate are 

determined through the use of 

General Circulation Models 

under a variety of scenarios. 

The relevant climate change 

effects are separated into two 

general categories based on 

whether the effect is part of a 

climate trend (e.g., increasing 

annual average air 

temperatures) or it is associated 

with a distinct climate event

(e.g., storm, flood, drought, heat 

wave), as these different 

categories of effects will 

necessitate different types of 

operational responses by 

transportation agencies

Tables A.1 and A.2 list the full 

range of relevant climate change effects for the transportation sector in the continental U.S. (CONUS) 

and Hawaii for the 21st century, along with the affected regions and projected date range for the effect 

to occur. Effects for Alaska are listed separately in Table A.3, since they are distinct in many ways from 

analogous effects in the tropics (Hawaii) and mid-latitudes (CONUS). When available, the associated 
Page 3

certainty of an effect is also specified in Tables A.1-A.3. Certainty is designated using terms defined by 

the Intergovernmental Panel on Climate Change (IPCC) in their Fourth Assessment Report (Le Treut et 

al., 2007); these terms are listed in Table A.4 and Table A.5 in Appendix A. For simplicity, sources of the 

climate change effect information in this section were limited to summary reports, such as those from 

the IPCC, the Climate Change Science Program (CCSP), and U.S. Global Climate Change Research 

Program (USGCRP). Much of the data in the cited reports originated from the 2007 IPCC report; the next 

IPCC report is expected in 2013-14. The following sections highlight some of key climate trends and 

event-related effects of climate change.

2.1. Effects Associated with Climate Trends

The following effects are associated with climate trends leading to changing conditions over time. 

2.1.1. Air Temperature

Rising concentrations of greenhouse gases in the global atmosphere during the 21st century are 

expected to cause a net warming of the Earth’s surface, leading to higher average air temperatures. In

general, GCMs run under scenarios of high greenhouse gas emissions (A2) project larger increases in air 

temperatures than scenarios of low emissions (B1). Furthermore, the magnitude of increases in air

temperatures is projected to be greater toward the end of the 21st century. This acceleration in 

warming is a result of the cumulative effect of increasing levels of long-lived greenhouse gases in the 

atmosphere.

Since 1900, the global average temperature has increased by about 1.5 degrees Fahrenheit (USGCRP,

2009). GCMs indicate that average annual air temperatures across all of North America, including the 

CONUS and Alaska, will increase steadily during the 21st century. In fact, by 2039, annual average 

temperatures are anticipated to be above the range of current natural variability (Christensen et al., 

2007). Projections of annual average temperatures (Figure 2.1) suggest that increases will be in the 

range of 1 to 3°C (1.8 to 5.4°F) by 2039 (Christensen et al., 2007). These changes will vary by season, 

with the largest increases expected to occur across the northern regions during the winter and the 

largest increases expected to occur in the Southwest during the summer (Christensen et al., 2007). The 

magnitude of average temperature increases during the summer is projected to be 3 to 5°C (5.4 to 9°F) 

across most of North America by the end of the 21st century (Christensen et al., 2007). Air temperature 

changes near the coasts are expected to show less seasonal variability due to warming of the oceans 

associated with climate change (Christensen et al., 2007). 

Regional trends of annual and seasonal air temperatures in the CONUS are consistent with continental 

trends (Figures 2-2 and 2-3). Annual average air temperatures across the CONUS are expected to rise 7 

to 11°F under the A2 (high) scenario and approximately 4 to 6.5°F under the B1 (low) scenario by 2100, 

and warming will be greatest during the summer (FHWA, 2010). By 2050, average air temperatures are 

projected to increase 2.5 to 4°F in winter and 1.5 to 3.5°F in summer in the Northeast (USGCRP, 2009)

and 2.7°F ± 1.8°F in the Gulf Coast region (CCSP, 2008). In the Southeast and the southern and central 

Great Plains, increases in average air temperatures during the summer are projected to be larger than 

those in winter (USGCRP, 2009). In some areas of the Southwest, increases in air temperature during 
Page 4

the summer are expected to be larger than annual average increases, and they will be exacerbated by 

localized urban heat island effects (USGCRP, 2009). Due to the increases in air temperatures across the 

U.S., electricity demand for air conditioning in most North American cities is anticipated to increase 

considerably in the 21st century, in order to cool homes and indoor work and recreation spaces (Field et 

al., 2007).
Page 5

 

 

Figure 2.1. Changes in annual average air temperature relative to 1901-1950 averages for Alaska (ALA), Western North America (WNA), 

Central North America (CAN), and Eastern North America (ENA): observed for 1906-2005 (black line), simulated by climate models for 1906-

2005 (red shading), and projected by climate models for 2001-2100 (orange envelope) under the A1B (moderate) scenario. The colored bars 

at the end of the orange envelope represent the range of projected changes for 2091-2100 under the B1 (low) scenario (blue), the A1B 

(moderate) scenario (orange), and the A2 (high) scenario (red). [Adapted from Christensen et al., 2007] 
Page 6

Figure 2.2. Projected changes in annual average air temperature for six regions of the U.S., Alaska, Hawaii, and the Caribbean through 2100, 

relative to 1961-1979 averages, compiled using the A2 (high) and B1 (low) scenarios. [Adapted from ICF International, 2010] 
Page 7

Figure 2.3. Projected changes in winter average air temperature for six regions of the U.S., Alaska, Hawaii, and the Caribbean through 2100, 

relative to 1961-1979 averages, compiled using the A2 (high) and B1 (low) scenarios. [Adapted from ICF International, 2010] 
Page 8

2.1.2. Precipitation

Higher air temperatures associated with rising concentrations of greenhouse gases are expected to 

increase the amount of water vapor in the atmosphere, leading to overall increases in global 

precipitation during the 21st century. It is important to note that GCM projections of temperature 

changes for a given region are generally consistent in sign and magnitude, but precipitation projections

can vary widely across models due to the difficulty in simulating the myriad of factors that influence 

precipitation frequency, duration, and intensity. An additional complicating factor is that precipitation

in the U.S. varies naturally on seasonal, annual, and inter-annual time scales. In model simulations, any 

precipitation changes associated with future climate change are overlaid on this natural variability, 

making it difficult for GCMs to resolve contributions from natural and anthropogenic influences. The 

result is increased uncertainty in expected precipitation changes associated with future climate change

as compared to projections for temperature.

Figures 2.4 and 2.5 illustrate the expected range of regional changes in winter and summer precipitation 

in the U.S. through 2100. Model projections indicate that annual average precipitation will increase 

across the northern CONUS and decrease in the southern CONUS, particularly in the Southwest 

(Christensen et al., 2007; USGCRP, 2009). Overlaid on this annual change will be seasonal variations, 

with most of the increases in precipitation in the northern CONUS and most of the decreases in 

precipitation in the southern CONUS expected to occur in the winter and spring (ICF International, 

2010). 

