A convoy of buses, trucks and cars was scheduled to reach Omaha, Neb., today — approximately the half-way point of a 13-day cross-country trek commemorating the 50th anniversary of the signing of a federal bill to begin construction of America's interstate highway system. The convoy was organized by the American Association of State Highway and Transportation Officials (AASHTO). It departed San Francisco on June 16 and is expected to arrive in Washington, D.C., on June 29. Leading the convoy out of San Francisco was the Madden Cruiser, the MCI coach designed and manufactured for NFL broadcaster John Madden. Two other MCI coaches, sporting decals with patriotic and ecological themes, will travel the entire route. "We're proud to be a sponsor of AASHTO's celebration," said Tom Sorrells, MCI's president and chief executive. "This event provides an opportunity to spread the word that motorcoaches continue to offer an environmentally friendly, economical way to get from point to point." At the June 16 kickoff event in San Francisco, Transportation Secretary Norman Mineta said the 50th anniversary of the federal highway bill serves as a good reminder "that we must think about the next 50 years to keep Americans moving forward."