MoDOT is worried about traffic issues that may result from the replacement of I-70 downtown with an urban boulevard as proposed by City to River. From an STLtoday Road Crew discussion:

Linda Wilson: [MoDOT’s] position is that after we build the new Mississippi River bridge downtown, there will still be a demand of 50,000+ vehicles per day to drive the section of highway that runs in front of the Arch. […] We have told the groups that if they can develop a plan to accommodate how these 50,000+ vehicles can get through, we are open to looking at it.

In response, City to River wrote a blog post with examples of urban boulevards around the world that currently handle 50,000 vehicles per day or more. In all likelihood, however, a re-imagined Memorial Drive will not be burdened with such high traffic volumes.

Conceptual Math

Road realignments proposed by McEagle’s Northside project may reduce the traffic burden on a new Memorial Drive. // NorthSide.

Take 50,000 vehicles on I-70, then remove the highway and replace it with an urban boulevard. The result is less than 50,000 vehicles on the new Memorial Drive.

The devil, of course, is in the details. How much of I-70 is removed? How do the stub ends of I-70 and I-55 connect to the street grid? Will any other streets get realigned as part of the highway removal project? Only a full fledged traffic study can predict how much traffic would travel along a reworked Memorial Drive. But the answer will invariably be less traffic than there is now. Just like in electrical systems, if you add resistance to a network, some traffic will scatter looking for alternate routes of travel.

Quick Look at Portland

Waterfront Park and Naito Parkway in Portland, Oregon. Waterfront Park was created from land occupied by a former highway. // freddy and Greg_e.

Portland is one of the most frequently cited cities when it comes to highway removal and for good reason. In 1974, Portland closed and removed the the four-lane Harbor Drive freeway. In its place, the city built Waterfront Park and now enjoys unhindered access to a green oasis and its riverfront.

Prior to Harbor Drive’s closure, traffic engineers warned that closing the freeway would cause unprecedented congestion. The Portland City Council was convinced otherwise. The freeway was closed and… nothing. Traffic appeared to be just as if it were any other day. Sound familiar?

All in all, the worry about how to accommodate traffic from I-70 may well be much ado about nothing.

Posted by Herbie Markwort

I like to write about transportation.


  1. JN, I understand your concern about intercity through traffic, but that is not a concern with St. Louis and it's future highway network. With the completion of the new Mississippi River bridge in 2014, through traffic will be able to remain on I-70 and never pass through downtown. After the bridge's completion, all traffic remaining on the downtown segment of highway will have a local origin or destination. With the closure of I-70, it may be a little less convenient for someone to get from Carondelet to Old North St. Louis, but it's a minor inconvenience for an improved cityscape.

  2. Have any freeway removal projects succeeded in the middle of the country?I'm aware of Portland and San Francisco's projects, but they're both a bit different than St. Louis in that they don't have any through traffic. Once you hit the waterfront in Portland, you just can't keep going in a car, unless your car happens to be amphibious.I just recently completed a cross-country drive (moving a friend from SF to Brooklyn), from one end of I-80 to the other. It would have been really unpleasant if the freeway suddenly became an urban boulevard through each city, and I bet long-haul truckers would agree. I'm not familiar enough with STL to know if there's sufficient provision for long-haul through traffic in the city's freeway network, but I can imagine this being a significant concern.

  3. Why do traffic engineers continue to dismiss the proven phenomenon of induced demand?Building or preserving an urban expressway with the intention of loosening the load on local streets is akin to putting out a dish of rat food so that rats will stop going through your trash. The bowl of rat food (expressway) is just going to attract more rats (traffic) to the area in general, and there will be that many more rats around to infest the garbage (local streets).

  4. "Have any freeway removal projects succeeded in the middle of the country?" Yes! Milwaukee Here is a brief synopsis on CNU's site: and a page from the city's development department that outlines development potential:

  5. I forget the citation, but its been proven that traffic acts as a gas not as a liquid like most people assume. The more road, the more cars!!

  6. And we should add, the less road, the fewer cars. But in this case the cars present would actually be better able to access downtown St. Louis.

  7. I'm for the rerouting of I-70 out of downtown. Really, its just a decaying eye sore and downtown could really do something with the riverfront if it was gone. Besides alot of people will probably end up using the posh I-64 as the main route to get thru St. Louis instead of industrial I-70

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