DALLAS – The national network of interstate highways is becoming more congested and clogged, mostly with freight-hauling trucks, and is deteriorating due to a lack of investment, a transportation research group said on the system's 60th anniversary.
The 47,000-mile interstate system totals only 2.5% of the U.S. highway grid but accounts for 25% of national vehicle traffic, according to the report from TRIP.
The system was authorized on June 29, 1956, when President Dwight Eisenhower signed the Federal-Aid Highway Act, also known as the National Interstate and Defense Highways Act, into law.
After six decades, TRIP said, the interstate highway system is increasingly congested, with truck travel growing at a rate double that of overall interstate travel.
Travel by combination trucks on the interstate system grew 29% from 2000 to 2014 while all interstate vehicle travel grew by 14%, TRIP said.
Travel on the interstate system has been increasing twice as fast as new lane capacity, resulting in 43% of urban interstates being congested during peak hours.
California leads the list of most congested interstates, with too many vehicles on 85% of its urban highway mileage. Maryland is second with congestion on 75% of its urban interstate system, followed by New Jersey with 73%, according to the TRIP report.
Interstates tend to be in better condition than state-funded roads and bridges, TRIP said in its report, but the system lacks the required funding for needed improvements and repairs.
"An aging interstate system will increasingly require more long-term, costly repairs," the report said.
The Transportation Department estimates that the current backlog of needed improvements to the interstate system is $189 billion, said Will Wilkins, TRIP's executive director.
The backlog includes $100 billion of needed upgrades and expansions, $59 billion to restore the pavement that is being hammered by increasing numbers of cars and trucks, and $30 billion to bring interstate bridges to a state of good repair, Wilkins said.
Available funding for interstate renovation and expansion projects is only 61% of what is needed, he said.
"The long-term vision that helped establish the current interstate system 60 years ago is needed again today," Wilkins said. "Transportation investment and a sustainable, long-term funding source for the federal surface transportation program must remain a priority."
The interstate system has provided mobility for personal travel and cargo in every state, said Bud Wright, executive director of the American Association of State Highway and Transportation Officials.
The building of the national highway grid was a remarkable achievement that helped make the U.S. economy the world's leader, he said.
But large sections of the once fabulous roadways are in disrepair and some of the original bridges are still in use, serving heavy traffic loads long after their projected life spans have passed, Wright said.
"We must face the facts of where we are today," Wright said. "State departments of transportation are struggling to maintain their portions of this critical national network while demand keeps growing, even when many states have substantially increased their highway funding."
The $305 billion of federal funding in the five-year Fixing America's Surface Transportation (FAST) Act provides only a modest increase in spending through fiscal 2020, Wright said.
The interstate highway system is a national infrastructure asset that the entire country depends on, Wright said.
"As a nation, we must ask ourselves if we are taking care of that asset and increasing its value and the economic payoff it delivers, or if we are letting it languish and lose value," he said.