Associated with the increasing air temperatures, snow season length and snow depth are projected to 

decrease across most of North America (Christensen et al., 2007). Figure 2.6 depicts projected changes

in percent snow depth in North America during March in 2041-2070. The rain/snow line is expected to 

shift northward and to higher elevations, causing more winter precipitation to fall as rain and less as 

snow (ICF International, 2010). Furthermore, less overall snowfall and earlier snowmelt in the spring will 

lead to a general decrease in snow depth across snow-covered regions of the U.S. (Christensen et al., 

2007), particularly in the Rocky Mountains. 
Page 9

Figure 2.4. Projected changes in winter average precipitation for six regions of the U.S., Alaska, Hawaii, and the Caribbean through 2100, 

relative to 1961-1979 averages, compiled using the A2 (high) and B1 (low) scenarios. [Adapted from ICF International, 2010] 
Page 10

Figure 2.5. Projected changes in annual summer precipitation for six regions of the U.S., Alaska, Hawaii, and the Caribbean through 2100, 

relative to 1961-1979 averages, compiled using the A2 (high) and B1 (low) scenarios. [Adapted from ICF International, 2010] 
Page 11

Figure 2.6. Projected change in percent snow depth (DS) in March for 2041-2070, relative to 1961-

1990 averages, under the A2 (high) scenario. [Adapted from Christensen et al., 2007]

2.1.3. Coastal Effects

Climate change is projected to cause a rise in global sea levels of between 0.18 m to 0.59 m (7.1 in to 

23.2 in) by 2099 due to thermal expansion of ocean water and melting of glaciers, though the rise will 

not be uniform(TRB, 2008). This rise in sea level will impact the Atlantic and Pacific coasts of the U.S., 

leading to coastal inundation and accelerated rates of coastal erosion (Field et al., 2007). Coastal 

erosion is also expected to be exacerbated by reductions in the extent and duration of sea ice, which will 

allow for more open water during the winter storm season (Field et al., 2007). 

Along the Gulf Coast, sea level is projected to increase by at least 1 ft and up to 6 to 7 ft in some 

locations, such as central and western Louisiana and eastern Texas, where subsidence rates are highest

(CCSP, 2008). In the Northeast, model predictions under a high (A2) scenario suggest that sea level will 
Page 12

rise along the Atlantic coast more than the global average, leading to severe coastal flooding (USGCRP, 

2009). For example, what is currently considered a 100-year flood event may occur twice as often by 

2050 and up to ten times as often (an average of once per decade) by 2099 (USGCRP, 2009). In the 

Northwest, the south Puget Sound region is particularly vulnerable to sea level rise and increasing 

coastal erosion, including the cities of Olympia, Tacoma, and Seattle in Washington State (USGCRP, 

2009). A potential increase in the number of landslides on coastal bluffs in the Northwest is also a 

concern, associated with more saturated soils from increased precipitation (USGCRP, 2009). 

2.1.4. Human Health Effects

It is projected that U.S. residents over the age of 65 will represent 20% of the U.S. population by 2030. 

This population shift along with projected increases in the frequency, intensity, and duration of 

heatwaves suggests a future increase in heat-related deaths, particularly in highly developed areas 

where the urban heat island effect is present (USCCSP SAP 4.6, 2008). A warmer climate in the U.S. is 

also expected to make conditions more favorable for increases in pollen, some air pollutants, and Lyme 

disease, thereby increasing risks to human health. Higher temperatures are generally favorable for the 

expansion of tick distributions and greater abundance of vector-borne diseases like Lyme disease 

(USCCSP SAP 4.6, 2008). Rising air temperatures and high atmospheric carbon dioxide (CO2) 

concentrations are anticipated to increase pollen concentrations in the CONUS (Field et al., 2007). 

Higher air temperatures may also increase concentrations of tropospheric (surface-level) ozone (O3) and 

non-volatile fine particulate matter (PM2.5), due to increased rates of associated gas-phase reactions 

(Field et al., 2007), which in turn may exacerbate and intensify the occurrence of respiratory illness, such 

as asthma (USCCSP SAP 4.6, 2008). In addition, as air temperatures increase, trees and plants emit more 

O3 precursors, such as isoprene, which will also enhance production rates of O3 (Field et al., 2007). By 

2050, daily average ozone levels are projected to increase 3.7 parts per billion by volume (ppb) in the 

eastern U.S., and the number of summer days that exceed the 8-hour O3 regulatory standard is expected 

to increase by 68% (Field et al., 2007). 

2.1.5. Ecological Effects

Climate change may also have significant impacts on ecosystems in the CONUS. Model projections 

indicate that the growing season will expand during the 21st century, with earlier spring thawing and 

later fall freezing (Field et al., 2007). Less snow cover and more winter precipitation falling as rain will 

increase runoff, lengthen the erosion season, and enhance inland erosion (Field et al., 2007). Along the 

Atlantic and Pacific coasts, the salinity of estuaries, coastal wetlands, and tidal rivers is expected to 

increase due to saltwater intrusion, which will damage coastal ecosystems and possibly shift them 

farther inland (USGCRP, 2009). Climate change is projected to expand the geographic range of invasive 

species, which alter the structure and composition of ecosystems. Non-native insects that have 

expanded their ranges in the U.S. include the Asian long-horned beetle, hemlock woolly adelgid, the 

common European pine shoot beetle, and the emerald ash borer. Non-native invasive plant species 

have altered fire regimes in the western U.S.; cheatgrass is an invasive species now common in the 

Intermountain West, which has changed the fuel complex, increased fire frequency, and reduced habitat 

within this region (USCCSP SAP 4.4, 2008).
Page 13

2.2. Impacts Associated with Climate Events

The following impacts are associated with events that are expected to occur as a result of changing 

climate trends. 

2.2.1. Air Temperature Events

Rising air temperatures in the U.S. during the 21st century mentioned in Section 2.1.1 are expected to 

cause increased incidences of heat waves and extreme temperature events. The frequency and 

duration of warm extremes are projected to increase across North America (Christensen et al., 2007). In 

the CONUS, the magnitude and duration of severe heat waves, characterized by stagnant, warm air 

masses and consecutive nights with high minimum temperatures, are predicted to increase in locations 

where heat waves already occur (Field et al., 2007). In the Gulf Coast region, the number of very warm 

days (high temperatures >90°F) is expected to increase significantly, and by 2050, there will be a 50% 

probability of 21 days per year with high temperatures ≥100°F (CCSP, 2008). Similarly, in the Northeast, 

GCMs run under the A2 (high) emissions scenario project that some cities, such as Hartford, CT, and 

Philadelphia, PA, will average almost 30 days per year with high temperatures >100°F (USGCRP, 2009). 

In the Midwest, the frequency, severity, and duration of heat waves are expected to increase, and by 

2100, GCMs run under the A2 (high) emissions scenario project that severe heat waves could occur once 

every two years (USGCRP, 2009). 

2.2.2. Precipitation Events

Changes in precipitation patterns associated with climate change will lead to changes in the incidences 

of extreme precipitation events and related phenomena, including floods and droughts. Extreme 

precipitation events, such as thunderstorms and heavy downpours, are projected to increase in 

frequency and intensity (Meehl et al., 2007; ICF International, 2010). Across the CONUS, the probability 

of a heavy downpour occurring in a given year is expected to increase from 5% to 20-75% by 2100 (ICF 

International, 2010). The intensity of individual rainfall events is projected to increase in the Gulf Coast 

region during the 21st century (CCSP, 2008). 

In the Northeast, GCMs run under the A2 (high) emissions scenario project that 1-3 month droughts will 

occur every summer in the Catskill and Adirondack Mountains of New York and across New England 

(USGCRP, 2009). The frequency, duration, and intensity of droughts are expected to increase in the 

Southeast, Midwest, and Southwest as well (USGCRP, 2009). In the Northwest, more precipitation 

falling as rain and not snow is anticipated to cause winter flooding on the west side of the Cascade 

Mountains (USGCRP, 2009).

2.2.3. Storms and Coastal Flooding

Changes in atmospheric circulation, in conjunction with increases in air temperature and altered 

precipitation patterns due to climate change, will affect the development of storms, including tropical 

cyclones (hurricanes and tropical storms) and extra-tropical cyclones (large mid-latitude snowstorms 

and rainstorms). Climate change is expected to shift the jet stream over the U.S. northward (ICF 

International, 2010), resulting in a slight shift in mid-latitude extra-tropical cyclone storm tracks toward 
Page 14

the North Pole (Christensen et al., 2007). The intensity of extra-tropical cyclones is anticipated to 

increase, but they will occur less frequently (Meehl et al., 2007).

