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Climate Change & Extreme Weather Vulnerability Assessment Framework

Appendix B: Climate Effects and Impacts

Table B1: Impacts of temperature on highway operations and infrastructure.

Source: FHWA (2010)

Climate Effects

Impacts on Infrastructure and Operations

Title: Extreme Rutting - Description: Photo of rutting along the shoulder of a road.

Extreme Rutting. Source:

Increases in very hot days and heat waves (higher high temperatures, increased duration of heat waves)

  • Increased thermal expansion of bridge joints and paved surfaces, causing possible degradation.
  • Concerns regarding pavement integrity, traffic related rutting and migration of liquid asphalt, greater need for maintenance of roads and pavement.
  • Limits on periods of construction activity, and more night time work.
  • Vehicle overheating and tire degradation.
  • Maintenance and construction costs for roads and bridges are likely to increase as temperatures increase.
  • Stress on bridge integrity due to temperature expansion of concrete joints, steel, asphalt, protective cladding, coats and sealants.
  • Asphalt degradation, resulting in possible short term loss of public access or increased congestion of sections of road and highway during repair and replacement .

Decreases in very cold days

  • Regional changes in snow and ice removal costs and environmental impacts from salt and chemical use.
  • Fewer cold-related restrictions for maintenance workers.

Later onset of seasonal freeze and earlier onset of seasonal thaw

  • Changes in seasonal weight restrictions.
  • Changes in seasonal fuel requirements.
  • Improved mobility and safety associated with a reduction in winter weather.
  • Longer construction season in colder areas.
  • Freeze-thaw conditions increasing frost heaves and potholes restricting loads on roads.

Table B2: Impacts of precipitation on highway operations and infrastructure.

Source: FHWA(2010)

Climate Effects

Impacts on Infrastructure and Operations

Collapse of 287 North: Before and After

NJ 287 collapse from Hurricane Irene.

Source: NJ DOT

Increases in intense

precipitation events

  • Increases in weather-related delays and traffic disruptions.
  • Increased flooding of evacuation routes.
  • Increases in flooding of roadways and tunnels.
  • Increases in road washout, landslides and mudslides that damage roadways.
  • Drainage systems likely to be overloaded more frequently and severely, causing backups and street flooding.
  • Areas where flooding is already common will face more frequent and severe problems.
  • If soil moisture levels become too high, structural integrity of roads, bridges, and tunnels (especially where they are already under stress) could be compromised.
  • Standing water will have adverse effects on road base.
  • Increased peak streamflow could affect the sizing requirement for bridges and culverts.

Photo of a trestle bridge on fire

Trestle fire in eastern Washington

Source: Image from Washington State Department of Transportation, Climate Impacts Vulnerability Assessment, November 2011.

Increases in

drought conditions

  • Increased susceptibility to wildfires, causing road closures due to fire threat or reduced visibility.
  • Increased risk of mudslides in areas deforested by wildfires.

Photo of washed out SR 12.

Slope Failure. SR 12. Source WSDOT

Changes in seasonal precipitation

and river flow patterns

  • Benefits for safety and reduced interruptions if frozen precipitation shifts to rainfall.
  • Increased risk of floods, landslides, slow failures and damage to roads if precipitation changes from snow to rain in winter and spring thaws.
  • Increased variation in wet/dry spells and decrease in available moisture may cause road foundations to degrade.
  • Degradation, failure and replacement of road structures due to increases in ground and foundation movement, shrinkage and changes in groundwater.
  • Increased maintenance and replacement costs of road infrastructure.
  • Short term loss of public access or increased congestion to sections of road and highway.

Table B3: Impacts of storm intensity on highway operations and infrastructure.

Source: FHWA(2010)

Climate Effects

Impacts on Infrastructure and Operations

photo of highway 90 bridge with collapsed bridge deck sections.

Hurricane Damage from Wave Action to

Highway 90 in Bay St Louis, MS


Increases in storm intensity

(leading to higher storm surges,

stronger winds, flooding)

  • More frequent and potentially more extensive emergency evacuations.
  • More debris on roads, interrupting travel and shipping.
  • Bridges, signs, overhead cables and other tall structures are at risk from increased wind speeds.
  • Increased threat to stability of bridge decks.
  • Decreased expected life-time of highways exposed to storm surge.
  • Risk of immediate flooding, damage caused by force of water and secondary damage caused by collisions with debris.
  • Erosion of coastal highways and land supporting coastal infrastructure.
  • Damage to signs, lighting fixtures, and supports
  • Reduced drainage rate of low-lying land after rainfall and flooding events.

Table B4: Impacts of sea level rise on operations and highway infrastructure.

Source: FHWA(2010)

Climate Effects

Impacts on Infrastructure and Operations

Three breaches in NC12 after Irene by Tom MacKenzie FWS.jpg

Three breaches in NC12 after Hurricane Irene Photo Credit: Tom MacKenzie, US FWS

Rising sea levels (leading to higher storm surge, increased salinity of rivers and estuaries, flooding)

  • Amplifies effect of storm surge, causing more frequent interruptions to coastal and low-lying roadway travel due to storm surges.
  • Amplifies effect of storm surge, causing more severe storm surges requiring evacuation.
  • Permanent inundation of roads or low lying feeder roads in coastal areas. Reduces route options/redundancy.
  • More frequent or severe flooding of underground tunnels and low-lying infrastructure.
  • As the sea level rises, the coastline will change and highways that were not previously at risk to storm surge and wave damage may be exposed in the future.
  • Erosion of road base and bridge supports.
  • Highway embankments at risk of subsidence/heave.
  • Bridge scour.
  • Reduced clearance under bridges.
  • Increased maintenance and replacement costs of tunnel infrastructure.
Updated: 10/20/2015
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