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Sensitivity Matrix

Sensitivity Screen

Italics = Sensitive: Changes in the climate stressor impact the asset to some degree.

Non-Italics = Not sensitive: A very large change in the climate stressor (within reason) would not impact the asset.

Asset Categories   Sea Level Rise and Storms Precipitation Temperature
Mode Sub-Mode Relative Sea Level Rise (Gradual) Storm Surge (inc. wave action and SLR impacts) Wind Incremental change in the mean (+/-) Increase in frequency or duration of heavy rain events Drought Incremental increase in the mean Increase in frequency or duration of heat events
Bridges Bridge (Superstructure)   Damage increases substantially when storm surge height equals low chord bridge elevation. At this point, the bridge is usually exposed to direct wave impacts on the superstructure. Recent guidance specifies that the vertical clearance of highway bridges should provide at least 1 foot of clearance over the 100-year design wave crest elevation. Design standards require bridges in Mobile to withstand a 130-150 mph wind. Bridge likely closed to traffic at 56 mph.   Scour can make bridge more susceptible to collisions, wave action, and other impacts.     Bridge pavement is usually concrete and may exhibit similar sensitivities as road concrete pavement.
Bridge (Substructure, Abutment and Approach) Sea level rise increases the base elevation of water during storm surge, thereby increasing damage due to scour, wave action, uplift and other stressors. Design standards require that bridge foundations withstand scour resulting from a 100 year storm. Strong winds create more powerful waves which can stress the bridge superstructure and substructure.   Scour at bridge foundations should designed to withstand the 100-year flood storm surge.      
Operator Houses (movable bridges) and electrical parts   If exposed, electrical components are very sensitive to low levels of salt water flooding. Movable bridges may begin to close operations at wind speeds of around 40 mph. Physical damage to operator houses has occurred historically at wind levels of 125 mph. Damage from wind tends to be minor.   Damage would require wind or storm damage to expose operator house and electrical equipment.      
Roads and Highways Paved roads (surface and subsurface) Sea level rise increases the risk of erosion and flooding damage to coastal roads. Threshold depends on elevation of road, coastal protection, and other factors. Direct damage to road begins occurring once storm surge overtops road, particularly if waves are in direct contact with road structure. There is some protection from wave action if road is deeply overtopped or covered with sand.     While lower functional class roadways are typically designed for the 10-25 year storm, Mobile County roads are generally designed for larger storms. No documented relationship, but some sensitivity is likely.   In Mobile, pavement may exhibit sensitivity at sustained air temperatures of 108 degrees F, particularly on routes with a high level of truck traffic.
Unpaved roads Most coastal roads do not have unpaved surfaces. However, if exposed, unpaved roads are more sensitive to erosion and damage caused by sea level rise than paved roads. Most coastal roads do not have unpaved surfaces. However, if exposed, unpaved roads are more sensitive to storm surge damage than paved roads. Moderate winds stir up dust from unpaved roads, resulting in minor discomfort and damage. No documented relationship, but some sensitivity is likely. No documented impacts, but high sensitivity to washout from flooding likely. No documented relationship, but some sensitivity is likely.    
Stormwater drainage (culverts, side drains, etc) Sea level rise increases potential for flooding of the stormwater drainage system. Storm surge can flood the stormwater drainage system beyond its design capacity. Damage from wind creates debris, which can exacerbate flooding damages to storm surge. Culverts: 25 year storm capacity (Mobile County design standards)
Cross drains: 10 year storm capacity (Mobile County design standards)
Side drains: 10-25 year storm capacity (Mobile County design standards)
In Mobile, destructive flooding generally does not occur until around 50 to 100 year storm.
Culverts, cross drains, and side drains are designed to 25-, 10-, and 10 to 25-year storm capacity, respectively.
No documented relationship, but some sensitivity is likely.    
Highway, road and street signs and traffic lights   Flooding can damage electrical components, causing traffic lights and other signals to malfunction. Alabama AASHTO wind design speed is 140 mph; if signs are not buried deep enough, failure can occur at lower wind speeds (e.g., sign failures at 90 mph have been recorded in Miami-Dade county).   Heavy rainfall can impact visibility of signs.      
Road Work and Maintenance, Driver Safety, and Traffic and Service   If exposed to storm surge, road usually closed or rendered inoperable. Danger to road maintenance workers and road users at windspeeds of 40 mph; conditions become very dangerous at windspeeds of 75 mph. Very light rain reduces road capacity by 1 to 3% and roadway speed by 1 to 2%.
Light rain can reduce road capacity by 5 to 10% and roadway speed by 2 to 4%.
Heavy rain reduces roadway speed by 4 to 7%.
  No documented relationship, but some sensitivity is likely. Health and safety risk as well as possible engine/equipment heat stress begins at around 85F, but the situation becomes more critical at 105-110F. Restrictions limiting the number of hours that road crew maintenance can work begin at 85F. At 110F, operations are generally restricted.
Railroads Electrical Equipment (gates/flashers and signal bungalows) Equipment may become inundated. Exposure to storm surge can cause failure of electrical components, such as signals. Winds (head, cross, or tail) >= 50 mph   If exposed, inundation of equipment can lead to electrical damages due to inundation of equipment.   Risk to electric rail components increases at temperatures equal to or exceeding 90 °F.
Railroad Tracks, Ties, and Ballast Equipment may become inundated. Wave action can strip rail, ties, and ballast off of railroad bridges if they are exposed.     Immersion of wooden ties in water softens/expands the wood, weakening its ability to support tracks. Erosion of supporting systems (such as ballast and other nearby ground) can threaten track stability.   For steel railroad tracks: at 90 degrees F, rail speed is slowed to prevent buckling; buckling risks become pronounced above a threshold temperature of 110 degrees F.
Railroad services (i.e., operations) Equipment may become inundated. Storm surge can scour the railbed, derail rail cars, and damage railway bridges over streams, all of which can disrupt service. Wind speeds greater than 50 mph can cause damage to electrical lines. Three-second gust basic wind speed used to determine the pressures that buildings and other structures must withstand according to ASCE 7-05 is 130 to 150 mph in the Mobile area.   Heavy precipitation or any flooding can cause damage. Just a couple of inches of flooding can short out locomotive motors.   Health and safety risks for workers at a heat index greater than 105 degrees F can lead to operational delays.
Airports/ Heliports Runway and navigational aids Sea level rise exacerbates storm surge elevation. Runways are sensitive to low levels of flooding, the storm surge threshold is therefore essentially equal to the airport elevation.     Heavy rain of 1 to 2 inches per hour can lead to standing water on runway, causing delays.   Low sensitivity - For range of expected temperature increases in Mobile area, effects on runway length requirements are negligible.  
Aircraft     Cross-wind landing and take-off speed limit for most small aircraft is 23 mph; limit for larger aircraft can range from 46 mph in dry conditions to 20 mph on iced runways.   Wet runways can lower aircraft cross-wind takeoff/landing limits.
Hail greater than 1 inch in diameter can severely damage aircraft.
     
