Why more WA drivers are going in circles

Washington's roadway overhaul unfolded quietly, at a few crossings where highway engineers hoped they could reduce crippling crashes, if they made drivers outside Bellingham, Lake Stevens or Marysville travel in circles.

The early projects succeeded, the word spread, and now there are 607 roundabouts around the state, twice the count as a decade ago, and fourth-most in the U.S.

Some are single-lane, others multilane agglomerations. They're rings, eggs, peanuts, teardrops, barbells.

When stop signs or signals are converted to roundabouts, the Insurance Institute for Highway Safety reports 72% fewer injuries and 35% fewer crashes overall, based on studies that include Washington state projects.

The ball started rolling in 1998, at a dangerous Highway 522 junction in Monroe where left-turn crashes were common, until it was replaced by a rare multilane roundabout in 2001, recalls Brian Walsh, then a Washington State Department of Transportation design engineer. There was a significant reduction" in injuries, he said. "The concept was proven, but it needed to be proven on a more regional level," he said.

A quarter-century later, three roundabout projects this year are reshaping how people drive in the Seattle area: dual circles bookending the Northeast 145th Street/I-5 overpass in Shoreline; a ground-level oval nestled within Kirkland's future triple-decked I-405 interchange; and Seattle's first roundabout, to tame Northeast 125th Street in the Pinehurst neighborhood.

These differ from the 1,066 small "traffic circles" that have blanketed Seattle residential streets, bringing drivers to a near-stop, for half a century. Unlike those, the roundabouts on arterials are meant to help traffic flow more easily in growth areas, while reducing speeds during potential crashes.

Nationwide studies find frequent fender benders at first, followed by long-term safety benefits, and sometimes reduced traffic delay.

Because drivers bend through at 15 to 20 mph, rather than zip straight through an intersection at 30 to 50 mph, severe injuries decline.

"They are excellent at reducing the likelihood of a bad crash - a fatality or serious injury," said Scott Davis, the WSDOT engineer who oversees roundabouts. "First, they reduce speeds. And they reduce the number of conflict points, and they're also, through geometry, bringing the driver's attention back to where they need to be. You can't really fall asleep and go into a roundabout. It takes away the possibility for a head-on collision."

The national count has passed 11,000 and some states, including Washington, Wisconsin and Virginia, have adopted a "roundabout first" policy.

"This is just a massive exercise in learning, that spreads back and forth across the country," Walsh said.

Here's a look at the area's three newest roundabouts, with a few navigation tips:

Shoreline's new traffic flow

A decade ago, city leaders reflected on the upcoming Shoreline South/148th light rail station, its park-and-ride garage, and transit-friendly apartments. Roundabouts were their answer. The old Northeast 145th Street/I-5 overpass was already miserable, and leaving it the same wouldn't work.

The job was supposed to be done last fall, but a design change to reduce the slope, and related utility relocations, prolonged the work.

For the average commuter, therefore, the greatest stress wasn't learning to maneuver roundabouts, but enduring the construction, shifting lane closures and even some spillover to an I-5 exit ramp.

The twin two-lane roundabouts opened the last week of June, following months of partial use. Except for sporadic landscape and signal adjustments, the delays should dissolve, said Tricia Juhnke, Shoreline public works director.

Shoreline is also sticking with traffic signals west and east of the freeway on 145th. Stoplights can "meter" the flow of cars, which helps other roundabout users (in this case, exiting I-5 ramps) find better gaps to enter, said Davis, the WSDOT expert. But the signals' mainpurposein Shoreline is to help travelers enter the 145th corridor, from a growing neighborhood west of the freeway, Juhnke said.

By installing roundabouts, plus an unimpeded right-turn lane directly from 145th into southbound I-5, the city asserts peak-time drivers will face only 36 seconds delay by 2035, instead of 3½ minutes.

Seattle's first roundabout

This month, the state's largest city will complete its first arterial roundabout, part of a broader safety initiative so people can walk, bike or bus more easily to the future Pinehurst light rail station, or be dropped off by friends who drive.

Seattle is a late adopter, partly because older streets and buildings, constructed at right angles, commit the city to a tight street grid, where land is scarce to create wider intersection circles.

But along Northeast 125th Street, just east of the station at I-5, the city already imposed a "road diet," shrinking road capacity from four lanes to two. That released some space to rejigger the crossing.

Seattle is adding arc-shaped concrete dividers and planting strips that protect cyclists on the perimeter of the single-lane roundabout. Meanwhile, triangular paved islands, known as chicanes, between the road lanes force drivers to slow down and veer right, before they circumnavigate the nucleus.

Pinehurst resident Daigora Toyama is glad the roundabout is helping slow cars that formerly reached 50 mph.

"When the light runs green, there was nothing to stop them," he said. "As a driver and a cyclist, I feel the roundabout helps us move more smoothly through the section. It will help with the natural flow of traffic."

