Q: Tom Wilson has a gripe about his commute between Bellevue's Eastgate area and downtown Seattle during the afternoon rush hour. He usually travels Interstate 90.

"I've taken the bus a few times to Eastgate, but it takes 90 minutes one-way, and it's usually very crowded," he explained. About one-third of his commute time is walking to and from bus stops and waiting for the bus. "Hardly an incentive, when it only takes on average a half-hour by car.

"I know I'm part of the problem," laments Wilson, who lives in the Roosevelt/Ravenna area in North Seattle. As a solo driver, he's watched vehicles whiz by him in I-90's carpool lanes. "I have no problem with that. Carpoolers have earned the right," he said.

But what about the empty double-length articulated buses he's spotted around 5:30 p.m. whizzing along in the carpool lane, with "out of service" or "return to base" displays showing? "What could be farther from a carpooler than an empty bus?"

Others have asked the same question: "Why can't those buses be in service, or at least wait until off-peak hours to return to the transit base?"

A: State law permits transit buses to use carpool lanes no matter the number of passengers on board, says Metro Transit spokeswoman Linda.Thielke.

When a bus is returning to base, it is usually because it is on the way to pick up a new driver or start another route, she said. "So, using the HOV lanes helps keep it on schedule to serve another set of passengers."

According to Thielke, many of Metro's buses cover more than one route or run in a single day, and those coaches can be on the road as long as 20 hours a day with different drivers. So, "out of service" to us doesn't necessarily mean out of service to Metro.