Will Parson’s proposed expansion of I-70 reduce congestion? Here’s what research shows

When Missouri Gov. Mike Parson proposed spending $859 million to widen I-70 to six lanes near Kansas City, Columbia and St. Louis as the first step toward expanding the highway across the entire state during his State of the State speech, lawmakers in both parties applauded.

Politicians across the political spectrum have long been drawn to highway expansions, with orange cones and fresh asphalt a time-tested way to demonstrate they can deliver for constituents. Kansas Democratic Gov. Laura Kelly, facing a tough reelection campaign, traveled to Louisburg in August to herald the start of construction on a project to expand K-68 in Miami County, for example.

But extensive research shows that expanding highways often doesn’t solve congestion problems over the long term, despite a strong desire among state and local leaders to lay pavement.

“Assuming there’s congestion, do roadway expansions work? The short answer is no,” said Jonathan Levine, a professor of urban and regional planning at the University of Michigan who studies transportation policy.

The idea that more road capacity in many cases does not permanently reduce congestion but can actually encourage more driving has been explored since at least the 1960s. Transportation and infrastructure planners widely acknowledge this concept, often called induced demand or induced travel, even as politicians continually seek to expand.

A 2019 study published in the journal Transport Policy estimated that “highway capacity expansion generates an exactly proportional increase in vehicle travel.” Whatever speed advantage drivers gained from expansion was lost within five years, the study said.

University of Toronto researchers, who reviewed interstate highway use in U.S. cities, found in a 2009 study that building out roads has no impact on the distances traveled by vehicles. Instead, more roads led to more driving, more activities that required driving and more residents.

While the researchers acknowledged alleviating specific bottlenecks can be helpful, they said their findings “suggest that an average extension of the interstate network does not result in sufficient travel time improvements to justify its cost.”

After highways are expanded, motorists who previously avoided peak traffic are more likely to drive during those times, Levine said, adding that drivers who previously avoided the highway altogether will also be more likely to drive on it. Others who limited their trips to avoid congestion will begin to drive on the highway more often, he said. In the long term, more highways may lead to more development, further adding traffic.

David Johnson, chair of the Kansas City Regional Transit Alliance, said the $859 million for the proposed expansion – or the several billion dollars it would take to expand I-70 throughout the state – could be put to other transportation-related uses, like rail service. Expanded Amtrak, for instance, would be an economic boon for rural areas, he said.

“I think the thing to remember is we have options and we need to explore those options,” Johnson said, adding that “what I would love for people to know is we don’t have to widen I-70 in three short sections with this money. It’s Missouri money. We can be using it for other infrastructure needs.”

Johnson also noted expansion will also require Missouri to buy at least some amount of land to accommodate the wider highway. The costs of those purchases can quickly add up.

“It may not be a lot for these sections that they’re talking about, but the point still stands – they’re going to acquire private property, convert it to public. That comes off the tax roll and that cost is probably part of their $859 million estimate,” Johnson said.

MoDOT spokesperson Linda Horn said Thursday that it’s too early in the process to know whether the state will need to purchase additional land.

Highway expansions under scrutiny

Parson’s proposal comes as states and localities across the country are grappling with whether to expand highways as the federal government delivers funding in the next few years under the $1 trillion infrastructure law passed by Congress and signed by President Joe Biden in 2021. Missouri is expected to eventually receive $6.5 billion to repair and upgrade highways, though the governor’s office has said the I-70 expansion will be paid for with state dollars.

Some localities have reconsidered the wisdom of highway expansions. Los Angeles transportation officials in May abandoned a long-running plan to widen a major freeway, and state legislators in California have weighed banning expansions depending on levels of pollution and poverty in affected areas. Highway expansions in urban areas have a long, checkered history, with often-white officials building in areas with large minority populations.

Parson has framed his I-70 proposal as a necessary response to congestion. The Kansas City-area portion of the project would center on an approximately 20-mile portion of highway between Blue Springs and Odessa – a stretch where the eastern edges of suburban development begin to bleed into more rural areas.

“For years, congestion, traffic accidents, and delays have become serious issues for commuters on I-70. Not only are we concerned for motorist safety, these inefficiencies are costly to our state’s economy. And we must invest to improve I-70,” Parson said in the State of State speech.

“To those who say we can’t afford it, I say we can’t afford not to.”

But the cost of congestion on Missouri’s state roads, which include I-70, are at record lows, according to a report from the Missouri Department of Transportation. The agency has calculated that in 2021, congestion costs statewide were $348 million, compared to more than $600 million in 2019, prior to the pandemic. Even though the decrease is attributable in part to the pandemic, MoDOT’s data shows that miles traveled now exceed pre-pandemic levels.

The report also suggests adding and expanding roads isn’t a congestion cure-all.

“A comprehensive look at congestion that goes beyond typical solutions of adding capacity is needed. Using smarter technology to help guide motorists is a must. Still, the desired outcome is to lower congestion costs and demonstrate that traffic is moving more efficiently,” the MoDOT report says.

MoDOT: taxpayers want expansion

MoDOT Director Patrick McKenna acknowledged the issue of induced demand during a briefing with reporters on Wednesday, but suggested concerns were inflated.

“There are both sides to that equation when it’s induced demand,” McKenna said. “I think that that has been exaggerated at a national level and it’s something that, you know, we have to be responsive to the taxpayers that fund the system itself. And they’re telling us what they want us to do with these dollars.”

McKenna said solving the “current problem” would be good for the reliability of the state’s transportation network and the safety of the traveling public.

Tom Crawford, president and CEO of the Missouri Trucking Association, said his group has been pushing to expand I-70 to six lanes for the last decade and wants to see more activity beyond Parson’s proposal.

“We think we have some opportunities here with some of the funds that are available to do some more investments,” Crawford said. “The ones the governor outlined are critically important, but it leaves some, at least some gaps and I think those gaps are going to be frustrating to folks driving up and down the road.”

Crawford rejected the idea that highway expansion can lead to more congestion. He predicted an explosion in the use of trucks regardless of whether the highway is expanded or not.

“I think it’s people looking for something because the projections we’re seeing — the trucks are coming. It’s just a matter of where they’re going to be and where do you want them,” Crawford said.

The expansion plan has drawn few, if any, vocal complaints from lawmakers, who had already been weighing options to widen I-70. State Sen. Bill Eigel, a Weldon Spring Republican exploring a run for governor, had previously proposed expanding all 247 miles of the highway in Missouri.

Missouri House Minority Leader Crystal Quade, a Springfield Democrat, noted the state’s role as a transportation hub centrally located in the country. “We do know that roads in our state are a huge issue,” Quade said.

Levine, the University of Michigan professor, said politicians repeatedly reach for new and expanded highways as a transportation solution because most people drive – and the concept of induced travel isn’t well known among the public.

“Political power tends to be concentrated in people who are able to drive and have no particular restrictions,” Levine said. “Political power is not concentrated in people who say, ‘gosh, my life would really be transformed if there were decent transit around here.’”