Trends for tropical cyclones are less clear. As surface water temperatures in the Atlantic Ocean and Gulf 

of Mexico increase due to climate change, the intensity of hurricanes is expected to increase, possibly by 

10% (CCSP, 2008). Some GCMs predict that hurricanes’ peak wind speeds and rainfall intensity will 

increase (Meehl et al., 2007). Potentially stronger tropical cyclones combined with rising sea level are 

expected to result in higher storm surge and more severe coastal flooding (Field et al., 2007; USGCRP, 

2009).

2.2.4. Wildfires

Warmer and drier conditions in the 21st century associated with climate change will increase the 

potential for wildfires. Across the CONUS, higher air temperatures during the summer are projected to 

increase the risk of fire ignition by 10-30% by 2100 (Field et al., 2007). In the Northwest, earlier 

mountain snowmelt in the spring combined with higher air temperatures are anticipated to create dry 

conditions during the summer that will increase the risk of forest fires (USGCRP, 2009).

2.2.5. Landslides

Increased heavy precipitation in the winter and spring suggest an increase in soil saturation and a 

compromise in slope stability, which is projected to cause an increased occurrence of landslides and/or 

mudslides. In coastal areas, bluff landslides will be exacerbated by the rise in sea level (USGCRP, 2009).

2.2.6. Dust Storms

Temperature and precipitation changes are projected to decrease vegetation cover, which protects the 

ground from erosion. As a result, it is suggested the occurrence of dust storms will increase (USCCSP 

SAP 4.3, 2008).

2.3. Climate Change Effects in the Arctic (Alaska)

2.3.1. Air Temperature

Air temperatures in Alaska are expected to increase throughout the 21st century, but at a faster rate 

than for the CONUS. Model projections indicate that the annual average warming in Alaska will exceed 

the global mean warming. The largest temperature increases are expected during the winter over 

northern Alaska, due to the positive feedback from reduced snow cover (Christensen et al., 2007) 

(Figure 2.3). The magnitude of warming is projected to vary from 7°C (12.6°F) in winter to 2°C (3.6°F) in 

summer by 2050 (Christensen et al., 2007; USGCRP, 2009).

2.3.2. Precipitation

Models are consistent in predicting an increase in annual average precipitation in Alaska, with most of 

the increase occurring during the winter months (Christensen et al., 2007; ICF International, 2010). As 

air temperatures rise, the ratio of rain to snow is expected to increase, so more precipitation should fall 

as rain and less as snow, particularly in locations in Alaska where average air temperatures are currently 
Page 15

close to freezing (Anisimov et al., 2007). Changes in the frequency of extreme temperature and 

precipitation events in the Arctic are uncertain, but projections indicate that very warm and wet winters 

and summers will become more frequent in the 21st century (Christensen et al., 2007). 

2.3.3. Ice, Snow Cover, and Permafrost

Increasing air temperatures will have a profound effect on ice, snow cover, and permafrost in Alaska. 

Recent observations suggest that higher temperatures are already causing earlier spring snowmelt, 

reduced sea ice, widespread glacier retreat, and permafrost warming in Alaska (USGCRP, 2009). The 

extent and thickness of Arctic sea ice is expected to continue to decrease, with reductions of 22 to 33% 

in the extent of annually averaged sea ice projected by 2080-2100 (Anisimov et al., 2007; Christensen et 

al., 2007). Most of the reduction in sea ice is expected during the summer (Anisimov et al., 2007). 

Additional loss of snow cover on land is also projected (Figure 2.3), with reductions in snow residence 

times expected to be greatest in spring (Anisimov et al., 2007). Warmer conditions are anticipated to 

shrink the extent of terrain underlain by permafrost. By 2050, models project that the permafrost area 

in the Northern Hemisphere will decrease by 20 to 35%, due to thawing of permafrost in both 

discontinuous (10 to 90% of land frozen) and continuous (90 to 100% of land frozen) zones (Anisimov et 

al, 2007). 

3. Impact of Climate Change Effects on Transportation System Management 

and Operating Agencies

It is clear that many of the climate change effects listed in Section 2 require long-term changes to how 

transportation infrastructure is planned, designed, and constructed. Additionally, land-use planning and 

travel behavior modifications are important components of adaptation strategies. From a systems 

management and operations perspective, agencies face an uncertain future with respect to how they 

maintain, operate, and plan for the future. This section discusses the impact of climate change on 

transportation and systems management operations. 

3.1. Increased System Maintenance Needs

Given the climate change effects listed in Section 2, specifically those related to increases in average air 

temperatures and shifts of the rain/snow line during the winter, transportation agencies will likely need 

to adapt by making changes to system maintenance. These changes could affect winter maintenance 

operations, require diversion to more resilient alternate routes, and prompt the deployment of “quick 

maintenance” patrols to address potentially more frequent potholes and buckling issues. Climate 

change effects to system maintenance needs are presented in Table 1.
Page 16

Table 1. Climate Change Impacts and Potential Responses for System Maintenance Needs

Climate Change Effects Climate Change Impacts System Maintenance Response

Climate Trends Impacts

Shifting rain/snow line 

Fewer snow/ice precipitation events Reduced need for winter maintenance 

operations resources and staff

Less snowfall in areas that were 

previously impassable due to high and 

frequent snowfall

Potential for increased winter maintenance 

operations on routes currently inaccessible in 

winter

Increased snowmelt/rain during the 

winter season increases the likelihood 

of flooding, which will generally affect 

specific roadways and locations, as 

opposed to the whole network

Shift in resources from winter maintenance to 

winter flooding monitoring and traveler 

information

Temperatures in some areas may shift 

to or more frequently hover at the 

freezing point, increasing the probability 

of ice precipitation instead of snow 

Shift in resources from snow to ice 

management

Long-term shifting of snow/ice 

precipitation necessitates reassessment 

of winter maintenance needs

Monitoring trends to identify and forecast 

trends of increasing or decreasing snow/ice and 

frequency of extreme precipitation events

Longer construction season due to 

higher temperatures, fewer days with 

temperatures below freezing, and less 

snow/ice precipitation

Altered construction and maintenance 

schedules

Changes in freeze/thaw 

cycle

Potential for longer duration and/or 

shifting of freeze/thaw period

Increased staff and resources to monitor 

vulnerable areas to post seasonal weight 

restrictions and make repairs. 

Increased frequency, 

duration and intensity 

of droughts; increase in 

average air 

temperature

Roadside vegetation dies off Changes to vegetation management activities

Increased probability of wildfires

Increased staff and resources to monitor 

vulnerable areas and provide traveler 

information

Climate Event Impacts

Increased coastal and 

inland flooding; 

increases in intense 

precipitation events

Greater frequency of flooded, blocked 

(e.g., trees, landslides), damaged, and 

washed out roads

Mandatory diversion to more robust alternate 

routes, reducing route options/redundancy

Increased staff and resources to monitor 

vulnerable routes and provide traveler 

information

Increase in magnitude 

and duration of severe 

heat waves

Greater risk of structural damage to 

bridge joints and pavement, e.g., 

buckling or rutting

Mandatory diversion, particularly for freight, to 

more robust alternate routes

Deploy “quick maintenance” patrols to address 

potholes and buckling issues

Higher temperatures may inhibit 

construction activities during certain 

months, or times of day

Altered construction and maintenance 

schedules
Page 17

Climate Change Effects Climate Change Impacts System Maintenance Response

Increase in dust storms Greater frequency of reduced visibility 

conditions

Increased staff and resources to monitor 

vulnerable routes and provide traveler 

information

Increases in average air temperature and reduced snowfall have the potential to impact greatly 

operations required for winter maintenance. Currently, 70% of the nation’s roads are in regions that 

receive over 5 in of annual average snowfall, requiring the expenditure of over $2.3 billion per year by 

state and local agencies for winter maintenance activities (FHWA, 2012). Additional millions of dollars 

are spent on infrastructure to repair damages caused by snow and ice (FHWA, 2012). 

