Thursday, March 12, 2020

What's going on with Seattle area traffic with COVID-19?

March 30-April 3
Traffic volumes still show decreases compared to February, reaching a steady new normal for Seattle-area routes in the wake of Governor Inslee’s shelter in place order declared in March.

By Friday, April 3 traffic along the I-90 floating bridge fell by 62 percent and on SR 520 by 76 percent compared to volumes in February.

Traffic along I-5 in Everett fell by 54 percent, and by 53 percent through downtown Seattle. Routes along I-405 kept with the trend with volumes decreasing by 58 percent in Bellevue and 53 percent in Tukwila.

March 23-26
Traffic volumes continued to decrease after Governor Inslee’s shelter in place order on Monday, March 23.

By Friday, March 27 traffic volumes on the I-90 floating bridge decreased by 65 percent and on SR 520 by 77 percent compared to numbers in February. Traffic along I-5 in Everett continued its downward streak, falling 56 percent while traffic on I-405 through Bellevue declined by 60 percent.

Monday, March 16 through Friday, March 20
Driving south from Everett to Northgate, traffic volumes are down 30 percent, and 36 percent between Northgate and downtown Seattle compared to traffic volumes in February. This was especially noticeable during the A.M. commute with overall traffic volumes down by 41 percent as of Friday, March 10.

South of downtown, traffic volumes also fell throughout the week with peak decline on Friday, decreasing by 32 percent.

Traffic in Bellevue along I-405 fell by roughly 35 percent, with decreases along the ends of the freeway in Bothell and Renton — both of which saw reductions near 30 percent compared to February volumes. During the same time period, traffic decreased by 45 percent on the I-90 bridge and 60 percent along SR 520.

Tuesday, March 17
We are seeing a sharp decrease on all Seattle area highways. Although we do not yet have exact figures for Monday, travel times were well below average during the typical peak commute periods. This includes I-5 between Everett and Seattle, which saw trips taking 30-40 minutes during the morning and afternoon drive times. That’s roughly a 50 percent drop from normal conditions.

In looking at the previous week, the daily average volume dropped about 10 percent in the region compared to February. The largest decrease was along SR 520, which saw 30 percent fewer vehicles.

By DiAngelea Millar

As many large employers in King and Snohomish counties encourage teleworking and school districts take the classroom to the cloud because of COVID-19 concerns, we started fielding questions about the affect those changes had on the morning and afternoon commutes.

It's too soon to call what we're seeing a "trend"- technically, trends require lots of time and data, but as the weeks march on it's pretty clear the demand on the highway system is lighter.
Left: The light morning commute through the middle of downtown Seattle on Thursday, March 12 shows how much traffic has been affected by people staying home due to the coronavirus. Right: A look at I-405 in Bothell during
the peak of the morning commute on Thursday, March 12.

As we watch the roads and collect travel information over the coming weeks, we'll continue to update this post.

Let's start with the first week of March
Traffic volumes (a measurement of the number of vehicles on a section of roadway during specific time) in early March were consistently average as were the length of backups. Interestingly, the backups cleared faster than usual.

Wednesday, March 4

Traffic patterns showed lower than average travel times, with commutes 5-30 minutes quicker than normal. This was most apparent on southbound I-5 between Everett and Seattle. With the decrease in travel demand, the amount of vehicles making use of the highway system more closely matches the capacity of our roads. Simply put, we weren't seeing as much congestion with fewer cars on the road.

Friday, March 6

It doesn't take much to bump up the commute times, even when there are fewer vehicles on the roads. Case in point was northbound I-5 into Seattle. Wet roads and blocking incidents created a blip in our seemingly easy commute week. A crash involving a truck that spilled oil closed two left lanes in downtown Seattle but cleared before 7 a.m. Commute times from Federal Way to Seattle were 30-40 minutes higher than usual.
A look at traffic graphs from Wednesday, March 4 shows a significant change in traffic congestion. The vertical axis shows travel time in minutes, the horizontal shows time of day. The 90th percent line indicates the top 90 percent travel
times on that route and the 10 percent line is an average of the lowest times on that route.

Now on to the second week of March
The week started off with low traffic volumes and travel times. 

Monday, March 10

Traffic volumes decreased by 4 percent on southbound I-5 between Everett and Seattle. On the same day, northbound I-405 traffic between Renton and Bellevue decreased by 8 percent. It may not sound like much, but the difference between a smooth commute and a rough one is at the margins. Any specific drop in traffic demand, especially during the peak periods, can result in a noticeable improvement in trip time.

With slightly fewer cars using our roads, vehicles can move faster with greater spacing. This makes it possible to prevent traffic-flow breakdown, essentially the point when there is more demand than carrying capacity, which results in backups and delays and fewer vehicles getting through each lane. Additionally, it took less time for normal speed to resume following a blocking incident like a crash or stalled vehicle, especially during peak travel times.
Highly unusual to see travel times at or below average on these routes from these
travel times at 8:40 a.m. on Thursday, March 12.

Fewer vehicles in toll lanes
We've seen a decrease in traffic on our toll roads, although it is too early to tell how this will impact revenue long-term.

What does this mean?
Many factors affect travel times including weather and blocking incidents. But work and school schedules also affect demand on our highway system and if schools are closed or people work from home, we can see the result of this in our travel times and traffic volumes.

Stay tuned. As we gather more data over the next weeks and months, we'll update this blog with additional information.

This is a great time to plug a couple of our useful tools to keep in your back pocket. Check our statewide travel alerts, Twitter accounts and the WSDOT App for the most up to date traffic information. As outlined above, commutes can turn on a dime and it's in our best interest to be an informed traveler.


Unknown said...

Maybe our local representatives can create a mandate to make any company that employs 1000 or more to allow them to work from home once a week. It would allow WSDOT to fix the thousands of potholes and cracks correctly, without disruption to commuters.

Unknown said...

Traffic great, yet as we all know what's happening, It brings a very very eerie feeling. Just not normal! Especially if you have been commuting
For well over 15 years. This is not normal, yet scary! What's Next

Unknown said...

Very interesting. May shed light on future opportunities for Washington State.

Adina said...

Now that we have seen what is possible, I don't think we should overinvest in absurdly wide highways and boulevards anymore. The teleworking should stay for good, as we have been desperately needing it to combat climate change. And then we can put all that road money into projects that facilitate greener transit methods like buses and the rail. I don't say this lightly, but thank G_d for COVID showing us what is possible when the rich tech owners feel the same dangers as the poor. The virus should be elected president.

Karlan Brekne said...

With the obvious recent reduction in traffic on our highways and interstates, it's obvious that the employees of large tech companies directly contribute to the usually awful travel times in the morning and afternoon hours throughout Snohomish, King and Pierce counties. Perhaps Sound Transit, State and Federal governments should look to taxing the large tech companies in order to fund the light rail and roadway improvement projects instead of over taxing vehicle owners through tab fees based on over-inflated vehicle values, taxes on fuel per gallon and additional tab fees for EVs.

Bobisbad said...

You certainly are emblematic of the hateful insanity pervading our society.

Elizabeth said...

My husband sailed through the Maltby light this morning going to Costco at 7:45am and coming back at 8:45am. He could not believe it! He was very happy! Unfortunately the Maltby light mess will return,but in the meantime, it is wonderful.

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