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Conditions, Performance & Safety

Pavement Surface Condition of the NHS and Interstate System

Pie charts illustrating NHS and Interstate system surface condition

Pavement condition overall has improved on the Interstate system and the NHS over the past several years. In 2000, 96.6% of the Interstate system and 93.5% of the NHS was at acceptable ride quality as measured by the International Roughness Index (IRI). IRI is an objective instrument based rating system that has been used an an indicator of pavement performance as measured by rideability. Pavements with IRI <170 can be considered to have an acceptable ride quality, while those with an IRI <95 can be considered to have a good or very good ride quality.


Bridge Conditions

Table showing Bridge Conditions by NHS, Other Federal-Aid, and Non Federal-Aid Highways

Note: FA = Federal-aid

1/ Includes all Interstate and other principal arterials.

2/ Includes all other highways except minor collectors and local roads and streets.

3/ Includes rural minor collectors and local roads and streets.

Source: Federal Highway Administration, Office of Engineering, National Bridge Inventory Data.

Twenty nine percent of the Nation's estimated 585,542 bridges are structurally deficient or functionally obsolete. Twenty-three percent of the 130,224 bridges on the NHS (Interstate and all other principal arterials) are structurally deficient or functionally obsolete.

A structurally deficient bridge is closed or restricted to light vehicles only because of deteriorated structural components. Structurally deficient bridges are not necessarily unsafe. Strict observance of signs limiting traffic or speed on bridges will generally provide adequate safeguards for those using the bridges.

A functionally obsolete bridge is one that cannot safely service the volume or type of traffic using it. These bridges are not unsafe for all vehicles, but have older design features that prevent them from accommodating current traffic volumes and modern vehicle sizes and weights.


Travel Congestion on Urban Principal Arterial Roads

Bar Chart showing Peak Period Vehicle Miles of Travel Occuring Under Congested Conditions (%) for 1995 at 40%, 1996 at 40%, 1997 at 40%, 1998 at 41%, 1999 at 37%, and 2000 at 38%

Peak period travel congestion on urban principal arterial roads have remained fairly stable over the past 6 years. The measure of congestion used in this analysis is the Volume/Service Flow (V/SF) Ratio. As this ratio get larger, traffic slows and eventually stops as the theoretical value of 1.00 is approached (the volume of traffic equals service flow capability of the facility). V/SF ratio of greater than or equal to 0.80 is used here to indicate congestion.


Motor-Vehicle Fatalities and Travel

Graph showing motor-vehicle fatalities and travel by year

Source: National Highway Traffic Safety Administration, Fatality Analysis Reporting System.

Fatalities decreased from 1978 to a low of 39,230 in 1992 However, they have since risen to 42,387 in 2000. Of the fatalities in 2000, 13.5% occurred on the Interstate System.


Fatality Rates

Line graph illustrating fatality rates for Interstate and all systems from 1980 to 2000

Source: National Highway Traffic Safety Administration, Fatality Analysis Reporting System.

The fatality rate (fatalities per 100 million vehicle-miles of travel) on all highway system continues to decline. In 2000, the fatality rate reached 1.53 , a 54% decrease from 1980. The decrease in the fatality rate occurred despite a 81% increase in highway travel and a 40% increase in motor vehicle registrations during the 1980 to 2000 time period. The fatality rate (0.85) on the Interstate System is a little more than one-half the rate on all highway systems.


Principal Classes of Motor-Vehicle Deaths

Flow chart showing fatalities broken out by Urban and Rural, day or night, and number of vehicle occupants versus non-vehicle occupants

Source: National Highway Traffic Safety Administration, Fatality Analysis Reporting System (FARS).

In 2000, 59% of motor-vehicle death occurred in places classified as rural. In urban areas, nearly 24% of the victims were non-occupants; in rural areas, the victims were mostly occupants of motor vehicles. Almost half of all deaths occurred at night.


Fatalities Involving Medium / Heavy Trucks 1/

Pie charts showing fatalities involving medium and heavy trucks for 1998 and 2000 by truck occupants, occupants in other vehicles, and non-occupants

1/ Medium Heavy Truck-Single unit truck with gross vehicle weight greater than 10,000 lbs., tractor-trailer combination, truck with cargo trailer(s), or truck-tractor pulling no trailer.

Source: National Highway Traffic Safety Administration, Fatality Analysis Reporting System.

There were 5,307 fatalities in crashes involving medium and heavy trucks in 2000, down from 5,374 in 1998. Occupants in other vehicles accounted for 78% of the fatalities involving medium and heavy trucks. There were 67 less fatalities in crashes involving medium and heavy truck from 1998 to 2000. Occupants in other vehicles shows a decrease of 71 fatalities involving medium and heavy trucks while the non-occupant fatalities also decreased by 15 over the same two years.

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United States Department of Transportation - Federal Highway Administration