TRIP REPORT: AT 65 YEARS OLD, U.S. INTERSTATE SYSTEM IS HEAVILY TRAVELED, CONGESTED AND DETERIORATING

…CONGRESSIONALLY REQUESTED REPORT FINDS THAT MOST OF INTERSTATE SYSTEM NEEDS TO BE RECONSTRUCTED AND MODERNIZED, REQUIRING MORE THAN A DOUBLING OF CURRENT FUNDING

As the U.S. Interstate Highway System reaches 65 years old, it is congested, carries significant levels of travel – particularly by large trucks – and lacks adequate funding to make needed repairs and improvements. America’s most critical transportation link will need to be rebuilt and expanded to meet the nation’s growing transportation needs, according to a report released today by TRIP, a national transportation research nonprofit. The report, America’s Interstate Highway System at 65: Meeting America’s Transportation Needs with a Reliable, Safe & Well-Maintained National Highway Network, looks at the Interstate system’s use, condition and benefits, and the findings of a 2019 report prepared by the Transportation Research Board (TRB)  at the request of Congress as part of the Fixing America’s Surface Transportation (FAST) Act, on the condition and use of the Interstate system and actions required to restore and upgrade the Interstate system.

The chart below ranks states whose Interstate systems are the most congested, have experienced the greatest increase in vehicle miles of travel (VMT) since 2000, are busiest (based on daily travel per lane mile), have the largest share of pavement in poor condition, and have the greatest share of bridges in poor/structurally deficient condition. Data for all states can be found in the Appendix

According to the 2019 TRB report, the Interstate system has a persistent and growing backlog of physical and operational deficiencies as a result of age, heavy use and deferred reinvestment, and is in need of major reconstruction and modernization. The TRB report concludes that annual investment in the Interstate Highway System should be increased approximately two-and-a-half times, from $23 billion in 2018 to $57 billion annually over the next 20 years.

“The report released by TRIP confirms what American businesses experience every day—our Interstate Highway System, which was once the envy of the world, is in serious need of modernization,” said Ed Mortimer, vice president of transportation infrastructure, U.S. Chamber of Commerce. “Commitment to modernization must be shared by federal, state and local leaders as well as the private sector. The Interstate system plays a key national role in economic success and quality of life for every American, and we urge bipartisan solutions this year to address this critical issue.”

The TRIP report found that from 2000 to 2019, travel on the Interstate system, the importance of which was heightened during the COVID-19 pandemic, has increased by 26 percent — a rate nearly triple that at which new lane capacity was added. As a result, 47 percent of urban Interstate highways are considered congested during peak hours.   Due to the COVID-19 pandemic, vehicle travel on U.S. highways dropped by as much as 45 percent in April 2020 (compared to April 2019) but rebounded to six percent below April 2019 levels by April 2021.

The report also found that travel by combination trucks on the Interstate increased at a rate more than double that of overall vehicle travel between 2000 and 2019. Combination truck travel on the Interstate system increased 43 percent from 2000 to 2019, while overall vehicle travel increased 19 percent. 

“Our rapidly deteriorating infrastructure is a clear and present danger to our nation’s supply chain. Breakdowns in the Interstate Highway System add an annual $75 billion to the cost of freight transportation, and 67 million tons of excess carbon dioxide emissions are released into the atmosphere every year from trucks stuck in traffic congestion,” said Chris Spear, president and CEO of the American Trucking Associations. “This report quantifies how severe this crisis has become, and it underscores the urgent need for Congress to make real infrastructure investments that are backed by a fair and equitable user-based revenue source.”

The design of the Interstate – which includes a separation from other roads and rail lines, a minimum of four lanes, paved shoulders and median barriers – makes it more than twice as safe to travel on as all other roadways. The fatality rate per 100 million vehicle miles of travel on the Interstate in 2019 was 0.55, compared to 1.30 on non-Interstate routes. TRIP estimates that additional safety features on the Interstate Highway System saved 6,555 lives in 2019. 

“AAA supports increased federal investment for the Interstate Highway System. Significant funding is needed to ensure safe, efficient and reliable mobility across the United States,” said Jill Ingrassia, AAA executive director of advocacy and communications. “AAA urges Congress and the administration to come together to get this important work done.”

TRIP’s report finds that while pavement smoothness on most segments of the Interstate system is acceptable, the crumbling foundations of most highway segments need to be reconstructed, and that continued resurfacing — rather than addressing underlying foundational issues — is resulting in diminishing returns and results in shorter periods of pavement smoothness.  