Multiple impacts highlighted in Section 2 could reduce the need for winter maintenance, most notably 

the increase in average air temperatures with the largest magnitude of warming in northern regions 

during winter and the general shifting of the rain/snow line north and to higher altitudes. For some 

areas, these impacts might indicate fewer days below freezing and thus reduced incidence of 

precipitation causing snow or ice conditions. For these areas, there may be a reduced need for 

resources to be dedicated to winter maintenance operations. However, there may also be opportunities 

to shift winter maintenance operations to areas that currently have seasonal closures, but will be easier 

to maintain with reduced snowfall under a changing climate.

Similarly, increases in average air temperature that cause the rain/snow line to shift north are likely to 

also influence subgrade freeze/thaw cycles. While a frozen subgrade provides a solid foundation for 

heavy vehicles on roadways, heavy vehicles traveling on a roadway with a poor subgrade can cause 

potholes and rutting that may require additional system maintenance for repairs. Alternatively, 

imposing weight restrictions during the spring freeze/thaw period may help ease this issue. Either way, 

additional staff and resources may be required to monitor the subgrade temperatures and pavements to 

know when weight restrictions should be imposed and repairs are required.

Furthermore, with the potential for increased frequency and intensity of extreme precipitation events, 

added winter maintenance operations resources may be imperative to maintain functionality of the 

transportation network. Winter storm disasters alone have caused over $29 billion in damages 

(adjusted for inflation) since 1980 (NOAA, 2012), and increases in intensity of extreme precipitation 

events may cause greater damages in the future. Winter flooding is projected in the Northwest due to 

more precipitation falling as rain and not snow, which would alter the response required from system 

maintenance personnel from winter maintenance operations to system monitoring and traveler 

information regarding flooding and closures.

Although severe damages from winter storms are often caused by ice damage to trees and power lines 

requiring cleanup and repairs, many winter storms produce only snowfall, which causes no significant 

damages, but simply impedes mobility on the transportation network until routes can be cleared. 

Increases in average air temperature may affect the type of precipitation that occurs in an area as the 
Page 18

rain/snow line moves northward and to higher elevations, and the frequency of ice storms for particular 

regions may also shift northward.

Winter maintenance operations are already difficult to predict, since snowfall is quite variable - one 

year, 6 ft of snow might fall in a given location, and the next year no snow might fall at all. Climate 

change effects may influence trends overall such that snowfall extremes are more pronounced from 

year to year, or that the annual average amount of snow and ice precipitation is either reduced or 

increased for an area. Signs of changing trends must be monitored by transportation agencies, as they 

could severely impact winter operations of surface transportation. Necessarily, agencies may struggle to 

justify spending on resources and staff that remain unused or underutilized from year to year, and 

therefore be left unprepared for major snow events that occur on a less frequent basis.

A recurring consequence of many aforementioned climate change effects might be mandatory diversion 

to more robust alternate routes. This requirement might affect routes that traverse areas that are more 

prone to flooding due to sea level rise or increased precipitation, for example, or that contain lower 

quality pavements that are more susceptible to warmer temperatures. In both cases, transportation 

agencies will have to monitor vulnerable routes to provide traveler information via dynamic message 

signing, websites, or radio, for example, as well as have staff on hand to deploy signage and physically 

close impacted routes, as necessary. Impacts of warmer temperatures on pavements may require 

diversion of freight traffic more so than passenger traffic, in which case either static or dynamic weight 

restrictions might be imposed on those routes. Today, transportation agencies frequently recommend 

diversion for flooded areas using methods listed above; but with climate change effects, agencies should 

strategically expand their capacity for making these recommendations by deploying monitoring devices 

for roadways that are likely to be most affected. 

Similarly, increases in magnitude and duration of severe heat waves are likely to increase issues related 

to potholes and buckling in pavements. The Iowa DOT reports that in a typical year an average of 

$400,000 is spent to make temporary and permanent repairs related to pavement buckling due to 

thermal expansion forces; costs may be $2000 for a single repair (IDOT, 2012). In particular, this might 

impact pavements that may not have been designed with a changing climate in mind. It is likely that 

warmer regions that experience these severe heat waves will begin incorporating pavement designs 

with increased tolerances for higher temperatures; however, some segments are likely to contain 

historic, lower quality pavement that is more susceptible to potholes and buckling. Transportation 

agencies may find it beneficial to deploy “quick maintenance” patrols for potholes and buckling issues,

especially during extreme high temperature events when the buckling is most likely to occur. These 

“quick maintenance” patrols might operate in a manner similar to freeway service patrols (FSPs), or 

actually be an added service of FSPs. Just as FSPs are deployed on freeways to quickly address and clear 

incidents or stopped vehicles to maintain mobility, “quick maintenance” patrols would be available to 

quickly repair potholes or buckling pavement that is impacting mobility or safety on the roadway. For 

example, during extreme heat events, Virginia DOT puts crews on special alert to be prepared for 

emergency repairs to the state’s roadways (VDOT, 2012).
Page 19

In general, increases in average air temperatures could alter the timing of construction activities

throughout the year, particularly in northern areas where construction activities tend to be more limited 

in the winter (FHWA, 2011). Additionally, increases in the frequency and duration of heat waves could 

shift the timing of construction activities to occur at cooler parts of the day.

Finally, with changes to precipitation and temperature, roadside vegetation is likely to be affected. 

While drier conditions are likely to reduce the need for mowing operations, in general, increases in the 

frequency, duration, and intensity of drought conditions will precipitate the need for new, droughtresistant species that can survive dry conditions and serve as erosion control.

3.2. Changes to System Operations Practices and Strategies

Numerous impacts due to more widespread, higher intensity storms or tropical cyclones will create the 

need for broader disaster and evacuation preparedness. In general, planning for these events will come 

with increased uncertainty, as it pertains to personnel and resources. Likewise, rising sea levels and 

flood risks may increase the need to monitor vulnerable roadways in order to restrict access, given realtime conditions. Additionally, spikes in energy consumption due to warmer temperatures may cause 

localized power outages that could disrupt Traffic Management Centers’ communications. Climate 

change effects to system operations are presented in Table 2.

Table 2. Climate Change Effects to and Potential Responses by System Operations

Climate Change Effects System Operations Response

Climate Event Impacts

Increased recurring coastal and inland flooding; 

rising sea levels

Mandatory diversion to more robust alternate routes 

Increased staff and resources to monitor vulnerable routes 

and provide traveler information

Increase in intensity of tropical cyclones;

increased occurrence of wildfires

Broader preparedness for potential evacuation 

Increased TMC staff and Intelligent Transportation System 

(ITS) resources to provide traveler information during 

evacuations

More frequent disaster preparation, operations, and 

recovery actions 

Climate Trends Impacts

Increase in energy demand for air conditioning

Increased need for more resilient TMC communications and 

backup power to maintain real-time information feeds

Increased inland and coastal flooding might increase the need to monitor a wider and different set of

roadways and restrict access given forecasted or real-time conditions. With higher chances for flooding 

on a greater number of roadways, given more intense precipitation events, for example, there is a

greater need for monitoring of these high-risk flood prone roadways for increased traveler information. 

Numerous examples of weather monitoring exist in which the TMC monitors flood gauges to alert 

travelers to real-time conditions.
Page 20

Regarding hurricanes, increased intensity of storms coupled with rising sea levels will cause greater 

impacts over a broader area given the potential for shifting storm tracks, stimulating the need for a 

widened area for preparedness for evacuations. Thirty-one hurricane events have caused $417 billion 

(adjusted for inflation) in damage in the United States since 1980 (NOAA, 2012); more intense storms 

will likely increase the amount of damage and require faster and more comprehensive responses. This 

includes the need for greater TMC support for traveler information and for ITS to assist motorists during 

an evacuation. Additionally, more frequent disaster preparation, operations, and recovery actions will 

be needed to prepare those who may be impacted by these events. However, because of the likelihood 

of reduced frequency for such storms, there will be increased uncertainty in planning for hurricanes, in 

terms of personnel and resources. Similar actions may be required for inland areas that are impacted by 

flooding due to increased inland flooding, or for areas that are expected to experience increased 

wildfires. 

