Wednesday, September 30, 2015

I-405 travel times show first commutes in regular lanes are close to normal

By Kris Olsen

After several days of operation, the new Interstate 405 express toll lanes are working well. They began providing a fast and reliable trip immediately to drivers and transit users. Our traffic engineers are also keeping a close eye on I-405’s regular lanes to see how traffic is moving.

We’ve closely watched travel times during the morning and evening commutes the past few days and compared them to travel times from October 2014.  We’ve taken their information and plotted them on the charts below. So far, the results are encouraging.

The morning commutes

First, let’s explain what’s on the graph.
  • The solid black line shows the average weekday morning commute time in the regular lanes for October 2014. That’s our “baseline,” if you will. 
  • The black dashed line shows a very heavy commute drivers experienced once out of every 20 days in October 2014.
  • The blue line shows the southbound commute for Monday, Sept. 28. 
  • The purple line shows Tuesday morning’s commute.
  • The yellow line shows Wednesday morning’s commute.
On average in October 2014, the morning commute in the regular lanes generally peaks just after 7 a.m. with a trip between Lynnwood and Bellevue taking about an hour.

Now, compare that to Monday, Tuesday and Wednesday.
  • On Monday, the blue line, the average commute time in the regular lanes peaked at 65 minutes right around the 7 a.m. hour. 
  • On Tuesday, the purple line, the southbound commute in the regular lanes was slower compared to October 2014. It peaked just below 75 minutes at 7:30 a.m. But, that also coincides with a collision that occurred at Northeast 70th Street. About 90 minutes later a second collision occurred near Northeast 108th. 
  • The commute on Wednesday morning showed travel times in the regular lanes were much lower than average. 
And take a look at the black dashed line. That shows a commute in October 2014 that we experienced once every 20 days. Our average morning commute times this week were lower than the longest ones last year.

The evening commutes

For the evening commute graph:

  • The solid black line is our average weekday evening commute in the regular lanes in October 2014. 
  • The black dashed line represents the type of commute we experienced once out of every 20 days in October 2014. 
  • The green line and orange lines are Monday and Tuesday evenings commutes in the regular lanes, respectively.

The travel time of approximately 41 minutes each evening is right in line with our average commute times in the regular lanes last year. They are well below the high commutes we experienced one in every 20 days.

The I-5 diversion myth

We’ve heard a few things about the express toll lane system and how it’s affecting traffic on I-5. One persistent claim is that more drivers have diverted to I-5 in order to avoid the tolls and perceived congestion. The numbers show us that’s not the case. The traffic volumes have remained fairly steady on I-5 since tolling began.

Know before you go: familiarize yourself with the lanes

We know that change can be uncomfortable at times. Drivers can familiarize themselves with the express toll lanes beforehand by checking the top ten things you need to know about them.

There’s also this really helpful interactive map to help drivers figure out where they should enter and exit the toll lanes.

Early days

We’re still at the beginning of a learning curve. Everyday we’ve noticed that more drivers are using the express toll lanes. Other states that have instituted express toll lanes advise it takes six months to a year before traffic stabilizes into a new normal.

We’ll keep watching traffic closely, monitoring travel times and making adjustments as needed in order ensure we provide drivers with the choice of a reliable and predictable trip on I-405.


Commuter said...

1. Open lanes to all traffic between hours of 7 pm and 5 am as previously for HOV lanes
2. Open one of the two lanes to all traffic at certain hours of the day, when traffic is building.
Two toll lanes reserved 24 hours for toll payers is excessive- and not necessary- and reinforces a growing economic gap in our culture. The loss of a non-toll lane does fall fully on the shoulders of those who do not have the ability to pay tolls.

Phil said...

Can you add today's data to the graph when you get a chance? Judging by the WSDOT Travel times website as well as the WSDOT traffic data flow map, this could be the best Thursday since around 2010.

The travel time right now from Lynnwood to Bellevue is 12 minutes below average. And, it's THURSDAY! Thursday is easily the worst day of the week to commute. Monday and Tuesday this week were bound to be bad, but Wednesday shows improvement and now with today's data, it looks like this wasn't such a bad idea after all :).