As the aging system’s foundations continue to deteriorate, most Interstate highways, bridges and interchanges will need to be rebuilt or replaced, the TRB report finds. According to the TRIP report, pavements on 11 percent of Interstate highways are in poor or mediocre condition.  Three percent of Interstate bridges are rated in poor/structurally deficient condition and 57 percent are rated in fair condition.

Restoring and upgrading the Interstate Highway System to meet the nation’s 21st Century transportation needs will require a significant boost in funding, strong federal leadership and a robust federal-state partnership to reestablish the Interstate Highway System as the nation’s premier transportation network.  The current federal surface transportation program, Fixing America’s Surface Transportation (FAST Act), the primary source of Interstate highway funding, expired on September 30, 2020 and was extended by one year by Congress to September 30, 2021. Reauthorization of a new long-term, adequately and reliably funded long-term federal program will be needed to ensure that a strong federal program supports the restoration of the Interstate system.  

Based on the findings of the TRB Interstate report, TRIP has provided a set of recommendations for the restoration of the Interstate Highway System, which includes:  the foundational reconstruction of Interstate highways, bridges and interchanges; improvement to roadway safety features; system right-sizing, including upgrading of some roadway corridors to Interstate standards; adding needed additional highway capacity on existing routes; adding additional corridors; and, modifying some urban segments to maintain connectivity while remediating economic and social disruption. 

“The long-term vision that helped establish the current Interstate Highway System 65 years ago is needed again today,” said Dave Kearby, TRIP’s executive director. “A modernized Interstate system will be critical to the nation’s ability to fully recover from the COVID-19 pandemic and will require adequate investment in a federal surface transportation program that provides states and local government the funding and flexibility they will need to restore the nation’s most critical transportation link.”

AMERICA”S INTERSTATE HIGHWAY SYSTEM AT 65

Executive Summary

At sixty-five years old, an age at which many Americans are considering retirement and reduced workloads, the Interstate Highway System is deteriorating, its traffic load of cars and trucks continues to increase, and the system lacks an adequate plan for its long-term health. 

The Interstate Highway System remains the workhorse of the U.S. transportation system: heavily traveled and providing the most important link in the nation’s supply chain, and the primary connection between and within urban communities. The importance of the Interstate Highway System and the reliable movement of goods it provides was heightened during the response to the COVID-19 pandemic and the ongoing recovery. But, America’s Interstate highways are wearing out and showing signs of their advanced age, often heavily congested, and in need of significant reconstruction, modernization and expansion.

In 2015, as part of the Fixing America’s Surface Transportation (FAST) Act, the U.S. Congress asked the Transportation Research Board (TRB), a division of the National Academy of Sciences, Engineering and Medicine, to conduct a study to determine actions needed to upgrade and restore the Interstate Highway System to fulfill its role of safely and efficiently meeting the nation’s future critical personal, commercial and military travel needs. In 2019, the TRB provided Congress with a report that found that the nation’s Interstates are heavily congested and aging, with large portions of the system in need of major reconstruction and modernization. The report found that addressing the needs of the Interstate Highway System will require more than a doubling of current investment to adequately improve the system’s condition, reliability and safety, and that the restoration of the nation’s Interstate Highway System should be based on strong federal leadership of a collaborative effort with the states. 

TRIP’s America’s Interstate Highway System at 65 report provides the latest information on the Interstate system, including pavement conditions, bridge conditions, travel trends, traffic congestion levels, truck use, and traffic safety. It reviews the findings of the TRB Interstate report and concludes with recommended actions – based on the findings of the TRB report – to ensure that the system is able to meet the nation’s transportation needs. 

TRB Interstate HIGHWAY SYSTEM REPORT REQUESTED BY CONGRESS

In 2015, as part of the Fixing America’s Surface Transportation (FAST) Act, the U.S. Congress requested a report evaluating the condition of the Interstate Highway System and providing recommendations on actions required to restore and upgrade the System to meet the growing and shifting transportation demands of the 21st Century. The report was conducted by the Transportation Research Board (TRB), a division of the National Academies of Sciences, Engineering and Medicine. The findings of the TRB report, released in 2019, include:

  • The Interstate Highway System has a persistent and growing backlog of physical and operational deficiencies as a result of age, heavy use and deferred reinvestment, and is in need of major reconstruction and modernization.
  • Most roadway segments of the Interstate Highway System retain their original underlying foundations and need to be completely rebuilt from the subbase up.
  • The repeated resurfacing of Interstate highways is not addressing the deterioration of roadway subbases. Repeated resurfacing – rather than addressing underlying foundational issues – provides diminishing returns as additional resurfacing results in increasingly shorter periods of pavement smoothness and is likely to result in higher lifecycle costs than periodic reconstruction.
  • The modernization of the Interstate Highway System needs to include the following:  reconstruction of the majority of Interstate highways and bridges, including their foundations; the upgrade of most interchanges to improve their function and safety; the addition of capacity along existing corridors, the construction of new routes and the conversion of some existing routes to Interstate standards; the modification of some urban segments to maintain connectivity while remediating economic and social disruption; and, further improvement of highway safety features.  
  • To address the physical and operational deficiencies identified in the TRB report, annual investment in the Interstate Highway System should be increased by approximately two-and-a-half times, from its current level of $23 billion in 2018 to $57 billion annually over the next 20 years.
  • The restoration of the nation’s Interstate Highway System will require strong federal leadership and a robust federal-state partnership.