Finally, with increases in extreme high temperature events and the intensity, frequency, and duration of 

heat waves, there will likely be an increase in energy demand for air conditioning during summer 

months. This could lead to spikes in energy usage that cause local power outages. This prompts the 

need for more resilient TMC communications and backup power in the field to maintain real-time 

information to drivers. 

3.3. Changing Travel Behavior

Climate change effects are likely to affect greatly individuals’ transportation decisions and safety on the 

roadways. For example, because temperature and precipitation can impact decisions to use transit, 

bike, or walk, regional changes could increase or decrease individuals’ motivation to use alternate 

modes. This phenomenon has been investigated in a study on how weather affects Chicago transit 

ridership (Guo, et al., 2007). The data-driven study findings, which are shown in Table 3, showed that 

CTA bus ridership and weekend ridership are more sensitive to extreme weather than rail ridership and 

weekday, respectively, and that some weather conditions like fog or blizzards can increase transit 

ridership (Guo, et al., 2007). The study found that weekend ridership changed more than weekday 

ridership (Guo, et al., 2007). Localized climate change effects could also affect individuals’ routes and 

destinations, as well as exposure to weather-induced hazardous driving conditions. Climate change 

effects and potential responses that might change traveler behavior are presented in Table 4.
Page 21

Table 3. Correlation between Weather Conditions and Chicago Transit Administration (CTA) Bus 

and Train System-wide One-Day Ridership

Weather Condition

Bus Ridership Impact* Rail Ridership Impact*

Low High Low High

Temperature (one degree increase) +700 +1100 +200 +700

Rain (one inch increase) -16,000 -88,000 -5000 -45,000

Snowfall (one inch increase) -10,000 -188,000 Inconsistent/Not 

Significant

Inconsistent/Not 

Significant

Wind (one mph increase) -700 -2700 Negligible Negligible

Fog (moderate) Not significant Not significant +8000 +10,000

*Note: on average, one-million and a half-million rides are taken on the CTA bus and rail systems, 

respectively.

Source: Guo, et al., 2007.

Table 4. Climate Change Effects and Potential Changes in Travel Behavior

Climate Change Effect Changes to Travel Behavior

Climate Event Impacts

Increased exposure to hazardous 

driving conditions (e.g., flooding, 

road surface conditions, smoke 

from wildfires)

Less consistent mode split impacting day-to-day congestion 

and safety issues 

Potential mode shift to/from alternate modes, e.g., using

transit, biking, or walking

Increased TMC monitoring of more reliable routes to 

provide enhanced traveler information

Increased emphasis on carpooling and teleworking to 

reduce impacts to highways

Investigate regional climate change impacts to understand 

how impacts may affect traveler mode and route choice in 

both the short- and long-terms

Climate Trend Impacts

Human health effects

Potential mode shift from alternate modes, e.g., transit, 

biking, or walking

Increased emphasis on carpooling and teleworking to 

reduce impacts to highways

Many of the climate change effects listed in Section 2 will increase individuals’ exposure to hazardous 

driving conditions, which include reduced visibility, flooding, hazardous road surface conditions, 

landslides, and wildfires. All of these effects, individually, are likely to reduce driver safety and increase 

the likelihood for crashes. In addition, it is likely to reduce mobility with increased travel times due to 

the need to drive slower in adverse weather conditions or take alternate routes. 

Clearly, climate change effects will vary by region with some mode shift to alternate, non-driving modes 

occurring in areas with less precipitation or more mild winters, for example; other areas may see mode 

shift to cars if extreme temperatures and increased precipitation occur. These mode shifts could affect 

operations on a day-to-day basis, potentially causing increased congestion and safety issues on 
Page 22

highways for some days and on transit on other days. The relationship between weather and mode 

choice is complicated. Mode shift away from alternate, non-driving modes may also be induced by 

human health effects caused by higher pollen counts and pollution, i.e., higher concentrations of 

tropospheric (surface) ozone and non-volatile particulate matter (PM2.5). Moreover, travelers may avoid 

certain routes that are more vulnerable to climate change effects, e.g., flooding, which could increase 

congestion on more robust alternate routes. In general, transportation agencies should investigate the 

regional climate change effects to understand clearly how these effects may affect traveler mode and 

route choice, and thus affect operations on a day-to-day basis. Some regions may expect alternate, nondriving modes to see increased ridership, overall. In this case, an increased operations focus on traveler 

information and resources for these modes may be in order. Other regions may expect a reduction in 

the use of alternate, non-driving modes. For this case, increased emphasis on carpooling and 

teleworking may be necessary to reduce impacts to highways.

Over time, climate change effects could cause long-term changes in travel behavior. Individuals or 

businesses may choose not to reside in low-lying coastal areas that are more vulnerable to sea level rise 

and increased storm surge associated with coastal storms and hurricanes. Given individuals’ inclination 

to live near the coast despite the risk of hurricanes, it is uncertain whether this inland shift will occur, or 

whether individuals will choose to adapt in place. Regardless, transportation agencies should be 

mindful of the potential for long-term travel shifts, in addition to those that occur in the short-term.

3.4. Changes to Freight Transportation 

In addition to the impacts that climate change effects are expected to have on the transportation 

network as a whole, there might be unique impacts to freight transportation. Multiple climate change 

effects could disrupt inland waterways, impacting freight flows and diverting freight to trucks on 

highways. Roadways with pavements affected by increased temperatures might require dynamic or 

seasonal truck weight or speed restrictions for specific roadways or different regulations for the industry 

as a whole. Expected climate change effects to freight transportation are presented in Table 4.

First, there are several potential climate change effects that might affect shipments on inland 

waterways. Increased occurrence of flooding and drought, coupled with changes in seasonal 

precipitation and river flow patterns, could disrupt freight flows to other inland waterways, such as the 

Mississippi and Ohio Rivers, which might add trucks to highways. Lower water levels in the Great Lakes 

might restrict boat access to ports and shipping channels in that system. The 2007 Commodity Flow 

Survey showed that about 423 million tons of goods (3% of all tonnage) and about 176 billion ton-miles 

(5% of all ton-miles) were carried by water, with the Mississippi River system being the most active 

freight waterway (RITA, 2007). Either high water or low water could affect shipping, but reduced 

reliability of this mode might also encourage a shift to trucks or rail. 
Page 23

Table 5. Climate Change Effects to and Potential Responses by Freight Transportation

Climate Change Effect Freight Transportation Response

Climate Event Impacts

Increased frequency, duration, and intensity of 

droughts; increased coastal and inland flooding 

Restricted access to ports and shipping channels for inland 

waterways 

Mode shift from inland waterways to trucking due to 

reduced reliability

Longer duration and/or shifting of springtime 

freeze/thaw period

Mandatory freight diversion to more robust alternate

routes

Increase in magnitude and duration of severe heat 

waves

Mandatory freight diversion to more robust alternate 

routes or modes

Dynamic or seasonal restrictions for trucks or rail during 

times of high heat, reducing either acceptable speed or 

weight 

Policy and regulation changes to restrict truck size and 

weights for the entire roadway network or specific highway 

classes

Deploy “quick maintenance” patrols to address potholes 

and buckling issues

Increases in average air temperature during the winter are likely to influence subgrade freeze/thaw 

cycles. As mentioned previously, a frozen subgrade provides a solid foundation for heavy vehicles on 

roadways, weight restrictions may be required for roadways with a poor subgrade to prevent potholes 

and rutting. Areas that experience more days above freezing during the winter may have to extend or 

shift the period of time during which weight restrictions are imposed. 

