Thursday, December 29, 2022

Cold, snow and ice aren't very nice for the I-5 express lanes

By Sean Quinn

Winter weather, with its bitterly cold temperatures, snowy skies and icy roads, is both a blessing and a curse. Although it may lead to some fun snow days for the kids and cute pictures of pets, it also creates frustrating and challenging situations for both commuters and our workers alike. It leads to increased collisions and spinouts, challenges our highway maintenance teams and significantly alters travel plans. Freezing weather can also affect the Interstate 5 express lanes in Seattle, disrupting the commute in our state’s largest city.

As we saw with the deep freeze that hit our state just before Christmas, extreme winter conditions mean we have to make adjustments to the operations of the express lanes. This has been our practice for years, though it always seems to catch people by surprise. And the main question is always "Why?" Fair question. To answer, it helps to start at the beginning.

Express Lanes 101

A map of the I-5 express lanes and its on and off-ramps in Seattle.
A map of the I-5 express lanes and its on and off-ramps in Seattle

It is important to know how the express lanes function before you know how weather affects them. The I-5 express lanes are a set of reversible highway lanes that operate either northbound or southbound, changing direction based on traffic volume twice daily. They are designed to offer a faster commute option for drivers by having fewer exits/entrances compared to the mainline lanes of I-5. The lanes are operated on a typical daily schedule that allows for changes on weekends and occasionally for major scheduled events.

To complete the typical reversal process from one direction to another, it takes multiple crews.

  • Our Signals team handles the signs, the gates that close the express lanes to the direction in which they aren’t operating and a safety net that adds an extra bit of security to keep cars from entering in the wrong direction.
  • Our Incident Response Team drives up and down the lanes clearing them of vehicles and debris before the switch is made.
  • Our Transportation Management Center oversees the operation, using traffic cameras to verify that signs are correct and there is no traffic in the lanes.

During a typical weekday, the express lanes operate southbound from 5-11 a.m., northbound from 11:15 a.m.-11 p.m. and are closed to all traffic from 11 p.m.-5 a.m. On weekends, they are open southbound from 8 a.m.-1:30 p.m., northbound from 1:45-11 p.m. and closed from 11 p.m.-8 a.m.

Weather challenges

Snow and ice along the Mercer Street ramp to the I-5 express lanes.
Snow and ice along the Mercer Street ramp to the I-5 express lanes

Sometimes, because of construction, special events, or extreme weather, the schedule changes. The weather forecast plays a big role in determining whether our crews can safely reverse the express lanes and keep the roadway and ramps safe for the public.

It takes a serious weather situation to affect the express lanes. Rain is not a problem, and wind would have an effect only if it led to power outages disrupting our ability to operate the gates, signs, etc. Snow and ice, though, is a different story.

We monitor weather forecasts regularly, but there is a cutoff time hours before each switching of direction to make the call to reverse or not because of a variety of factors:

  • Traffic volume: The closer we get to when the peak afternoon commute starts, the more challenging and potentially dangerous it gets for our crews in the field to be able to safely reverse the lanes, especially in snowy/icy conditions.
  • Temperatures at the time of the reversal
  • Time to address issues that may arise during the switch

It takes about 40 minutes for the process to switch the express lanes, with a 15-minute period where no vehicles are on the road. In snowy, freezing conditions, we need vehicles on pavement to keep roads clear. Keeping traffic moving on a highway helps prevent snow and ice building up on lanes and ramps, which is especially important overnight. It can keep the lanes from freezing over, allowing our maintenance crews to more safely plow and treat the road and keep it open for the morning commute. This is one of the reasons we keep them southbound rather than northbound, as it assures lanes will be open during the busy AM into downtown Seattle.

Stay informed

A screenshot of the I-5 express lanes schedule webpage
A screenshot of the I-5 express lanes schedule webpage

We recognize the daily change of the express lanes schedule can be frustrating. We make these changes for the safety of our crews and the public and a lot of thought goes into the decision. As winter weather continues to come in waves for the next few months, we will continue to provide daily updates on the schedule. You can always find our express lanes schedule here. The schedule remains subject to change. Drivers will also be informed of any changes to the schedule in our mobile app, our Twitter account, and our real-time travel map.