How much time you save for each dollar spent in the I-405 express toll lanesBy Ethan Bergerson
Everyday, more than 51,000 drivers choose to use the I-405 express toll lanes. Drivers tell us they like having the choice for a faster trip when they really need it but sometimes it's hard to tell exactly how much time you're saving because toll rates change in confusing ways.
Why do toll rates change?
Toll rates manage traffic in the express toll lanes based on real-time traffic conditions. Every five minutes, the traffic management computer system updates toll rates based on how many cars are in the express toll lanes and how fast they are going. The goal is to use the laws of supply and demand to keep traffic moving.
When traffic is flowing smoothly and there is plenty of room in the express toll lanes, the price is low. When the lanes start to fill up and slow down, the price goes up in order to discourage too many cars from getting in so that traffic in the lanes can keep flowing smoothly.
Tolls can reach $10 when congestion is heavy. For most people, $10 is only worth it when you're in a rush to something really important but is too much to spend every day. We understand that, and that's what makes it all work. When traffic is at its worst, higher tolls help traffic so that these lanes can move as many people as possible without jamming up. That's how we make sure that you have a dependable way out of traffic when you really need it.
Time is money, so exactly how much time do you save when you pay to use the express toll lanes? Do you get a deal when the tolls are high or low?
We crunched the numbers and it turns out the more you pay, the more time you will probably save. When tolls are at $1 drivers save an average of 5 minutes compared to the regular lanes on trips between Bellevue and Lynnwood. Time savings add up pretty consistently when toll rates go up, and for every dollar the toll rate increases drivers save about another minute and a half. When tolls are at $10, drivers save about 20 minutes on average.
The average toll people are paying during peak periods is $3.29. Drivers are saving an average of 11 minutes heading south in the mornings, and 14 minutes heading north in the afternoons.
Sometimes there are slow spots but you can save a lot of time overall on the full trip. To do this math, we looked at how much time drivers saved for a trip all the way between Bellevue and Lynnwood. We also only looked at data for the peak times of day.
The graph below shows the average minutes saved on full corridor trips during peak periods compared to the rates displayed during those trips.
How is this possible?
It is frustrating spending $10 and then hitting a slow spot in the express toll lanes. If that's happened to you, you're probably feeling a little skeptical right now. But remember, high toll rates mean that the express toll lanes have started to get crowded and we're trying to keep it under control.
On average, express toll lanes move about 19-24 miles per hour faster than the regular lanes at peak times. That doesn't mean there's never a slow spot, but overall these lanes run way more smoothly than the old HOV lanes did a few years ago.
We try to keep things moving at around 45 miles per hour, because that's the most efficient speed for moving the most cars at a time. When traffic is at its worst, each express toll lane can carry up to 30 percent more cars than a regular lane in some locations at the height of the peak commute relieving some pressure on the regular lanes. So even on the days when the toll isn't worth it to you, at least you know that it's freeing up some space in the regular lanes around you when other drivers choose to pay.