Thanks for your work.

Phil said...
This comment has been removed by the author.
Hotmamasdad said...

What we are seeing is the obvious advantage of adding capacity to I-405. WSDOT DID add significant pavement to get to 5 lanes the full length between NE 6th and 160th. WSDOT DID resolve a major weave problem at Northbound 160th/SR 522. That added significant capacity, a good thing. Unfortunately, WSDOT 'stole' an existing general purpose lane in several locations to achieve the two full lanes for the Managed Lane experiment (e.g., Northbound south of NE 70th, Northbound between 85th and 124th, Southbound south of 116th - these all had 4 GP lanes - three thru and one auxillary - prior to the HOT lane opening. Now there are only 3 GP lanes in those locations. Too bad we don't have the ability to fully use the added capacity provided by the $330,000,000 (that's $1/3 billion!) spent to provide this two year experiment.

Craig Stone reported that Tuesdays data shows in the range of 10 k trips in the two HOT lanes and 60 k trips in the three GP lanes (one direction). Let's see; that's 14% of the trips in 40 % of the lanes, and 86% of the trips in the other 3 lanes.

Adding capacity works. Managing it for political purposes is shameful.

Joel Tipke said...

Unless this is repeatable over several weeks this data means almost NOTHING! It's too small of a sample to account for variation. I've worked on teams that perform data analysis and there is very little actual, usable data here. Frankly I would be laughed out of the room for proposing such a ridiculously flimsy assumption.

Lets Do it Right said...

Shameful indeed

Lets Do it Right said...

This is exactly how I feel.

Alyssa James said...


Where'd this data come from? If you're using a accurate data set, you certainly are filtering in some very creative ways.

How much has the population grown in the past year? With no real alternate routes to take from NE to SE Seattle - the volume would naturally grow with the population. To say that the travel time has gone down in spite of removing normal lanes of traffic is WSDOT trying to save face.

I have traveled this route every day for the past year, and I can say with certainty that my morning commute has increased ~10 minutes to 30 minutes total (bc now I have to leave earlier to arrive on time) and my afternoon commute has increased ~20 minutes to 1 hour.

WSDOT said...

Hello Joel Tipke:
We understand that this is limited data, as the lanes have only been open since Sunday. With additional time, we will be able to provide data that is more robust and will be able to show trends that we are seeing. Until then, we wanted to share the data we are seeing as we want to keep the public as informed as possible. Thanks for your comment!

WSDOT said...

Hello Alyssa James:
Thanks for your comment. All of our traffic data is collected from the roadway using traffic loops that are embedded in the roadway, as they are in all our highways.

Unknown said...

Hello WSDOT! I cannot help but notice that you are comparing travel times today, post construction, to travel times during October 2014, a time when I-405 traffic was heavily impacted by the construction in progress to support the recent opening of the HOT lanes. Can you please publish a graph similar to the above, only comparing the new travel times to the travel times prior to the start of construction?

Concernd in Kirkland said...

The statistics are meaningless unless you take into account the impact to ALL the other streets between I405 and I5 north of 520. There have been dramatic increases in traffic on all of the connecting roads in the area. All my family members commutes have increased across the board 10-15 minutes. Without comment on the impact to the following streets (including Hwy522 and Hwy104 which you should have info on) the post is a meaningless puff piece. the following connector streets have been HEAVILIY impacted by the switch to 3+ HOV on I405 based upon our attempts to commute on these road both before and after the toll/HOV3+ lanes:
Juanita Drive from Kirkland to Kenmore,
100th Ave NE from Kirkland to Bothell,
Hwy 522/Lake City Way,
228th St SW from Bothell/Canyon Park,
Highway 104 from Lake City to Mountlake Terrace,
61st Place NE,
Locust Way,
Lockwood Rd,
55th Ave NE
Brier Rd

Anandakos said...


You're conflating vehicle trips with person trips. Your math is correct if you assume that the vehicles using I-405 were headed to desks and other workplaces in and around Bellevue each morning. But of course it wasn't they who were headed to those worstations, it was the people riding in them.