As mentioned previously, the impact of severe heat waves on pavements that were not designed to 

withstand such heat might cause potholes or buckling issues. Although this issue might be addressed in 

the long-term as new pavement designs are implemented to withstand these higher temperatures, in 

the short-term there may be some roadways in which this remains an issue. For these roadways, there 

may be a need to implement dynamic or seasonal restrictions for trucks during times of high heat, 

reducing either acceptable truck speed or weight. Currently, truck weight or size restrictions are not 

uncommon for routes with deficient infrastructure, e.g., bridges and tunnels, and similar restrictions 

might need to be imposed for affected roadways using dynamic or static signage. Alternatively, changes 

to policy and regulations could be implemented to restrict truck size and weights for an entire roadway 

network or for specific highway classes. Such restrictions may also affect freight transport through 

trains. 
Page 24

4. Agency Considerations for Assessing Vulnerability of Transportation 

Systems and Making O&M Climate-Resilient

Sections 2 and 3 illustrated the climate change effects and the potential impacts on operating agencies. 

While adaptation to climate change will involve the entire transportation industry and stakeholders, 

ultimately many of the changes that will occur will manifest themselves as challenges to personal and 

freight mobility and safety. However, the nature of these changes will vary based on the region and the 

agency. While many questions remain, agencies with operational responsibility need to assess 

vulnerabilities for their regions and develop new capabilities and processes to adapt to climate change. 

Primarily, agencies need to increase levels of capability for dealing with climate events and plan for 

emerging changes due to long-term climate trends. Each of these is discussed in more detail. 

4.1 Increasing capability to manage more frequent and more severe climate events

As section 2.2 describes, climate change will manifest itself in a potential increase in the number and 

nature of severe weather events. Established approaches and practices provide the tactics to ensure a 

reasonable level of service to the travelers. However, there is a limit to the effectiveness of these tactics 

based on the type and intensity of the weather events. For more large-scale but rare events, the 

volumes and the geographical and temporal scales of the operational responses overwhelm the 

traditional tactics used for routine events. In these situations, there are short-term behavioral changes 

by travelers (people reacting to mandatory hurricane evacuations, trying new roads, for example) and 

multiple points of system failures. During these events, agencies try to ensure that their systems absorb 

the shocks in a resilient manner without complete failure. With the potential of more frequent and 

more severe events in locations, requires an agile approach to operations. Characteristics in an agency 

for agile emergency transportation operations may include:

Increased and flexible monitoring systems - Most operations adaptation actions rely on improved 

situational awareness at an operating agency for improved monitoring of flash floods, bridge scour, road 

weather conditions, landslides, etc. Traditionally, fixed detection infrastructure has been the dominant 

approach to collect situational data. The challenge posed by climate change is that potentially, a greater 

and different set of locations will need to be monitored over time. While monitoring using fixed 

infrastructure will continue to play an important role, it is unlikely that an agency can greatly increase 

the coverage of such sensors. Mobile observations promise to fill that coverage gap for operating 

agencies, from agency fleet vehicles (such as maintenance trucks) or from private sector data. Another 

source is crowd-sourced data directly from the traveling public. Emerging approaches using social media 

during disaster and even routine weather events promise to greatly increase the coverage and 

situational awareness of the operating agency.

Integration of sophisticated weather information at transportation operations centers – Better decisionmaking during weather events requires not only understanding of the current conditions but also the 

forecast conditions. Precipitation start times, intensity, and types are important determinants in the 

tactics used for responses. Sophisticated weather forecasting models are constantly being refined to 

provide transportation-specific forecasts including road weather conditions at the right times and 
Page 25

geographic scales. However, integration of such data in TMC is both hampered by the lack of awareness 

of the existence of such tools, and the difficulty in interpreting the forecasts to make operational 

decisions. 

Greater intra and inter-agency cooperation - Transportation operations in recent years is truly a 

collaborative activity involving multiple agencies and jurisdictions. Larger events today involve activation 

of multi-agency emergency operations centers (EOCs). Current levels of capabilities must continue to 

grow to deal with the anticipated impacts. 

Rapid mobilization and deployment teams – One of the biggest challenges to operations is the multiple 

points of system failures that exist during weather events. Especially for flash flooding and other 

impacts with very short lead times, the ability to rapidly deploy operational personnel for site 

management, maintenance, debris removal, and other recovery efforts are critical. 

Flexible resource allocations – Greater variability in the type, nature and intensity of events also poses a 

unique challenge to budget resources. While this is easier said than done in an agency framework, static 

or silo-ed resource allocation approaches for operations might be over-funded in one year and under in 

others. Different needs between winter seasons might change the mix of how resources are allocated 

between jurisdictions. 

Cross-training of staff - Since a greater number of events are expected and it is unlikely that staffing 

levels are going to increase at agencies, cross-training of transportation agency staff in emergency 

transportation operations becomes critical. 

Training for unusual events - While still related to training, climate change is going to force agencies to 

respond to conditions that either occur very rarely or have never occurred in their regions. Training 

programs for emergency transportation operations need to focus on what would be considered unusual 

events in regions. 

4.2 Planning for Operations in an uncertain future

The major challenge to agencies is how to plan for operations an uncertain future in a fiscally 

responsible manner. The relationship between the probability of an impact and the severity of impact 

versus the cost of investment continues be a difficult equation for agencies to solve. Given the latency 

from planning to implementation inherent in transportation operations (i.e., future operations are 

dependent on plans being considered today), there is an urgency to include climate change 

considerations in transportation plans today. System Operations historically has been a reactive 

industry. Often, a disaster provides the impetus for various operational capability improvements in a 

region. However, with diminishing fiscal constraints and a higher expectation from the traveling public, 

agencies no longer can afford to be reactive, and they need to assess actively how their systems are 

vulnerable to climate change. 

Recent guidance and best practices are starting to emerge for planning for operations with an emphasis 

on system performance and driven by regional objectives. Driven by policy objectives such as 

congestion, safety, economic competitiveness, agencies are starting to better integrate operations into 
Page 26

the planning process. Into this paradigm of objective-driven performance-based planning, climate 

change considerations have to be included. While many questions remain, two main actions are worth 

investigation as part of planning for operations efforts

Introducing risk assessment in transportation operations planning – Risks are an inherent part of 

transportation planning. However, assessing the risk posed by climate change to operations is new to 

the field. Climate change risks vary across regions and times, they vary in scale of impacts, and there is 

inherent natural and modeling uncertainty in future climate scenarios. The assessment approaches may 

vary from qualitative assessments to quantitative but primarily needs to answer questions regarding 

levels of likelihood and levels of consequence of the event. Good examples for such risk assessments in 

transportation that might translate to this field may be found in States with high seismic activity such as 

California and Washington. 

Integration with other adaptation efforts – An immediate approach for operating agencies is to be part 

of statewide climate change action plans and adaptation efforts. Integration of operations 

considerations such as evacuation procedures, alternate routings, monitoring systems all are worthwhile 

considerations as part of the larger State climate change action plans. 

5. Conclusions

The paper begins to explore the effects of climate change on operations. Effects are going to manifest 

both due to specific weather events/phenomena but also long term trends in air temperature. The link

between weather events and climate is not simplistic, but recent severe weather events point to the 

challenges posed to operations. The scale, frequency, and intensity of events will change how operation 

agencies are organized and function in the country. Similarly, long-term trends will result in behavior 

changes and changes to freight operations that may tax operating agencies in different ways. While 

many questions remain, the role of operations as part of overall climate change adaptation needs to be 

emphasized.
Page 27

6. References

Anisimov, O.A., D.G. Vaughan, T.V. Callaghan, C. Furgal, H. Marchant, T.D. Prowse, H. Vilhjálmsson and 

J.E. Walsh, 2007: Polar regions (Arctic and Antarctic). In: Climate Change 2007: Impacts, Adaptation and 

Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the 

Intergovernmental Panel on Climate Change [M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden 

and C.E. Hanson (eds.)]. Cambridge University Press, Cambridge, UK, 653-685.

