Q: Michael Butler of Issaquah says he's a firm believer in the benefits of freeway ramp meters. But he questions whether there's a pattern to the metered on-ramp to eastbound Interstate 90 at Bellevue's Eastgate-area interchange.

"I take this way home every night (usually between 5 and 6:30 p.m.), and it doesn't seem to matter what time I pass through, the on-ramp is sometimes on and sometimes off.

"There doesn't seem to be any kind of pattern. As you can imagine, when the meter is off, traffic is a mess. Not only was the ramp backed up onto side streets, but the freeway was also congested, as there were too many cars trying to merge at one time," he said.

"One would think that the meter should be on at regular intervals every day. What's the reasoning of the timing?"

A: Martin Dedinsky, the state transportation department's freeway operations engineer, says ramp meters automatically adjust their timing based on how heavy traffic is on the freeway. And that's to maximize traffic flow on the freeway, and on the ramp.

Traffic engineers also monitor ramp meters from the state's traffic-management center in Shoreline, and can turn ramp meters on or off and adjust meter timing when needed, he said.

If traffic is too heavy on I-90, vehicles from the on-ramp are unable to merge and traffic backs up all the way up the ramp to the ramp meter. When that happens, traffic engineers turn off the meter because it is no longer effective and will cause ramp traffic to back up onto city streets, said Dedinsky.

"The on-ramp is frequently overwhelmed by increasingly heavy traffic on I-90 and coming from several city streets," he said. "In fact, this ramp experiences some of the heaviest traffic in the Puget Sound region because of rapid growth in the Eastgate area and in communities further east."

But Dedinsky says the DOT continues to monitor the ramp closely and look for ways to improve traffic flow. "One possible option," he said, "would be to change the HOV (carpool) bypass lane on the right to a metered general-purpose lane to give the ramp more lanes to store waiting vehicles."

Carpool-lane users could use the newly-constructed direct-access ramps at 142nd Place Southeast, just west of the Eastgate interchange.

That area also is one of the spots the DOT is studying as part of its route-development plan for I-90 between Bellevue and North Bend. That study, Dedinsky said, should be finished next spring. But any changes would be spread over the next 20 years as funding becomes available.