I-5 Lane Closures: Worst Travel Times and Routes

Traffic Challenges on I-5 and Alternative Routes

The initial week of lane closures on northbound I-5 has been a tough experience for commuters, but there have been some signs of improvement. On Monday, the situation was particularly challenging as many drivers left early, leading to a concentrated rush that made traffic even worse than expected. According to RB McKeon, a Public Information Officer with the Washington Department of Transportation’s Northwest region, this synchronized departure created a bottleneck that wasn’t ideal.

However, by Tuesday morning, conditions began to improve, and Wednesday saw further relief. Despite these improvements, travel speeds remain slower, and journey times are longer, according to Bob Pishue, a transportation analyst for Inrix. The data reflects how people are avoiding I-5, causing congestion on alternative routes.

Impact on Key Routes

On I-5, southbound traffic from 7 a.m. to 10 a.m. is moving 35% slower than last week. This slowdown continues into the 11 a.m. to 2 p.m. timeframe, where speeds are 32% lower. While evening southbound traffic moves faster, northbound speeds drop significantly, being 29% slower than last week.

SR 99 has become one of the most used detour routes. Southbound morning traffic is 36% slower compared to last week, and midday traffic is 32% slower. In the evening, Northbound traffic is 29% slower.

15th Avenue NW, which serves as a major route to Downtown Seattle, is also experiencing significant delays. Morning southbound traffic is 14% slower than last week, while evening traffic is 4% slower. Although midday traffic remains comparable to previous weeks, the overall impact is noticeable.

I-405, another alternative route, sees Southbound traffic slowing down by 2% in the morning and 20% in midday. Northbound traffic picks up in the evening, but it is still 19% slower than usual.

25th and Montlake avenues are also affected. These roads, not designed for highway traffic, are seeing increased congestion. Southbound traffic is 17% slower in the morning, rising to 19% slower in the middle of the day. Evening Northbound traffic is 14% slower.

Earlier Rush Hour and Commuter Adjustments

Pishue notes that rush-hour traffic is starting an hour earlier, especially on I-5. Data shows that on Monday and Tuesday, speeds began to drop around 5 a.m. By 6 a.m., speeds were below 40 miles per hour. Congestion sets in around 7 a.m., and southbound travel speeds don’t return to normal until after 4 p.m., when Northbound traffic increases.

Compared to I-5, SR 99 sees a quicker recovery, with southbound speeds returning to normal around 11 a.m. Sound Transit reports higher ridership this week as lane closures began. Parking lots and garages in northern communities, which have been filling up regularly since 2024, are now filling up an hour earlier, before 8 a.m.

David Jackson, a Public Information Officer with Sound Transit, advises commuters to plan ahead if they want a parking spot. “If you’re wanting to snag a parking spot, you’re going to have to be an early bird to get that worm,” he said. He also encourages using transit options.

Tips for Planning Your Route

There are several ways to plan your commute via transit in King and Snohomish Counties:

• Sound Transit
• King County trip planning
• Community Transit

McKeon acknowledges that not everyone can adjust their schedule, but she urges those who can to consider traveling outside peak hours. “If you have that flexibility, please do consider how you can help the system. We really do think that we’re all in this together and we’ll get through it together,” she said.