By Emily Pace
It’s been just over three weeks since the Interstate 405 express toll lanes opened, and we want to take a look back at what we’ve been seeing. As a reminder, it takes time for any big project to get up to full speed and we still expect it will take traffic six months to a year to reach full efficiency as drivers continue to adjust to the I-405 express toll lanes.
Express toll lanes moving more people faster
The express toll lanes have been helping move more people and vehicles quickly through the corridor than the old HOV lanes.
Average speeds and travel times between Bellevue and Lynnwood in the express toll lanes maintained near free flow conditions during peak periods again during weeks 2 and 3. The number of vehicles in the express toll lanes has surpassed the previous HOV levels throughout the two express toll lane sections, and are nearly double the previous HOV volumes during the highest peak hours towards the center of the corridor such as near Kirkland and Kingsgate.
So why did the express toll lanes sometimes look empty? Because the express toll lanes manage traffic more efficiently allowing more vehicles to travel the same distance in less time without getting stuck in traffic.
Changes in the regular lanes
After our first week, we reported that regular lane travel times have improved slightly since the express toll lanes have opened even though more cars are on the road then this time last year. Since then, we’ve continued to see these commute time benefits for those driving the entire distance between Lynnwood and Bellevue, but we’ve also noticed shifts in the times and locations of congestion that help explain why some drivers are telling us that they are seeing congestion where there was none before.
Travel time improvements for the whole 17 mile trip
The 17 mile trip from Lynnwood to Bellevue improved in the regular lanes during the morning commute. The above graph shows that the peak morning commute time was nearly 15 minutes shorter every day last week than the average weekday morning commute in October 2014.
The northbound evening commute gained some improvements in the regular lanes during the evening commute. Commute times showed improvements last Monday, and Friday compared to October 2014, but with increased congestion at times on Tuesday, Wednesday and Thursday. All days were within the 95th percentile of traffic from this month last year.
Shifting congestion points
While we’re seeing less congestion overall, we are seeing some congestion points shift. It will take traffic six months to a year to fully adjust and settle into a new normal. It’s too soon to draw long-term conclusions. We anticipate congestion points will shift and may vary day to day and month to month in the meantime. We’ll continue to share what we see.
Many drivers have commented that traffic seems to have gotten worse for their commute. For example, the new braided ramps connecting I-405 to SR 522 has helped to lessen what had been a major bottleneck on the northbound evening commute, however we've observed that some of this congestion has shifted further north along the highway.
In other words, while the trip in the regular lanes between Bellevue and Bothell has been improved, trips from Bothell to Lynnwood between Beardslee and SR 527 are seeing congestion during the evening commute. This has varied by day, with some days being the normal range we see on I-405 and other days travel times have been slower.
We've also noticed some shifts in the timing of congestion, which we are now observing earlier in the afternoons and more often on weekend commutes. Weekend congestion may be due to fewer drivers being familiar with the express toll lanes than regular commuters.
While this is a win for drivers going the entire distance along the corridor, it certainly explains the frustrations some drivers who drive a shorter portion of I-405 are experiencing.
Regional traffic patterns
We are working closely with cities and jurisdictions to monitor traffic on their roadways and do not have any conclusive data.
Regionally, we’re seeing traffic volumes rise throughout the corridor compared to this time last year, but cars do not seem to be going to I-5, I-90, or SR 522 in greater numbers than I-405. On the contrary, traffic volume has grown by less than 5 percent in all of those roads with the exception of I-405 where volumes have increased by as much as 9 percent.
In our next blog, we’ll talk about changes we made to stretches of I-405 where we converted auxiliary lanes to continuous general purpose lanes. We’ll discuss why we made those changes and how they’re impacting traffic so far.