The Wisconsin Department of Transportation (WisDOT) owns and operates a state highway network of 12,000 miles, which carries approximately 80 percent of vehicle miles traveled in the state. Construction, maintenance, weather and other events often lead to lane closures or restrictions, causing inconvenience to road users. WisDOT developed numerous strategies for identifying alternate routes that drivers can use when highway travel times are affected by planned or unplanned events. Despite these efforts, WisDOT has observed that many alternate routes are underused, even when those routes would save travelers significant travel time. The objective of this project was to examine the decision-making processes of Wisconsin drivers regarding route selection, including their decisions to use (or not use) an alternate route instead of the highway network. Factors that were examined included how and when drivers make initial decisions about a preferred route, for both familiar and unfamiliar trips; the factors that influence their decisions to divert or not divert from their usual (or current) route to an alternate route; and the information sources they would most likely consult for travel and route information.

The purpose of this project is to maintain a safe and efficient flow of traffic over the Broadway Viaduct by providing a facility that meets Iowa DOT's current design standards for a principal arterial highway. The Broadway Viaduct is part of U.S. 6 connecting Council Bluffs, Iowa, and Omaha, Nebraska, and needs to be replaced to maintain the connectivity between the two cities. The project is located within the City of Council Bluffs in Pottawattamie County, Iowa. This Environmental Assessment evaluates alternatives for improvements to the existing viaduct and replacing the viaduct, with viaduct replacement identified as the preferred alternative.