Smart Bridge across the Mississippi River

The new, ten-lane I-35W St. Anthony Falls Bridge carries the highway across the Mississippi River, just east of  downtown Minneapolis, Minnesota. The bridge is modern, it’s state-of-the-art, and it’s billed as ‘smart’, and if you have time to do only one thing during your visit to the city, take a look at the bridge.

C5FF0D18-275A-4BC5-B7D7-CAC34787F43E

Source: National Atlas of the US; US Dept. of Interior

If you’re not familiar with the area and you drive across the bridge, you probably won’t notice the bridge or the river. The bridge has no super structure above the deck and there’s little to differentiate the bridge deck from the highway. The transition from highway to bridge and back to highway is seamless. And whether you’re your heading north or south, you’ll be on a five lane highway and unlikely to get even a glimps of the river. To get a decent look at the structure, you must get off the highway, park your car, and walk.

Take any off-ramp leading to downtown Minneapolis. Your objective will be the West River Parkway. Several downtown cross streets connect to it. Once on the parkway, turn right and follow it to the riverside park called Bohemian Flats. There’s a pay-lot for cars within the park.

CF64407F-E7BA-449D-B967-18823934E845

Map shows I-35W Bridge in relation to West River Parkway and riverside parking lot.

The old eight-lane I-35W bridge collapsed suddenly on August 1, 2007 at 6:05 p.m. CDT, taking cars and trucks with it. Thirteen people were killed, many more injured.

232B3DD5-F609-435D-964D-036D554AED5B

The 35W bridge in Minneapolis seen the day after it collapsed. Image by Mory Gash/AP

Nancy Daubenberger, bridge engineer for the state at the time (now Assistant Commissioner for Engineering Services), speaking on NPR’s ‘All Things Considered’ August 1, 2017, ten years after the collapse, said this: “The shock that came over me, that such a large bridge like that could collapse . . . it was devastating and tragic and shocking; a very, very sad situation.”

Considering the importance of the I-35W river crossing to the state economy, a new bridge was designed and built in jig time. It opened September 2008, a little more than one year after the collapse of the old bridge.

63F3D198-5E1D-43EA-BCC9-D5E036C3D3A2

Old I-35W Bridge. Undated image from en.wikipedia.org

To see the new bridge up close, follow the footpath beside the West River Parkway, first under the No. 9 bridge (a former railway bridge, now a bike path), then under the four-lane, 10th Ave. bridge which crosses the river within 50 yards of the new St. Anthony Falls bridge. Follow the footpath a bit further and you’ll be standing directly under the I-35W and behind the bridge’s four south piers. This is where you can see that the bridge is in fact two bridges, side by side but separated by a few feet of empty space.

AB7D7697-BD33-4606-AD3F-435C22371FF0

Under the I-35W St. Anthony Falls Bridge looking north. Image by innovata/Wikimedia Commons/ CC-BY-SA

0E0B6613-A8E4-4015-80ED-8EB0562ED113

St. Anthony Falls Bridge at night. Image published by The Center for Transportation studies, U of MN.

Apart from its graceful lines and modernistic look, what makes this bridge a state-of-the-art ‘smart bridge’? Here’s an excerpt from The Catalyist, a publication of the Center for Transportation Studies, University of Minnesota.

During its construction, the [St. Anthony Falls] bridge was instrumented with more than 500 sensors that monitor strain, load distribution, vibrations, temperature, potential corrosion, and the overall movement of the bridge. Other sensors were installed to monitor the bridge’s security and control automatic anti-icing and lighting systems.

Although we can’t see any of these devices, we can imagine them constantly at work, transmitting information to the engineers responsible for the bridge’s wellbeing.

For side views of the New bridge, continue following the waterfront footpath to the Stone Arch Bridge, half a mile upstream. Built in 1883 as a railroad bridge and still standing firm after 135 years, the Stone Arch Bridge is now used only by pedestrians. The new I-35W bridge is designed to last 100 years.

 

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s