From today's Post-Dispatch:
St. Louis commuters abandoned their side-street detours and secret shortcuts, returning to Highway 40 on Monday in numbers rivaling those before the lengthy rebuilding.
Missouri Department of Transportation officials said they expected displaced motorists to return gradually after the stretch between Interstate 170 and Kingshighway reopened early Monday. They just didn't think the cars would return so soon.
"The thing that probably surprised me was that people came back as quick as they did," said Ed Hassinger, MoDOT's district engineer in St. Louis. "We were thinking probably over the next few days people would start moving back. But it looks like ... they all came back today."
This report reminds me of John Seabrook's 2001 New Yorker article about traffic, which notes that highway construction doesn't necessarily reduce traffic, and can actually have the reverse effect:
No major new highways have been built around New York since the nineteen-seventies, partly because there's no room left, and partly because many people believe that building highways makes congestion worse, because drivers who had previously used mass transit to avoid the traffic begin using the new roads. Even if no new drivers take to the new roads, scientists have shown that increased road capacity alone can increase congestion, a phenomenon sometimes referred to as "Braess's paradox," after a German mathematician named Dietrich Braess. In the twenty-three American cities that added the most new roads per person during the nineteen-nineties, traffic congestion rose by more than seventy per cent.