It’s raining as I write this which means many bicyclists in Chicago who want to travel over one of the 25 open metal grate bridges without a bike-friendly deck treatment have to decide: risk the slippery conditions on the bridge that cause your bike to feel wobbly and possibly fishtail, or ride on the sidewalk across the river.

A photo I took last night showing the new anti-slip metal plates over the bike lane on the Kinzie Street bridge. These plates cover the metal grates that make bicycling dangerous, especially when wet. 

Riders no longer have to make that choice today if they bicycle through the Kinzie Street protected bike lane as the Chicago Department of Transportation (CDOT) installed a metal deck over the bike lane portion of the bridge. This is the third bridge in two years that CDOT has treated to make bicycle friendly. (The ribbon cutting ceremony is Monday, July 25, at 11 AM, on the southeast corner of Kinzie and Jefferson.) The other two bridges treated recently are Harrison Street bridge in 2009, and Randolph Street bridge in 2011.

But we still have 25 more dangerous bridges. And CDOT knows this.

The beginning of a study

In 2004, CDOT hired T.Y. Lin International to study the inventory of metal grate bridges and their link to bicycle safety. The introduction of the report states:

These metal grate bridges…can be difficult and intimidating for a bicyclist to cross. Depending on the type and direction of the grating, grooves can cause a “channeling effect” or “sliding” for bike tires, and narrow tires can be lodged in gaps between the bridge grates. In addition, the metal can become increasingly slippery when wet, making these bridges even more difficult for bicyclists to safely cross in rain or snow.

The study’s goal was to determine what options are available to make these bridges “bicycle friendly.” (You may want to skip the middle section and read the conclusion at the end – what follows is a reprinting of several lists from the study.)

Rating bridges

Kinzie was rated a “bikeability” of “good,” as was Randolph. Harrison was rated “fair.” I might have rated every bridge “poor” because each of them is slippery, even when dry, and none provides the traction of an asphalt or concrete roadway.

Which bridges were rated poor?

• Webster (north branch, at Ashland)
• Cortland (north branch, at Elston) – deck has since been treated
• Chicago (north branch, at Kingsbury)
• Wells (main branch, at Wacker) – deck has since been treated
• North (north branch, at Kingsbury) – bridge has since been completely replaced
• Clark (main branch, at Wacker)
• LaSalle (main branch, at Wacker)
• 18th (south branch, at Canal)
• Loomis (south branch, near Archer)

The ratings were based on a formula that took into account deck type, grate orientation, percent deck was filled, and observed deck quality. The consultant used the ratings to prioritize bridges for treatment. After applying the formula, 15 bridges were rated as poor or fair. The consultant narrowed the list to find the bridges most in need of treatment by scoring the bridge higher if it was part of the bikeway network, and if it was already included in CDOT’s then-current (through 2008) bridge reconstruction or rehabilitation program. If it was included in the plan to be rebuilt, it was no longer prioritized.

Riding a bike over the treated deck of Cortland Street.

Priority bridges

The final list of prioritized bridges comprised 18th Street, Canal, Chicago, *Cortland, Halsted (North Branch River) and *Wells Street. This was curated from the bridges rated “fair” and “poor.”

The list below is excerpted from the CDOT 2003-2008 bridge reconstruction plan and includes only those bridges slated for construction, and their current status (in alphabetical order):

• 18th Street – Still bike unfriendly as of 2011
• Chicago Avenue – Still bike unfriendly as of 2011 (made worse in 2010-2011 because of a construction detour)
• Division Street at North Branch Canal – Still bike unfriendly as of 2011
• Division Street at River – Still bike unfriendly as of 2011
• Halsted Street at North Branch Canal – Currently under construction; it will have a concrete deck, a bike lane in each direction, and two main lanes in each direction.
• *Harrison Street – Has a bike friendly deck as of 2009
• Loomis Street – Still bike unfriendly as of 2011
• *North Avenue – Has a bike friendly deck as of 2008
• Van Buren Street – Still bike unfriendly as of 2011

Additionally, Canal Street (south branch) was reconstructed in 2010 but a bike friendly deck was not included in the result.

Conclusion

Of the 6 priority bridges, 2 were treated to have bike-friendly decks. Of the 9 bridges slated for reconstruction (some overlapping with priority bridges), 2 additional bridges were treated to have bike-friendly decks. (*Treated bridges have been starred above.)

The study assumed that bridges planned for reconstruction had designs in which it was too late to make bike-friendly changes, or that bike-friendly changes were already in the design – I don’t think either was true. Neither Wells Street nor Cortland Street were included in plans to reconstruct bridges yet later received bike-friendly deck treatments. This may have happened because of Kathy Schubert’s postcard-writing campaign to then-CDOT Commissioner Miguel D’Escoto, the commissioner at the time of this study.