Houston's roads, skies and waterways saw increased traffic Tuesday as some of the city's biggest industries continued a slow march toward business as usual. United and Southwest airlines operated more robust schedules, oil tankers headed toward the shoreline and ship movements returned to nearly normal levels at the Port of Houston. "Things are getting back to normal," said Capt. Mike Cunningham, director of program management at the Greater Houston Port Bureau. "There are more and more vessel transits every day."