Challenging Traffic Projections
- raphie093
- 7 days ago
- 3 min read
Updated: 4 days ago
In conversations about what WisDOT should do about I-794, a common reaction to the removal-to-boulevard alternative is concern that vehicle traffic and congestion will increase and cause gridlock downtown. This concern comes from the assumption, which WisDOT uses, that vehicle traffic is like water; the volume will stay the same and disperse across the grid.
We agree with this assumption, in part. We also believe that the existing street-grid downtown and a well-designed multi-modal boulevard is capable of handling the dispersion of traffic, without causing gridlock, thanks to an urban planning phenomenon known as Traffic Evaporation.
The Flaw in the Modeling
WisDOT utilizes Vehicle Miles Traveled (VMT) modeling as a primary tool to capture vehicle traffic counts. The traffic counts then allow engineers to project crash and congestion data. The estimates presented in the Lake Interchange study are under another assumption: vehicle traffic will remain the same or may even increase, regardless of whether the elevated freeway remains or is replaced by a human-scale boulevard. When they use this rigid modeling tool, they overlook some key ideas about human behavior:
Induced Demand: As shown in the graphic below from Our Streets Minneapolis, adding lanes creates more traffic. When roads are built or expanded to make it "easier" to drive, people will opt to take more and longer trips, leading to cycle of increasing congestion. In other words, if you build it, they will come. And when I-794 was built, more people drove.
Traffic Evaporation: The opposite phenomenon is also true. As in the graphic below, also from Our Streets Minneapolis, Traffic Evaporation is the result from reducing vehicle lanes and converting the land to other uses; traffic levels actually drop. We saw this happen with the Park East removal. Today, McKinley Ave./Knapp St. sees about 16,250 vehicles daily on average, down from the 22,000 while Park East was up, and much lower than the projected 28,000-35,000.
How Traffic Evaporates
Vehicle traffic isn't as inevitable as drivers might believe. Rather, traffic and congestion are a result of individual choices based on the infrastructure that supports said choices. When transportation planning prioritizes people-centered design, we see mode shift and more balanced transportation.
Trips change: Drivers may adjust to a different, shorter route for regular commutes.
Exploring different modes: Improved infrastructure for biking, walking, rolling, and transit, in addition to the car infrastructure, makes the alternative modes more comfortable and more feasible to leave the car at home, especially for short trips. (Check out the The City of Milwaukee's Transportation & Mobility Plan to look at all of the ways Milwaukee residents already desire multi-modal improvements)
Land Use: Converting highway land, like the land under I-794, into taxable urban space creates a new opportunity to form a neighborhood where people can live, work, and play reducing the absolute necessity of a car and freeway travel to key destinations.
What does this mean for Milwaukee?
Using this flawed model, WisDOT is severely overlooking the potential for designing a safe, sustainable, economically viable, and multi-modal Milwaukee. We shouldn't be designing downtown based on outdated traffic models that don't account for how behavior changes when provided alternative options. Ultimately, denying transportation options undermines economic strength by prioritizing throughput rather than the connectivity and compatibility with the local plans and development.
Removing I-794 is an opportunity for the state to support the City of Milwaukee and Milwaukee County in activating a corridor, reclaim downtown for our residents, and increase safe, multi-modal options for everyone. We must move past this idea that traffic and congestion are inevitable. They are not and are created by ever-increasing roadways/freeways. Let's begin to shift toward public discussions to understand how it works and may benefit everyone on the roads.
