February 14, 2000
A graphic portrayal of a roundabout, proposed by City of Woodinville engineers last week as another alternative for resolving congestion at the Hollywood intersection.
by Marshall Haley, staff reporter
WOODINVILLE--An alternative that promises more consistent and safer traffic flow and better business access at the Hollywood intersection will be seriously considered by Woodinville's City Council.
Public Works Director Mick Monken led an audiovisual presentation of a two-lane "roundabout" alternative for the intersection, which currently rates an "F" on the federal A-F descending scale of traffic flow efficiency. An "F" means the average car spends more than 60 total seconds at a standstill before clearing an intersection.
That seems an almost laughable understatement for any northbound, rush-hour locals who have spent 10-15 minutes crawling from the Molbak's greenhouses just north of NE 124th. But studies show a roundabout would immediately improve an "F" rating to a "B," or an average stopped delay of only 5-15 seconds, said Joe Seet, City Traffic Engineer.
"That might still mean slow going, but it's a difference between drivers getting frustrated by a steady crawl to going ballistic over a series of complete stops," said Seet. "A roundabout is not the answer for every intersection, but our initial study shows that it has the potential to improve this one. You must realize that stoplights create longer queues in the first place. Even speed limits of 40-45, such as on SR-202, do not prevent serious rush-hour backup caused by traffic signals, because the number of cars entering the intersection during rush hour is much higher than the cars being released by the signal."
More importantly, the computer-generated studies show the widened road with a roundabout would move cars through the intersection much faster than a conventional signal, based on projected traffic volumes for 2001 and 2010. That's even without a possible widening of the entire length of the Redmond-Woodinville route before 2010.
Many people might have to see a roundabout work to believe it. A video on roundabouts showed a queue of 10 cars waiting for access to a roundabout: only 30 seconds transpired from when the first car stopped until the tenth car entered the roundabout. At a signal intersection, all ten cars could have still been waiting for the light to turn green.
The Hollywood intersection joins the Beardslee Blvd.-NE 195th-112th NE intersection, just west of I-405 in Bothell, as candidates for roundabouts involving state routes. The state is working closely with Woodinville and Bothell in considering those plans, said Seet. Roundabouts recently built in the region include one in University Place, south of Tacoma. Another is planned for SR-203 at NE 124th in Duvall.
When Seet worked for the state, he was instrumental in the development of the region's first roundabout on West Lake Sammamish Parkway SE at I-90. The state has determined that the roundabout has more successfully moved traffic through that area than before, when rush-hour traffic made access to the westbound I-90 onramp from the stop sign at the east leg of West Lake Sammamish extremely difficult. The roundabout reduced four lanes on that north-south arterial down to a single counterclockwise lane. Councilmember Carol Bogue visited that roundabout last week and said she was amazed at how well it moved rush-hour traffic.
The Hollywood roundabout alternative would have two circular lanes, and--as in the other alternatives--would still incorporate the widening of all four legs of the intersection by two lanes, extending over 800 feet on the north and south legs.
Roundabouts differ from the much larger "traffic circles" more common in the eastern U.S., in that cars entering a roundabout must yield to the traffic in the circle. Many people initially assume roundabouts will increase congestion, since they are designed to slow traffic to 20-25 mph, said Seet. But studies have proven the opposite. The roundabout gives the City one more option to consider before the project design starts this spring. It is one of five types of intersection control which also includes: a no-control option; yield signs; stop signs; and signal lights.
Traffic circles have such a large circumference they cannot be called true intersections nor intersection control options, because the roads entering them are so far apart, said Seet. Traffic circles do not require entering cars to yield to cars inside the circle, as do roundabouts. Instead, cars already inside traffic circles must yield to entering cars.
"The main complaint you hear from drivers in a traffic circle is, 'I can't get out!'" said Seet. "You might have to go around two or three times before you can get into the outside lane and onto the street you want. A roundabout is very flexible to volumes and driving characteristics of individuals--it is very forgiving."
Roundabouts eliminate off-peak sitting at a dead stop waiting for the light to complete its cycle, even when no cars are coming the other way, said Seet. Even "triggered" lights require some stopping time, waiting for the light to cycle through the other directions. Another roundabout advantage is that drivers only need look to the left before entering the circle, because once a car is inside, anyone entering the roundabout must yield to all cars in the circle.
In addition to the 20-25 mph speed forced by the design, the island in the middle provides a major safety factor: it eliminates accidents caused by drivers running red lights. Studies in several European countries and Australia show accident reductions between 35-78 percent at intersections converted from signals to roundabouts.
Hollywood Schoolhouse owner Jim McAuliffe and Chevron owner Tony Shahen expressed enthusiasm over the improved access a roundabout would give their customers. If the stoplight alternative is adopted, and three lanes are added to each leg, all turns across the left-turn lanes would be prohibited.
A roundabout would eliminate cars' having to cross lanes to head in the desired direction, if customers made all right turns to enter or exit businesses on three of the four corners. To exit the businesses, they would simply turn right, go into the roundabout and right exit on the leg of their chosen direction. That would especially help access to the Chevron, currently blocked from eastbound traffic by a road divider.
Access for the business complex on the southwest corner could be maintained with minimal impact. With the left turn lane eliminated on the northbound leg, drivers headed for those businesses could sit in that lane while waiting to merge.
Safety would also improve for pedestrians, said Seet. The flared-out islands at the yield points allow pedestrians to only worry about cars coming from one direction at a time; and the island provides a sanctuary for pedestrians, without a need for crossing signals.
Before leaving one side of the street, pedestrians would make eye contact with the car on their left, allowing it to stop before they walk to the island. Once at the island, pedestrians only need worry about cars on their right. The island crossing area is a little more than one car length behind the intersection's yield line. The second car often must stop anyway to wait for the first car to yield, making eye contact between that car's driver and pedestrians easy. The island "rest stop" makes crossing especially easier for slower walkers and people who can't easily traverse a 30-foot crossing without resting halfway.
At a standard stoplight intersection, pedestrians must watch for cars from four directions, including anyone who might run a stoplight on their left. A large percentage of pedestrians are typically hit by cars making a free right, said Seet. Those drivers are looking for oncoming traffic on their left, and forget to check for pedestrians on their right before accelerating.
"After seeing this presentation, I think a roundabout could give a positive gateway statement for our tourist district, and I like the better business access," said Councilmember Barbara Solberg.
"I wasn't in favor of this before seeing the visual demonstration, but it looks like it has good potential," said Councilmember Bob Miller. He admitted he had thought roundabouts were the same as the traffic circles he had bad experiences with in Europe.
Mayor Randy Ransom said he liked the added safety factors and dramatic service increase from "F" to "B." On behalf of the Council, he directed Public Works Director Mick Monken to have his staff complete the roundabout study, comparing all factors to those of a conventional intersection.