The Interstate Highway System turned 50 this year, so it's no wonder many stretches of roadway--especially in heavily traveled urban areas- -are in serious need of fixing. In Missouri, the state Department of Transportation will soon be shutting down 12 miles of I-64 leading into St. Louis--the metro area's busiest freeway--for at least 3 1/2 years. Not surprisingly, many St. Louis residents are terrified at the thought of the traffic tie-ups to come. But if the experience of other cities is any indication, they'll survive the ordeal.

Several busy urban freeways have been completely or partially shut down for repair in recent years, including ones in Louisville, Minneapolis and Salt Lake City. State DOTs have pursued different approaches to traffic mitigation in each area, but certain ideas have become standard.

Some are technical, such as making sure not to close too many ramps near each other at the same time. But most are in the realm of public relations. Transportation officials have gotten better about providing regular updates on alternate routes and other coping mechanisms. Most plan extensive PR campaigns for big projects and send regular emails to drivers who want them. The Illinois DOT, which is reconstructing the Dan Ryan Expressway in Chicago, set up a Web site called filled with maps, live traffic images and weekly impact reports. In addition, about half of the country now has "511" traffic information phone capability.

Ultimately, of course, there's only so much that can be done to alleviate the pain of having several lanes of a major road taken out of commission. Some entrepreneurial real-estate brokers in St. Louis have been advertising the wisdom of moving homes or businesses to avoid the mess that the I-64 reconstruction will create. But Dan Cloar, president of the Downtown St. Louis Partnership, doesn't think the project will lead to disaster--at least for his central-city constituency. Downtowns generally end up suffering less than suburbs in these circumstances, since their grid patterns and mass-transit systems provide alternatives.

"When people find out what their alternatives are, it will go from being intolerable to being inconvenient," Cloar says.