Interstate Use and Characteristics

The Dwight D. Eisenhower National System of Interstate and Defense Highways, which has been called the most ambitious public works project built since the Roman Empire, is the most critical link in the nation’s transportation system.

  • The Interstate Highway System, which includes 2.6 percent of all roadway lane miles in the U.S., carries 26 percent of the nation’s vehicle travel.
  • The 48,482-mile Interstate Highway System includes 10 transcontinental routes and highways varying in length from 18 miles to more than 3,000 miles.
  • Since funding of the Interstate system was approved in 1956 to 2019, annual vehicle miles of travel (VMT) in the U.S. increased by 427 percent, from 626 billion miles driven, to approximately 3.3 trillion miles driven.
  • From 1956 to 2019, the number of vehicles in the nation increased by 324 percent, from 65 million vehicles to 276 million vehicles. The nation’s population increased by 96 percent, from 168 million to 329 million during this time. 
  • Due to the COVID-19 pandemic, vehicle travel on the U.S. Interstate Highway System dropped by as much as 45 percent in April 2020 (as compared to vehicle travel during the same month the previous year) but rebounded to six percent below April 2019 (the previous pre-COVID-19 April) levels by April 2021.

INTERSTATE HISTORY

The need for a transcontinental highway system in the U.S. was recognized as early as 1919, and an initial Interstate plan was completed in the late 1930s. But it was not until Congress approved a suitable funding mechanism in 1956 that the Interstate Highway System became a reality.

  • In 1919, Lieutenant Dwight D. Eisenhower participated in the U.S. Army’s first transcontinental motor convoy, from Washington, DC, to San Francisco, California.  The trip took 62 days, largely due to inadequate roads and highways.
  • In 1954, President Eisenhower appointed a committee to draft a proposal to fund a national system of Interstate Highways.  The initial proposal, subsequently dismissed by Congress, called for financing a national Interstate system through bond financing.
  • Nationwide construction of the Interstate Highway System began in 1956 following the approval of the Federal-Aid Highway Act of 1956.  Some segments of urban and regional highways built prior to 1956 were later incorporated into the Interstate Highway System.
  • The Federal-Aid Highway Act of 1956, signed into law by President Dwight Eisenhower on June 29, 1956, called for the construction of a 41,000-mile system of Interstate highways.  The Act called for the Interstates to be paid for by taxes on motorists, such as the federal motor fuel tax, with the federal government paying 90 percent of the initial construction costs.  
  • The federal motor fuel tax was set at three cents-per-gallon in 1956. Last increased in 1993, the tax is currently 18.4 cents-per-gallon.
  • Revenue collected from the 18.4 cents-per-gallon federal motor fuel tax and the 24.4 cents-per-gallon federal diesel fuel tax are the primary sources of funding for the federal Highway Trust Fund, which distributes funds to state and local governments for highway and bridge repairs as well as other surface transportation improvements, including public transit, pedestrian and bicycling facilities.

INTERSTATE ROAD AND BRIDGE CONDITIONS

While pavement smoothness and bridge conditions on the Interstate system are acceptable, as the aging system’s foundations continue to deteriorate, most Interstate highways, bridges and interchanges will need to be reconstructed or replaced.   

  • Pavements on 11 percent of Interstate highways are in poor or mediocre condition, with three percent rated in poor condition and eight percent rated in mediocre condition.  Another nine percent of Interstate pavements are in fair condition and the remaining 80 percent are in good condition.
  • The chart below shows the states with the greatest share of their Interstate highways with pavements in poor condition.  Data for all states can be found in the Appendix
  • Three percent of the nation’s Interstate bridges are rated in poor/structurally deficient condition, and 57 percent are rated in fair condition.  A bridge is rated in poor/structurally deficient condition if there is significant deterioration of the bridge deck, supports or other major components.  
  • The chart below shows states with the greatest share of Interstate bridges rated poor/structurally deficient.  Data for all states can be found in the Appendix
  • The intended lifespan of many of the nation’s Interstate bridges at the time of their construction is 50 years, though newer bridges are often built with longer-lasting materials and techniques that allow for a longer intended lifespan. Older bridges often need significant repairs or rehabilitation or may need to be replaced to continue to provide adequate service.   
  • The average age of the nation’s Interstate bridges is 46 years. Fifty-four percent of the nation’s Interstate bridges are at least 50 years old. The chart below shows states with the largest share of Interstate bridges 50 years old or older. Data for all states can be found in the Appendix

