St. Louis isn’t special. I mean, in terms of traffic congestion. Most cities — most commuters — experience rush hours that do the very opposite of rush.

No surprise, then, that St. Louis’s Poplar Street Bridge gets clogged with the 120,000 cars that travel it per day. Also no shock: a new bridge has been proposed.

Commuters across the nation are now nodding their heads. We know what the citizens of St. Louis, Missouri, and East St. Louis, Illinois have to go through.

But a suggestion by a think tank in Missouri might cause a few heads to shake. In disbelief.

The idea? Make the Poplar Street Bridge a part-time toll bridge.

Southern Illinois University economist R. W. Hafer, writing for the Show-Me Institute, argues that another bridge might not even ease congestion. Why? By making commuting easier it would effectively lower the cost of commuting. When costs go down, demand grows, in this case even taking people off of public transit to drive their cars.

Putting a price on bridge travel, on the other hand — especially if the prices rise when demand rises — would encourage commuters to economize, and thus make the trek over the Mississippi easier for all.

As Hafer points out, if pricing “works for movie tickets, electricity, and seats at Busch Stadium, why not for space on the bridge during rush hour?”

Hmmmm. Maybe the reason we shake our heads is because we don’t expect reason to be applied to traffic.

This is Common Sense. I’m Paul Jacob.