A few days ago my column suggested tunneling Jefferson Avenue below grade at Woodward Avenue to allow Detroit to create an uninterrupted walkway from the new Spirit Plaza outside city hall to Hart Plaza and the RiverWalk.

Not everyone was pleased. Motorists thought the idea nuts, condemning any move to further restrict traffic flow downtown. And others pointed out the obvious challenges of burying a major street below grade where sewer lines and other utilities run. Yes, it's a very expensive proposition indeed.

Many readers suggested that a simple pedestrian bridge over Jefferson at Woodward would accomplish the same thing with less cost and less disruption.

Pedestrian bridges are everywhere, usually designed in a simple utilitarian form to get people from one end to the other over a highway. But a pedestrian bridge at Jefferson and Woodward would call for something more special.

Look no further than southwest Detroit for an example of what a creatively designed pedestrian bridge can look like. Crafted by the inFORM studio in Detroit, the Bagley Pedestrian Bridge and plaza connects the Bagley/Mexicantown neighborhood cut in two by I-75.

Then, too, the BP Pedestrian Bridge connecting Chicago's Millennium Park with its lakefront parks is a sinuous snaky bridge by architect Frank Gehry that drew widespread acclaim when it opened in 2004.

And there are numerous other examples around the world that show pedestrian bridges don't have to look like narrow cages but can create stunning architecture on their own.

Now, personally I would prefer tunneling Jefferson to connect Spirit Plaza with Hart Plaza. Despite the costs, it still strikes me as a more elegant solution to the problem.

But here's the point: Whether we tunnel under Jefferson or bridge over it, we've got to better connect the heart of downtown with the riverfront. Our vision for a more walkable downtown Detroit that would take advantage of our greatest asset, the riverfront, will never be complete without that.

The Futurama vision

Some history: At the 1939 World's Fair in New York, General Motors presented its famous Futurama ride and exhibit. It portrayed a city a couple of decades to come, sliced with expressways and ringed by sprawling suburbs. It was meant to provide a positive vision of a car-centric future.

No city embraced it more fully than Detroit. It rammed expressways through viable neighborhoods and built out new suburbs to the horizon.

And as part of that, when Detroit created its downtown civic center at mid-20th Century, it allowed the multilane Jefferson Avenue to slice right through it.

Some 80 years on, we have learned hard lessons of the car-dominated landscape portrayed in 1939. Pollution, traffic deaths and injuries, and the enormous waste of resources that comes with an ever-expanding suburban sprawl — these are the fruits of the Futurama vision.

More:Detroit needs to put stretch of Jefferson underground for more walkable downtown

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For many years now, urban planners have been trying to reverse the trend, focusing more on walkable streets and neighborhoods. Many cities have been ripping out some of their urban expressways and replacing them with surface streets designed with wider sidewalks, bicycle lanes and landscaping.

The Michigan Department of Transportation has already mapped plans to remove I-375 in Detroit, the mile-long extension of I-75 that runs down the east side of downtown Detroit. That should happen in a few years.

And elsewhere in Detroit, we have put many streets on "road diets," removing traffic lanes to create bike lanes, wider sidewalks and easier pedestrian crossings.

But not Jefferson yet

Up to now, that stretch of Jefferson Avenue at Woodward has resisted the trend. Jefferson at Woodward continues to serve as a commuter highway, so heavily trafficked that it requires several traffic cops to keep order at rush hour.

That creates a gulf between the increasingly walkable downtown and the riverfront itself.

Bridging Jefferson would help solve that problem. But it's only part of the solution. Hart Plaza itself needs a redo. The more successful design and programming of Campus Martius shows why.

Campus Martius, with scads of moveable furniture and a multitude of attractions from ice skating in winter to a giant sandbox in summer, shows how to create a lively enclave in the middle of a busy downtown.

Hart Plaza awaits that sort of lively reprogramming and redesign and may get it in the next few years. And the RiverWalk, probably Detroit's most successful urban planning effort of recent years, continues to expand year by year with more attractions.

But connecting all the pieces — Campus Martius, Spirit Plaza, Hart Plaza, the RiverWalk — remains incomplete.

Figuring out what to do with Jefferson at Woodward — a highway where there shouldn't be one — remains a major piece of that puzzle.

Contact John Gallagher at313-222-5173 or gallagher@freepress.com.Follow him on Twitter@jgallagherfreep. Read more on business and sign up for our business newsletter.