Q: During commutes from Snohomish County to South Seattle and then to the Eastside, Roger Harlow, who lives in Lake Cavanaugh, southeast of Mount Vernon, has been struck by the number of "out of service" Metro buses he's spotted in the far-left "fast" lane headed towards the Eastside on Interstate 90. He's wondered why so many buses make the trip empty, and why at some of the busiest times of the day?

To be sure, he's not alone in asking such questions.

Harlow's dad was a transit employee here for nearly four decades, he said. "So I understand the repositioning of buses for different routes." His gripe, though, is that so many buses travel the freeway slower than the posted speed in that left lane. "And as I pass them in the right lanes, I notice that the drivers are not in any Metro Transit uniform. They are in mechanic's coveralls."

Harlow suspects it's a mechanic taking a bus out for a test drive in the middle of rush-hour traffic, clogging up the freeway's fast lane. "This kind of activity needs to be scheduled for off-hour and maybe a route other than the freeways," he said.

And even if those times are because it's during that driver's normal shift, that's not enough reason, he says, to hold up traffic unnecessarily.

A: It's not unusual for Metro Transit's vehicle maintenance folks to drive buses between bases and to and from other Metro facilities, said agency spokeswoman Linda Thielke. "Sometimes it's moving buses base-to-base where there may be a short-term need at one base. Sometimes, the buses are being moved between the main body shop in Tukwila and back to the bases. There could also be the occasional test run either after repairs or trying to troubleshoot a specific problem where you need freeway speeds or conditions to check it out."

Recently, drivers on two Seattle-Renton routes reported problems with their coaches at higher speeds on eastbound Interstate 90. Thielke said vehicle maintenance staff tried to simulate those conditions with empty buses to pinpoint a problem. That may have been why Harlow spotted empty buses in the left lane, "because that's where those buses usually travel," said Thielke, "and they wanted to see if the road conditions had anything to do with the problems the drivers were reporting."

Nonetheless, Metro isn't convinced their buses are clogging up the freeway, said Thielke. Buses don't always have to return to base to switch drivers. Sometime drivers rendezvous with a bus at a designated point, using a county car to get there, then switching off with the driver being relieved, she said.