Wisconsin’s Plan to Reduce Traffic Congestion Is Moving in the Wrong Direction
Photo by Miguel Ángel Sanz on Unsplash
Wisconsin Governor Evers recently announced plans to revive the $1 billion expansion of I-94 west of downtown Milwaukee. This project was abandoned by Governor Scott Walker in 2017 due to cost concerns and significant opposition from groups concerned with racial and environmental justice. Proponents claim this expansion will reduce congestion, travel times, and air pollution. However, these claims are roundly refuted by the evidence. This stretch of I-94 is an important and highly trafficked roadway serving metropolitan Milwaukee and it should be repaired and maintained. Rather than expanding the interstate, to actually reduce congestion and travel times WisDOT should redesign this section of road to reduce the number of on- and off-ramps—from an astounding 26 to a more reasonable number.
Contrary to popular opinion, highway expansion does not reduce congestion. This idea was first proposed by Andrew Downs in the early 1960s and he termed it the “fundamental law of highway congestion”—namely, that traffic will increase proportionately as lane miles are added, resulting in no reduction in congestion. In the 2011 paper ”The Fundamental Law of Road Congestion: Evidence from US Cities”, the economists Gilles Duranton and Matthew A. Turner upheld Downs’ assertion, finding a one-to-one correlation between additional road miles and additional vehicle miles traveled. Most recently, Transportation for America released their report The Congestion Con, which details how, nationwide, we’ve spent the last several decades and hundreds of billions of dollars widening and building new highways in order to reduce congestion. However, this strategy hasn’t worked. Despite adding lane-miles at a rate that far outpaced population growth in the nation’s largest 100 urbanized areas, congestion has only increased by a staggering 144 percent!
Interestingly, the near-opposite is also true: removing lane-miles does not increase congestions. After the 1989 Loma Prieta earthquake, the Bay Area’s Central Freeway, which had carried 90,000 cars per day, was traded out for a multiway boulevard with a capacity of 45,000 cars. Despite the decrease in capacity there was no increase in congestion and notable positive effects on the neighborhood including lower noise and pollution levels.
Expanding I-94 will not reduce congestion or travel times. In fact, the evidence suggests they will likely get worse.
Neither can Wisconsin afford this project. The state spends too much money building highways and not enough on maintenance, public transit, or other state priorities. This I-94 expansion is estimated to cost $1 billion for a mere 3.5 miles of highway expansion. Although federal grants usually help pay for highway expansion, Wisconsin is on its own for maintenance. For example, federal funds generally make up about 25 percent of WisDOT’s budget but usually only cover about 0.3 percent of highway maintenance and repair. Moreover, gas taxes and user fees are insufficient to cover the state’s portion of WisDOT’s budget. This is why the legislature has been transferring money from the General Fund to WisDOT since 2013. General Fund money could be used to increase K-12 education funding, lower tuition for the UW System, or reduce taxes. However, because Wisconsin keeps building highways, we’ve had to divert $265.8 million from the General Fund to the Transportation Fund in just the last seven years.
“[Because] Wisconsin keeps building highways, we’ve had to divert $265.8 million from the General Fund to the Transportation Fund in just the last seven years. ”
Here’s another way to illustrate the financial un-sustainability of Wisconsin’s highway expansion: we continue to spend billions of dollars on highway expansion, yet, since 2013, we’ve spent more on debt service than on highway maintenance. For some better ideas of how $1 billion could be spent, we could build 22 high schools, 38 middle schools, or 10,400 tiny homes for veterans; we could reconstruct 1,612 lane-miles of city/village roads, or 588 lane miles of state highway.
Instead of expanding this 3.5 miles of highway, it should be redesigned to serve as the controlled access highway it was meant to be. According the Michigan Department of Transportation:
[A] Controlled-Access Highway is Designed exclusively for high-speed, unhindered vehicular traffic, with no traffic signals, intersections, or property access. These highways are free of any at-grade crossings with other roads or railroads, which instead use overpasses and underpasses to cross the highway. Entrance and exit to the highway is provided by ramps at interchanges…
I-94 is intended to be a controlled-access highway. Although the 3.5-mile segment that WisDOT proposes to expand technically meets the definition of a controlled-access highway, the 26 on- and off-ramps prevent this section of highway from actually functioning like one.
Image source: WisDOT
As Aries van Beinum et al. show in “Macroscopic traffic flow changes around ramps,” on-ramps create an area of increased traffic turbulence from 0.12 miles upstream of the on-ramp until 0.30 miles downstream; off-ramps create an area of increased traffic turbulence for 0.75 miles upstream of the off-ramp. In this section of I-94, westbound there are six on-ramps and seven off-ramps for a massively overlapping 8.19 miles of increased traffic turbulence in a mere 3.5 miles of highway. Eastbound there are seven on-ramps and six off-ramps for a similarly massive 7.44 miles of overlapping increased traffic turbulence. Van Beinum et al. also state that “turbulence has been shown to have a negative impact on both traffic safety and traffic operations.” These conclusions should come as no surprise to anyone who has driven this section of I-94.
Adding to this massive traffic turbulence, "75% of the trips along this segment of [I-94] either begins or ends within the limits of the project," according to WisDOT. So travelers are just hopping on and off the highway for extremely short trips.
If WisDOT is serious about addressing congestion on this segment of I-94 in an environmentally and fiscally responsible manner, they won’t add lanes. Instead, they will maintain and redesign it to have fewer on and off ramps.
About the Author
James Davies is the Executive Director at Bublr Bikes, Milwaukee's nonprofit bikeshare system. He's also an attorney and transportation advocate. James is committed to creating and advocating for transportation systems that work for humans and the environment. You can connect with James on LinkedIn and Medium.