Two years have passed since the Mike O’Callaghan-Pat Tillman Memorial Bridge opened over the Colorado River near the Hoover Dam. When it was built, the bridge bypassed 3.5 miles of hairpin-turn roads dotted with pedestrians. But few foresaw a major flaw in the project: When the new four-lane section of U.S. 93 opened, traffic jams formed in both directions on a 4.5-mile, two-lane uphill climb from the Hacienda to the traffic signal at Nevada Highway and Buchanan Boulevard in Boulder City. Boulder City Mayor Roger Tobler now hopes that highway designers can anticipate jams as they move forward developing U.S. ...