Climate Change Science Program (CCSP), 2008: Impacts of Climate Change and Variability on 

Transportation Systems and Infrastructure: Gulf Coast Study, Phase I. A Report by the U.S. Climate 

Change Science Program and the Subcommittee on Global Change Research [Savonis, M. J., V.R. Burkett, 

and J.R. Potter (eds.)]. Department of Transportation, Washington, DC, USA, 445 pp.

Christensen, J.H., B. Hewitson, A. Busuioc, A. Chen, X. Gao, I. Held, R. Jones, R.K. Kolli, W.-T. Kwon, R. 

Laprise, V. Magaña Rueda, L. Mearns, C.G. Menéndez, J. Räisänen, A. Rinke, A. Sarr and P. Whetton, 

2007: Regional Climate Projections. In: Climate Change 2007: The Physical Science Basis. Contribution of 

Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change 

[Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. 

Cambridge University Press, Cambridge, UK.

Federal Highway Administration (FHWA), Office of Operations, 2012: Road Weather Management 

Program. Washington, DC, USA. Accessed 30 Aug 2012 

<http://ops.fhwa.dot.gov/weather/weather_events/snow_ice.htm>.

Federal Highway Administration (FHWA), 2010: Regional Climate Change Effects: Useful Information for 

Transportation Agencies. Office of Planning, Environment and Realty, Office of Infrastructure, Federal 

Highway Administration, U.S. DOT, Washington, DC, 103 pp.

Field, C.B., L.D. Mortsch, M. Brklacich, D.L. Forbes, P. Kovacs, J.A. Patz, S.W. Running and M.J. Scott, 

2007: North America. In: Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of 

Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change 

[M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson (eds.)]. Cambridge 

University Press, Cambridge, UK, 617-652.

Guo, N. H. M. Wilson, and A. Rahbee, 2007: Impact of Weather on Transit Ridership in Chicago, Illinois. 

In: Transportation Research Record, Transportation Research Board of the National Academies. 

Washington, DC, Vol. 2034, 3-10.

Intergovernmental Panel on Climate Change (IPCC), 2000: Special Report on Emissions Scenarios 

(SRES): a Special Report of Working Group III of the Intergovernmental Panel on Climate Change 

[Nakicenovic, N. and R. Swart (eds.)]. Cambridge University Press, Cambridge, UK, 570 pp.

Iowa Department of Transportation (IDOT), 2012: High temperatures causing pavement blowups. Ames, 

IA, USA. Accessed 4 Sep 2012 <http://www.news.iowadot.gov/newsandinfo/2012/07/hightemperatures-causing-pavement-blowups.html>. 

Le Treut, H., R. Somerville, U. Cubasch, Y. Ding, C. Mauritzen, A. Mokssit, T. Peterson and M. Prather, 

2007: Historical Overview of Climate Change. In: Climate Change 2007: The Physical Science Basis. 
Page 28

Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on

Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. 

Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Margreta, M., C. Ford and M.A. Dipo, 2007: U.S. Freight on the Move: Highlights from the 2007 

Commodity Flow Survey Preliminary Data. Research and Innovative Technology Administration (RITA), 

Bureau of Transportation Statistics. Washington, DC, USA. Accessed 30 Aug 2012 

<http://www.bts.gov/publications/

special_reports_and_issue_briefs/special_report/2009_09_30/html/entire.html>. 

Meehl, G.A., T.F. Stocker, W.D. Collins, P. Friedlingstein, A.T. Gaye, J.M. Gregory, A. Kitoh, R. Knutti, J.M. 

Murphy, A. Noda, S.C.B. Raper, I.G. Watterson, A.J. Weaver and Z.-C. Zhao, 2007: Global Climate 

Projections. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the 

Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. 

Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, 

Cambridge, United Kingdom and New York, NY, USA.

National Oceanic and Atmospheric Administration (NOAA), National Climatic Data Center, 2012: Billion 

Dollar Weather/Climate Disasters. Accessed 31 Aug 2012 <http://www.ncdc.noaa.gov/billions>.

Transportation Research Board (TRB), 2011: Adapting Transportation to the Impacts of Climate Change: 

State of the Practice 2011. Transportation Research Circular E-C152. Washington, DC, USA.

Transportation Research Board (TRB), 2008: Potential Impacts of Climate Change on U.S. 

Transportation. Transportation Research Board Special Report 290. National Research Council. 

Washington, DC, USA.

U.S. Department of Transportation (USDOT), 2011: Policy Statement on Climate Change Adaptation. 

Washington, DC, USA. Accessed 4 Sept 2012 

<http://www.fhwa.dot.gov/environment/climate_change/adaptation/policy_and_guidance/usdotpolicy

.pdf>. 

U.S. Department of Transportation (USDOT), 2012: Transportation and Climate Change Clearinghouse. 

Washington, DC, USA. Accessed 4 Sept 2012 <http://climate.dot.gov>. 

U.S. Climate Change Science Program (USCCSP), 2008: Analysis of the Effects of Global Change on 

Human Health and Welfare and Human Systems. Final Report, Synthesis and Assessment Product (SAP) 

4.6. Gamble, J.L. (ed.), K.L. Ebi, A.E. Grambsch, F.G. Sussman, and T.J. Wilbanks (authors). U.S. 

Environmental Protection Agency. Washington, DC, USA.

U.S. Climate Change Science Program (USCCSP), 2008: Preliminary Review of Adaptation Options for 

Climate-Sensitive Ecosystems and Resources. Final Report, Synthesis and Assessment Product (SAP) 4.4. 

Julius, S.H, J.M. West (eds.), J.S. Baron, L.A. Joyce, B. Griffith, P. Kareiva, B.D. Keller, M. Palmer, C. 

Peterson, and J.M. Scott (authors). U.S. Environmental Protection Agency. Washington, DC, USA.

U.S. Climate Change Science Program (USCCSP), 2008: The Effects of Climate Change on Agriculture, 

Land Resources, Water Resources, and the Biodiversity in the United States. Final Report, Synthesis and 
Page 29

Assessment Product (SAP) 4.3. Walsh, M. (ed.), P. Backlund, A. Janetos, and D. Schimel (authors). U.S. 

Environmental Protection Agency. Washington, DC, USA.

U.S. Global Change Research Program (USGCRP), 2009: Global Climate Change Impacts in the United 

States. [Thomas R. Karl, Jerry M. Melillo, and Thomas C. Peterson, (eds.)]. Cambridge University Press, 

New York, NY, USA, 196 pp.

Virginia Department of Transportation (VDOT), 2012: High Temps Put VDOT Crews on Alert for Buckling 

Pavement. Richmond, VA, USA. Accessed 4 Sept 2012 

<http://www.virginiadot.org/newsroom/statewide/2012/high_temps_put_vdot58762.asp>. 
Page 30

Appendix A – Climate Change Impact Tables
Page 31

Table A.1. Transportation-Relevant Climate Change Effects Associated with Climate Trends.

Category Climate Impact Region Date Range Certainty Reference

Air Temperature

Increase in average annual air 

temperature

CONUS 2001-2100 Very likely Christensen et al., 2007

CONUS 2010-2029; 

2040-2059 Very likely ICF International, 2010

Increase in diurnal air 

temperature ranges

Western U.S. 2001-2100 Christensen et al., 2007

Increase in electricity demand for 

air conditioning during summer 

and decrease in electricity 

demand for heating in winter

CONUS 2001-2100 High confidence Field et al., 2007

Increase in average winter

temperatures

CONUS 2010-2029; 

2040-2059 Very likely ICF International, 2010

Precipitation

Increase in average annual 

precipitation

CONUS except south 

and southwestern U.S. 2001-2100 Very likely Christensen et al., 2007

Northeast U.S.

