Who knew the Kennedy Expressway’s reversible lanes were such an interesting topic?

The Chicago Tribune published an excellent piece on the reversible lanes recently that gives readers amazing insight into how they work.

These additional two lanes are switched twice a day. The lanes are inbound for the morning rush and then flipped for the outbound rush hour in the middle of the day during the week. On Friday nights an additional set of reversals are made to accommodate drivers headed into the city for dinner or a night on the town.

On weekends, reversible lane scheduling is based on festivals, sporting events and the like.

But according to the story, while the reversible lanes did alleviate traffic congestion in a significant way in the past, they are losing their impact. That’s because the Illinois Department of Transportation says the level of inbound vs. outbound traffic has been trending toward parity, compared to the past when traffic was heavier coming inbound in the morning and outbound in the evening.

While the morning commute still adheres closely to the traditional inbound rush hour traffic model drivers are used to, for some reason the evening commute is more symmetrical and is lasting later–until 8 PM most nights.

In fact, it seems the Kennedy is already operating beyond the capacity it was designed for according to IDOT. The expressway is supposed to be able to handle 225,000-250,000 per day. But the expressway is averaging 260,000 vehicles per day says IDOT.

So, the techs who oversee the operation of the reversible lanes from a command center in Schaumburg say it’s getting harder and harder to make the decision when to reverse the lanes and say, in rare cases, feel reversing the lanes may actually make congestion worse.

Read the full Tribune story for the entire compelling report, “As Kennedy traffic swells, reversible lanes lose their magic.”

Bonus Link: Check out the info laden graphic the Trib put together, “GRAPHIC: Congestion on the Kennedy.“

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