Welcome to "Ask the Traffic Team," a Web page created to answer your everyday questions about statewide traffic issues. Each week we will feature three questions submitted by people statewide. The links to the left allow you to view questions about specific areas of the state, as well as search our archive of frequently asked questions.
If you'd like to submit a question to the Traffic Team, simply e-mail us and provide as much detail as possible. You can typically expect a response with a week.
Questions for the weeks of Feb. 5 - 19, 2010
I-5 restriping
Mark from Seattle wonders why southbound I-5 in Seattle has been restriped near the I-90 interchange. The right lane now becomes an exit-only lane, traffic now crawls along in just a single lane, and exiting the freeway takes forever.
I-405 glare screens
An I-405 driver wonders if WSDOT has considered installing glare screens along I-405 and SR 167 near Renton. Drivers are consistently looking into the bright lights of on-coming traffic, and it seems glare screens would make for a much safer ride.
Travel Time signs
An eastside driver wonders what time estimate the electronic travel times signs on I-405 refer to. Heading south on I-405, the signs show times to “Seattle” via SR 520 or I-90. Are the time estimates only for the time needed to cross the bridges, or are they estimates for how long it will take to get from that sign to Seattle?
Answers:
Q: Why did WSDOT restripe southbound I-5 near the I-90 interchange?*
The change in striping on the southbound I-5 collector distributor is a temporary lane shift to accommodate construction work on the left side of the freeway. It is not intended to improve traffic flow.
Crews are strengthening the piers that support the I-90 double-decker bridge that crosses over I-5 to better withstand earthquakes. Crews needed room on the left side of I-5 to safely work on one of the piers that is just a couple feet away from the left lane. Creating this safety buffer required that we shift I-5 traffic to the right and away from the work zone. This traffic shift leaves less space for lanes, meaning that Airport Way-bound traffic must stay in the mainline until the exit instead of merging over into an exit-only lane.
We understood that this would slow down traffic, but it enables us to complete an important safety upgrade on the I-90 bridges. We expect to complete work on the pier and shift traffic back to its permanent lane configuration by the middle of February. We expect to complete the project this summer.
*This question and answer came to us via Charles Brown and his Bumper to Bumper column in the Seattle Times.
Q: Wouldn't glare screens installed along I-405 in Renton make for a safer drive?*
We are installing 42-inch-high barrier on our construction projects on I-405, which is nearly 12 inches taller than the previous barrier. The taller barrier improves crash performance for larger vehicles and also has an additional benefit of shielding motorists from on-coming headlights. You may have seen the new, taller barrier on the majority of I-405 between I-5 and SR 167 and on SR 167 between Renton and Auburn. Crews will also install the taller barrier on the majority of I-405 between SR 167 and SR 169 as part of the Renton Stage 2 Project that will be complete in spring 2011.
The project plans for I-405 north of SR 169 to Bellevue are complete, but unfunded. We are currently pursuing funding options for construction. The vision for the I-405 corridor is a full retrofit of the freeway including wider shoulders and 42 inch high barrier.
So why were glare screens installed along SR 520? The conditions were relatively unique. SR 520 is one of the narrowest freeways in the region, with opposing lanes of traffic only four feet apart. Also, the lanes nearest to the median are general-purpose lanes, which can experience heavy peak-hour congestion.
*This question and answer came to us via Charles Brown and his Bumper to Bumper column in the Seattle Times.
Q: What do the times on the electronic travel time signs refer to?
The travel times on the electronic Variable Message Signs (VMS) predict the time it will take a driver to travel from that sign to the destination described -- in this case, Seattle. In the driver’s example, the sign incorporates the time needed to travel through Bellevue and across I-90. Additionally, when we calculate the travel times to "Seattle", we consider "Seattle" to be I-5 at University St.
You can find more detailed route information on our Web site at www.wsdot.wa.gov/traffic/seattle/traveltimes. Click on "route description" for each route to see more information about the definition of the route (for example, Seattle to Everett), and route length.
* This question and answer came to us via Scott Gutierrez and his Street Smarts column in the Seattle PI online.
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