Northwest U.S.

Midwest U.S.

2010-2029; 

2040-2059 Very likely ICF International, 2010

Hawaii 2040-2059 Very likely ICF International, 2010

U.S. Great Plains 2010-2029 Very likely ICF International, 2010

U.S. Great Plains 2040-2059 Likely ICF International, 2010

Decrease in average annual 

precipitation Southwest U.S. 2001-2100 Likely Christensen et al., 2007

Increase in average precipitation 

during winter

Northern U.S. 2001-2100 Christensen et al., 2007

Northeast U.S.

Northwest U.S.

Southwest U.S.

U.S. Great Plains

Midwest U.S. 

2010-2029; 

2040-2059 Very likely ICF International, 2010

Decrease in average precipitation Southern U.S. 2001-2100 Christensen et al., 2007
Page 32

Category Climate Impact Region Date Range Certainty Reference

during summer Northwest U.S.

Southwest U.S.

Southeast U.S.

U.S. Great Plains

Midwest U.S.

Hawaii

2010-2029; 

2040-2059 Very likely ICF International, 2011

Change in seasonal precipitation 

and river flow patterns CONUS 2001-2100 Field et al., 2007

Sea Level and 

Coastal Impacts

Rise in sea level Atlantic and Pacific 

coasts of U.S. 2001-2099 High confidence Meehl et al., 2007

Accelerated coastal erosion Atlantic and Pacific 

coasts of U.S. 2001-2100 Likely Field et al., 2007

Freshwater 

Resources

Increase in precipitation runoff CONUS 2001-2100 Field et al., 2007

Increase in length of erosion 

season and enhancement of 

inland erosion

CONUS 2001-2100 Likely Field et al., 2007

Decrease in water quality CONUS 2001-2100 High confidence Field et al., 2007

Decrease in snow season length 

and snow depth CONUS 2001-2100 Very likely Christensen et al., 2007

Earlier melting and significant 

reductions in snowpack Rocky Mountains 2001-2100 High confidence Field et al., 2007

Lower water levels Great Lakes 2001-2100 High confidence Field et al., 2007

Decreased recharge of heavily 

utilized groundwater-based 

systems

Southwest U.S. 2001-2100 High confidence Field et al., 2007

Local, regional, or state-wide 

shortages of drinking water CONUS 2001-2017 Field et al., 2007

Reduction in winter ice cover Great Lakes 2001-2100 USGCRP, 2009

Shorter ice cover period in 

shallow inland lakes Northern U.S. 2001-2100 Field et al., 2007
Page 33

Category Climate Impact Region Date Range Certainty Reference

Decrease in surface and bottom 

water temperatures of lakes, 

reservoirs, rivers, and estuaries

CONUS 2001-2100 Field et al., 2007

Human Health 

Impacts

Increase in concentrations of 

tropospheric (surface) ozone and 

particulate matter (PM2.5)

CONUS 2001-2050 Field et al., 2007

Increase in respiratory illness CONUS 2001-2100 USCCSP SAP 4.6, 2008

Increase in pollen production CONUS 2001-2100 Likely Field et al., 2007

Increase in heat-related deaths CONUS 2001-2100 USCCSP SAP 4.6, 2008

Increase in extent of Lyme 

disease Northern U.S. 2001-2080 Field et al., 2007

Ecological 

Impacts

Increase in length of growing 

season

CONUS 2001-2100 Medium 

confidence Field et al., 2007

Expanded range of invasive 

species (general) CONUS 2001-2100 USCCSP SAP 4.4, 2008
Page 34

Table A.2. Transportation-Relevant Climate Change Effects Associated with Distinct Climate Events.

Category Climate Impact Region Date Range Certainty Reference

Air 

Temperature 

Events

Increase in intensity, frequency, 

and duration of heat waves

CONUS 2001-2100 High confidence Field et al., 2007

Midwest U.S. by 2100 USGCRP, 2009

Increase in frequency and 

duration of extreme high 

temperature events and 

decrease in extreme low 

temperature events

CONUS 2001-2100 Christensen et al., 2007

Precipitation 

Events

Increase in intensity and 

frequency of extreme 

precipitation events

CONUS 2001-2100 Christensen et al., 2007

Greater variability in 

precipitation events

CONUS 2001-2100 Meehl et al., 2007

Southwest U.S. USGCRP, 2009

Storms and 

Coastal Flooding

Slight poleward shift in storm 

tracks of extra-tropical cyclones

Mid-latitudes 

(30-60 °N) 2001-2100 Christensen et al., 2007

Increase in intensity but 

reduction in frequency of extratropical cyclones

Mid-latitudes 

(30-60 °N) 2001-2100 Christensen et al., 2007; 

Meehl et al., 2007

Increase in peak wind speeds and 

precipitation intensities of 

hurricanes

Atlantic and Eastern 

Pacific coasts of U.S. 2001-2102 Meehl et al., 2007

Increase in frequency and 

severity of coastal flooding 

events

Atlantic and Pacific 

coasts of U.S. 2001-2100 Very high 

confidence Field et al., 2007

Increase in storm surge Atlantic and Pacific 

coasts of U.S. 2001-2101 High confidence Field et al., 2007

Wildfires More frequent wildfires that 

cover larger geographic areas CONUS 2001-2100 Field et al., 2007
Page 35

Table A.3. Transportation-Relevant Climate Change Effects for Alaska.

Category Climate Impact Region Date Range Certainty Reference

Air 

Temperature

Increase in average annual air 

temperature at higher rate than 

CONUS

Alaska 2001-2100 Very likely Christensen et al., 2007

Precipitation

Increase in average annual 

precipitation

Alaska 2001-2100 Very likely Christensen et al., 2007

Alaska 2010-2029; 

2040-2059 Very likely ICF International, 2010

Increase in frequency of very 

warm and wet winters and 

summers

Alaska 2001-2100 Christensen et al., 2007

Increase in average precipitation 

during winter Alaska 2010-2029; 2040-2059 Very likely ICF International, 2010

Ice, Snow, and 

Permafrost

Thinning and reduction in extent 

and thickness of annually 

averaged Arctic sea ice

Alaska 2001-2100 Very likely Christensen et al., 2007

Warming, thawing, and decrease 

in areal extent of terrain 

underlain by permafrost

Alaska (Arctic) 2001-2100 Anisimov et al., 2007

Reduction in seasonal snow cover 

on land Alaska (Arctic) 2001-2101 Anisimov et al., 2008

Storms Reduction in medium-strength 

extra-tropical cyclones Poleward of 70 °N 2001-2100 Christensen et al., 2007
Page 36

Table A.4. Likelihood Terminology for Climate Change Effects. [Adapted from Le Treut et al., 2007]

IPCC Likelihood Terminology Likelihood of the Impact

Virtually certain > 99% probability

Extremely likely > 95% probability

Very likely > 90% probability

Likely > 66% probability

More likely than not > 50% probability

About as likely as not 33 to 66% probability

Unlikely < 33% probability

Very unlikely < 10% probability

Extremely unlikely < 5% probability

Exceptionally unlikely < 1% probability

Table A.5. Confidence Terminology for Climate Change Effects. [Adapted from Le Treut et al., 2007]

IPCC Confidence Terminology Degree of Confidence in Being Correct

Very high confidence At least 9 out of 10 chance

High confidence About 8 out of 10 chance

Medium confidence About 5 out of 10 chance

Low confidence About 2 out of 10 chance

Very low confidence Less than 1 out of 10 chance
Page 37
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