INTERSTATE CONGESTION

Traffic congestion is increasing on the Interstate Highway System as the amount of vehicle travel far outstrips the capacity added to the system. Nearly half of the length of the nation’s urban Interstates is congested.  

  • Travel on the nation’s Interstate highways is increasing at a rate nearly triple the rate that new lane capacity is being added. From 2000 to 2019, vehicle travel on Interstate highways increased 26 percent, from 662 billion miles traveled annually to 837 billion miles. From 2000 to 2019, lane miles of Interstates increased nine percent, from 208,502 to 227,129. miles. 
  • Forty-seven percent of the nation’s urban Interstate highways (9,046 of 19,177 miles) are considered congested because they carry traffic levels that result in significant delays during peak travel hours. The chart below shows the states with the greatest share of their urban Interstate highways considered congested. Data for all states can be found in the Appendix.  
  • The chart below shows the states with the greatest increase in vehicle miles of travel on their Interstate highways from 2000 to 2019. Data for all states can be found in the Appendix
  • The chart below shows the states with the busiest urban Interstates, as measured by average daily traffic per lane mile. Data for all states can be found in the Appendix.  

INTERSTATE FATALITY RATES AND SAFETY

The Interstate Highway System provides a network of highways with a variety of safety designs that greatly reduce the likelihood of serious crashes. Travel on the nation’s Interstate highways is more than twice as safe as travel on all other roadways.

  • The Interstate Highway System, which carried 26 percent of the nation’s travel in 2019, accounted for only 13 percent of the nation’s traffic fatalities as a result of superior safety features.
  • The features that make Interstates safer than other roads include a separation from other roads and rail lines, a minimum of four-lanes, gentler curves, paved shoulders, median barriers, and rumble strips to warn drivers when they are leaving the roadway.
  • Travel on the nation’s Interstate highways is nearly two and a half times as safe as travel on all other roadways. The fatality rate per 100 million vehicle miles of travel on the Interstate system in 2019 was 0.55, compared to 1.30 on non-Interstate routes.
  • The chart below details states with the highest traffic fatality rates in 2019 on their Interstate highways and the fatality rate on all other roads in those states. Data for all states can be found in the Appendix
  • TRIP estimates that the Interstate Highway System saved 6,555 lives in 2019, based on an estimate of the number of additional fatalities that would have occurred had Interstate traffic been carried by other major roadways, which often have higher traffic fatality rates and may lack the safety features common to Interstate routes.  
  • Based on TRIP estimates, the chart below shows the states where the most lives were saved in 2019 due to the increased traffic safety provided by the Interstate Highway System. Data for all states can be found in the Appendix.  

INTERSTATE TRAVEL AND ECONOMIC GROWTH

The Interstate Highway System is the backbone of the nation’s economy and has played a critical role in improving the country’s business productivity. Since 2000, the amount of combination truck travel on Interstates has increased at a rate more than double that of total travel on the system.     

  • The Interstate system carried 55 percent of all large commercial truck travel in the U.S. in 2019.  
  • Travel by combination trucks on the Interstate Highway System increased 43 percent from 2000 to 2019, while overall vehicle travel increased 26 percent. From 2010 to 2019, travel by combination trucks on the Interstate Highway System increased 14 percent, outpacing the 10 percent rate of growth for all vehicle travel during the same period. 
  • Travel by combination trucks, which are the large trucks that carry the majority of freight shipped in the U.S., accounted for 12 percent of all vehicle miles of travel on the Interstate Highway System in 2019.   
  • The chart below shows the states with the greatest share of Interstate vehicle travel by combination trucks. Data for all states can be found in the Appendix
  • Every year, $18.9 trillion in goods are shipped from sites in the U.S. 
  • Seventy-two percent of the goods shipped annually from sites in the U.S. are carried by trucks and another 14 percent are carried by courier services, which use trucks for part of the deliveries.  
  • The completion of the vast majority of the Interstate system by the 1980s, and the deregulation of the U.S. trucking industry, resulted in a significant improvement in the competitiveness of U.S. business.  The cost of moving freight, as measured by U.S. business logistics costs, dropped from 16 percent of U.S. Gross Domestic Product (GDP) in 1980 to eight percent in 2018.
  • The TRB report found that U.S. counties either on an Interstate highway or within 20 miles of an Interstate are anticipated to grow in population through 2060 at a rate approximately seven times greater than counties that are at least 20 miles from an Interstate highway (36 percent versus five percent).   
  • The Interstate Highway System has reduced travel times between destinations throughout the U.S. The improved mobility provided by the Interstate Highway System has given Americans greater choices about where they live, work, shop and spend their leisure time.
  • Forty-nine of the 50 top truck bottlenecks identified by the American Transportation Research Institute (ATRI) in its 2021 annual list of the nation’s top 100 truck bottlenecks are on Interstate Highways. The top 20 truck bottlenecks are listed below, with all 50 included in the Appendix