However, he worries drivers won't notice pedestrians crossing Roosevelt Way, at the south spoke of the D-shaped junction. From the north side, drivers from 10th Avenue Northeast are blocked from the roundabout, and must right-turn toward I-5, "which is causing quite a bit of an uproar," he said.

Kirkland's asphalt complex

That big bulb under I-405 - among the most complex roundabouts in Washington state - potentially enhances safety, but that's not its main purpose.

WSDOT needed some way to move local Kirkland surface traffic within a triple-decker interchange now under construction, where Sound Transit buses and toll-lane ramps will go on level two, and the freeway on top.

A peanut-shaped roundabout (containing two circles) is what fits, and it opened May 12, with a few touches unfinished. There's another unit to the west that organizes traffic flowing down the hillside between I-405 and downtown Kirkland.

Though not unique, the layout demands vigilance, because both westbound lanes on 85th can zip past both halves of the peanut. If you've just exited southbound I-405, you must ensure both lanes are empty before nosing in. Otherwise, someone from the interior roundabout lane may cross lanes and nearly hit you as their car continues straight toward downtown Kirkland, instead of following the curve leftward toward the I-405 onramp and Bellevue.

Chances are, you'll witness a near-hit or someone honking, perhaps a semitruck warning others to steer clear. Temporary road markings this summer can be hard to read.

Thomas Huddleston, fleet manager at adjacent Lee Johnson Chevrolet, said despite "a general uneasiness" among drivers, the roundabouts replace stoplights where severe T-bones and sideswipes happened all the time.

"I think they're great, because as more people get comfortable with them, traffic will get better. But people need to know how to use them," Huddleston said.

A key to success is to locate signs and choose early which lane traces your path. The second priority is look left before venturing in. "You're always yielding to the left. No one's really going that fast. If everyone does that, there will be no anxiety," Huddleston said.

Track record

Washington roundabouts were among the most analyzed in the nation, but haven't been rigorously studied for a decade. Leaders consider their benefits well-documented already.

A study of 2009-16 data, by the insurance institute, found that in 540 multilane Washington state roundabout crashes (four per year per site), only 18, or 3%, resulted in injuries. Total crashes declined 9% per year on average, and injury crashes also lessened, indicating that drivers got safer with experience.

As for public sentiment, the institute found that along Guide Meridian outside Bellingham only 34% favored two roundabout conversions before construction, but 70% supported it a year after opening.

Pedestrian risk?

Two-lane roundabouts can produce so-called "double-threat" crashes, if the first car stops at a crosswalk, and the second driver rolls though and strikes someone.

(Seattle and Shoreline, among many cities, have been getting rid of unsignaled double-lane crosswalks, since a 2002 double-threat crash in Shoreline killed a 13-year-old girl in a crosswalk on straight 15th Avenue Northeast. The Northeast 145th Street roundabouts goes against this trend.)

Walsh, who was recently chair of a national roundabout-standards board, said conventional intersections create more risk, because drivers make fast left turns, or turn right on red, without noticing people on foot. The roundabout realigns traffic, so "the sight lines are more direct and more forward, he said, compared with drivers making an intersection turn.

Shoreline will rely on flashing amber beacons, a national design norm, to encourage all drivers to stop safely at crosswalks.

By early 2027, a steel-arched walk-bike bridge will be assembled over I-5, connected to Shoreline South/148th Station. People in new apartments west of the freeway, and students walking between the station and Lakeside School, can skip the multilane roundabouts.

In Kirkland, there aren't any crosswalks in the 85th Street multilane roundabouts. Instead, new walkways will lead to bus stations on the I-405 interchange's second level, and to crosswalks near the toll lane entrance, in a couple of years.

Traffic revisions ahead

Will roundabouts continue to spread? Yes.

Some settings, especially Aurora Avenue North, exceed 40,000 daily vehicles, too many for roundabouts, said Walsh.

The insurance institute says they're a poor fit where one direction of traffic greatly exceeds the others. In Washington, they're uncommon where large numbers of people walk.

More are coming anyway, because roundabouts are so adaptable to many kinds of roads, said WSDOT's Davis.

Intercity Transit in Lacey is designing a circle so buses serving busy Martin Way can U-turn near the end of the line more easily than using stoplights.

Walla Walla cut the ribbon in mid-June for its second roundabout on four-lane Highway 125, which further breaks up a 50 mph corridor where many drive even faster. Prosser just approved its first roundabout, to replace stop signs where a farmland route crosses the town's dominant Wine Country Road.

Kirkland isn't done building roundabouts either. By the time I-405's three-layer interchange is finished, toll-lane drivers and buses at the middle level will encounter yet another roundabout in the sky.

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This story was originally published July 8, 2026 at 6:43 AM.