While of course some of the private cars in the HOT lanes are paying tolls, there are private vehicles with three or more passengers and all the buses which are not. But the total number of people in the three-plus HOV's and the buses add up to many more people per free vehicle in the lanes. Without an accurate census of the ridership on the buses and in three-plus cars, it's not at this time possible to compute an exact number.

However, a rough swag goes something like this. There are seven ST Express buses southbound from Snohomish County to Bellevue in the 7:00 to 8:00 hour. There are two Metro 342's from Shoreline and two 237's from Woodinville. That totals 11 buses southbound in that hour. Most of those eleven buses -- say eight -- are "articulated's" which hold about 60 riders. Let's assume they're 85% full, a target that Metro and ST like to meet in the peak hours. That's 51 people per hour times say eight buses is 408 and the 40-footers would be carrying three times 34 people or 102. That's a total of 510 people in buses. Multiply that times two for the "entire" morning peak -- the peak period lasts longer than that but extra buses really only run for about two hours in the morning -- and you have 1000 people on the twenty-two transit vehicles.

Subtracting those twenty-two vehicles from the figure of 10,000 vehicle trips in the ET lanes leaves ..... 10,000 vehicle trips because it's an estimate to two significant digits like 60,000 in the GP lanes.

Let's assume that 1/3 of the cars using the ET are legal HOV three's. It's unlikely to be much beyond that because it's not easy to get a carpool together from the sprawling suburbs. Those three thousand trips are carrying 9,000 people. And the other 2/3 of private cars paying the toll are probably all carrying one person, so let's say they have 7,000. Since there are doubtless some two-person trips who don't want to pay the toll in the GP lanes, the ACO out there is a bit higher that 1.0, so let's "credit" those 60,000 vehicle trips with 65,000 person trips. So the total person trips in the ET lanes is 17,000 out of around 82,000, or about 21%, half again as large as your slanted "computations".

Now I personally believe that WSDOT made a mistake in opening the system before the Bus Rapid Transit service planned by Sound Transit opens. Right now if even 1/10th of the 65,000 people using the GP lanes wanted to switch to transit they could not do so. There are not nearly enough bus trips to carry them. But once the BRT starts running there will more and more reliable service provided. That should give a significant portion of people a decent option to driving.

Tom Shore said...

Please include traffic volume compared from 2014 to 2015. I take an alternate North South connector to stay away from I-405 and my commute time had DOUBLED since the implementation of tolls on I-405.

WSDOT said...

Hello Tom Shore:
Yesterday we posted the latest data that is available for the I-405 express toll lanes. Check it out here!

WSDOT said...

Hello Commuter:
Thank you for brining your suggestions to our attention. Just to clarify, the I-405 ETLs added a lane and converted the existing HOV lane to an express toll lane. The construction project did not need to remove any general purpose lanes, but rather added one ETL lane. Currently two of five lanes are tolled between Bellevue and Bothell.
Regarding your concerns about the carpool policy, before the I-405 Express Toll Lanes launched, the 2+ HOV lanes were failing 200 days a year. The goal of the new ETLs is to keep traffic flowing in the ETLs at a speed of at least 45 miles per hour, giving drivers an option for a reliable trip if they need it. The 3+ carpool policy at peak periods will keep cars moving at 45 mph or faster, either by meeting the carpool capacity or paying the toll. But for most of the week, the express toll lanes will still operate as 2+ carpool lanes. Carpoolers will only need 3 or more passengers during the peak periods (weekdays from 5 a.m. to 9 a.m. and 3 p.m. to 7 p.m.) to qualify for a toll-free trip. At all other times, cars only need two passengers and the Flex Pass to ride for free. This policy ensures that at least two of the five lanes in both directions moves quickly and reliably through the I-405 corridor.

For more information about the 3+/2+ carpool policy decision and the extensive research behind it, you can look at the I-405/SR 167 Corridor tolling studies and reports as well as learn more about the Washington State Transportation Commission Rate Setting process. Luckily, by diverting drivers who meet the carpool occupancy requirements or who are willing to pay the toll into the ETLs, that frees up space in the general purpose lanes for those who prefer to not or cannot use the ETLs.

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