INTERSTATE FUNDING CHALLENGES

The U.S. Department of Transportation (USDOT) has determined that the nation faces a significant backlog in needed Interstate highway repairs and improvements.

  • The current backlog of needed improvements on the nation’s Interstate Highway System is estimated by the USDOT to be $123 billion.
  • The backlog on the nation’s Interstate Highway System includes $54 billion needed to improve pavement conditions, $37 billion to improve bridges and $33 billion for needed system expansion and enhancement.

The primary source of revenue for the Interstate Highway System is the federal surface transportation program, which was set to expire on September 30, 2020 and extended by one year by Congress to September 30, 2021. The program does not have a long-term and sustainable revenue source.

  • Signed into law in December 2015, the Fixing America’s Surface Transportation (FAST Act), provides modest increases in federal highway and transit spending. The bill also provides states with greater funding certainty and streamlines the federal project approval process.  But, the FAST Act does not provide adequate funding to meet the nation’s need for highway and transit improvements and does not include a long-term and sustainable funding source.
  • Revenue collected from the 18.4 cents-per-gallon federal motor fuel tax and the 24.4 cents-per-gallon federal diesel fuel tax are the primary sources of funding for the federal Highway Trust Fund, which distributes funds to state and local governments for highway and bridge repairs and other surface transportation improvements, including public transit, pedestrian and bicycling facilities.

RECOMMENDATIONS FOR RESTORING THE INTERSTATE HIGHWAY SYSTEM

Restoring and upgrading the Interstate Highway System to meet 21st Century transportation needs will require strong federal leadership and a robust federal-state partnership to reestablish the Interstate Highway System as the nation’s premier transportation network. The TRB Interstate report notes that “the scale and scope of the Interstate reinvestment imperative is daunting.” 

  • The following recommendations, based on the findings and recommendations of the TRB Interstate report, provide a roadmap for the restoration of the Interstate Highway System:
  • Reconstruct the nation’s Interstate Highway System, including pavements, bridges and interchanges
  • Improve safety features on Interstate highways
  • Right-size the Interstate Highway System by: 
  • upgrading some existing roadways to Interstate standard 
  • adding needed additional highway capacity on existing routes to maintain and improve mobility
  • adding additional corridors to accommodate demographic and economic growth 
  • modifying some urban segments to maintain connectivity while remediating economic and social disruption

Conclusion

Sixty-five years after President Eisenhower articulated a vision for the nation’s 20th Century transportation system, a Congressionally-mandated report has found that the U.S. faces a “daunting” task in restoring and renewing its most important transportation system.

The nation’s Interstate Highway System is beset with growing traffic congestion, increasing car and truck travel, and aging pavements, bridges and interchanges that need to be reconstructed and modernized.  

Today, the Interstate Highway System continues to save Americans time, lives and money while playing a critical role in supporting economic growth and enhancing the lifestyle choices of the nation’s residents and visitors.  

If Americans are to continue to enjoy the benefit of the unparalleled level of access and mobility provided by the Interstate Highway System, which has enabled the nation’s unprecedented development and growth, the U.S. will need to commit to a well-funded program of Interstate restoration, modernization and renewal.   

Ensuring that the Interstate Highway System plays the same role in supporting the nation’s development in the 21st Century will require a significant boost in investment in an Interstate restoration program based on strong federal leadership of a robust federal-state partnership.

As Americans look back on the many benefits that the Interstate Highway System has provided, they must also look ahead to meeting the challenge of providing a modern Interstate Highway System that will continue to enhance the quality of life of current and future generations

All data used in this report is the most current available. Sources of information for this report include:  The Federal Highway Administration (FHWA), the National Highway Traffic Safety Administration (NHTSA), the Transportation Research Board (TRB), and the U.S. Census Bureau. Cover photo credit: U.S. Geological Survey.

For the complete report visit trident.org