Airfield buildings and structures (e.g., terminal buildings, hangers, air traffic control tower)   Airport buildings are sensitive to low levels of flooding, the storm surge threshold is therefore essentially equal to the airport elevation. Basic wind speed used to determine the pressures that buildings and other structures must withstand according to ASCE 7-05 is 130 to 150 mph in the Mobile area. Certain airport buildings are considered "essential facilities" and are designed to withstand greater pressures.       Increased temperatures will increase cooling requirements in terminals and buildings  
Services and airport/ heliport operations (e.g., flight departures and arrivals, baggage/cargo transfers, ground transportation)   Airport services are sensitive to low levels of flooding, the storm surge threshold is therefore essentially equal to the airport elevation. Airports close in hurricane conditions (i.e., windspeeds greater than 74 mph)   Thunderstorms with lightning within 3, 5, or 17 nautical miles and heavy rain of 1 to 2 inches per hour can cause delays.     Higher temperatures may limit the types of aircraft that can take off on certain days, or pilots may have to adjust cargo or passengers to lower weight.
Natural Oil and Gas Pipelines Pipelines, aboveground   Sensitivity generally low Wind speeds above 60 mph can damage pipeline systems.   Damage caused by weakened soil structure due to precipitation or inundation from storms. Pipeline roadbed can be scoured by heavy precipitation.      
Pipelines, underground   Sensitivity generally low     Damage caused by weakened soil structure due to precipitation or inundation from storms.
Pipeline may be unearthed from flooding.
     
Pipelines, offshore   Offshore oil and gas infrastructure is designed to withstand the 100 year storm. Historically in the Gulf Coast, damage to pipelines has drastically increased at around a Category 4 hurricane (Cat 4 storms are characterized by 130-155 mph winds and 13-18 foot storm surges).          
Aboveground infrastructure (e.g., compressor stations, metering stations, other buildings, structures)   No documented relationship, but some sensitivity is likely. Wind can damage buildings at speeds greater than 30 to 40 mph; basic wind speed used to determine the pressures that buildings and other structures must withstand according to ASCE 7-05 is 130 to 150 mph in the Mobile area.          
Electric Power Systems Electric Power Systems   Wind, storm surge, and waves damage essentially every component of electric power systems (transmission lines, towers, insulators, generating plants) through direct flooding impacts, damage from debris, and other effects such as salt spray contamination. Risk of damage from wind increases around threshold of 45 mph.   Low sensitivity; soil moisture effects electrical power system components, such as poles. Drier conditions can increase the likelihood that trees will snap and break in storms, damaging power lines.   Increased demand for air conditioning can stress electric power systems during heat events.
Marine Ports, Terminals, and Waterways Electrical Equipment   If exposed, high sensitivity. No documented relationship, but some sensitivity is likely.   If exposed, some sensitivity.      
  Terminal Buildings   Damage is likely to occur when wave height overtops elevation of port. Design wind speed for Mobile port structures ranges from 130-140 mph (3-second gust).          
Channels No documented relationship, but some sensitivity is likely. Storm surge can wash debris and sediment into the shipping channels, necessitating dredging following the storm.       Lower water levels due to drought decrease the cargo limits for shipping, especially for barges.    
Piers, wharves, and berths   Damage is likely to occur when wave height overtops elevation of port. Indirect impacts due to increased wave height.         Paved piers could be susceptible to surface buckling
Port services (i.e., operations) No documented relationship, but some sensitivity is likely. Storms cause damage to marine port services by disrupting the power and communications networks, displacing port workers, washing away channel buoys, and submerging debris in ship channels. Berthing large vessels is affected when windspeeds exceed 23 mph; high-speed ferries stop operating at windspeeds of roughly 46 mph; container and gantry-type cranes at affected by sustained windspeeds greater than 29 mph.   No documented relationship, but some sensitivity is likely. No documented relationship, but some sensitivity is likely.   No documented relationship, but some sensitivity is likely.
Updated: 03/27/2014
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