They did the thing I suggested at 9th and Mercer, and it almost works!
They did it! The Seattle Department of Transportation changed the order of the traffic signals at 9th Ave N and Mercer Street to allow straight traffic, the bike lane and the crosswalk to go before the left turns. This was an idea I first suggested more than six years ago shortly after the new Mercer Street configuration opened. I then made a longer video and post about the idea in April 2022 when I was biking through there every day while doing preschool transportation. Every single time my kid and I tried to get through here heading northbound during the early evening commute, left-turning traffic from southbound 9th Ave would block the bike lane and crosswalk.
I am barely exaggerating when I say every time." It was a very uncomfortable and potentially dangerous situation. One of the most common reader complaints I get from folks via social media or email are about this intersection. It is very well-used, providing the most popular connection between the city center and bike routes to most points north. There are no easy solutions to backed-up traffic on Mercer Street since those are caused by traffic getting onto I-5, but surely the city could at least do something to keep the bike and crosswalk open, right?
I am not a signals engineer, but I thought I had a simple fix: Just change the order of the lights. And after more than half a decade, they did it. And the results are...I think pretty good but not perfect!
I do not have hard data, but I do have footage from before and after since I stood out there for about an hour in 2022 when making my first video. The new signal order does work how I hoped it would, keeping the bike lane and crosswalk clear much more often than before. However, it's not completely fixed. People on Mercer still often block the box by pulling forward before there is space for their vehicles on the other side. It does not happen as often as before, but it does still happen. I also suspect that the timeframe for blockages is shorter now. I saw almost no blockages until a little after 4 when traffic levels begin to peak. Before, the blocking seemed to begin as soon as traffic was even a little heavy. There were also signal cycles around 4:30 that were fully clear, something that almost never happened before. But keeping people safe and providing an accessible street crossing more of the time still isn't good enough.
Watching the intersection also highlighted the other inherent safety problems at this intersection as well as many others on Mercer Street. The corner turn radii are so wide that right-turning cars are extra problematic. I saw a lot of near misses, especially between right-turners and people using the crosswalk. People driving can turn quickly into any one of three lanes, and the crosswalk users must travel a surprisingly long distance across all these lanes, leaving them exposed. The city should consider either banning right turns entirely or constructing a physical curb extension or bike lane protection island of some kind so that people turning must make slower and more careful turns. The current design does not work and is not safe. You don't need to stand out there for very long before you witness a scary interaction. The issue is not that a few people are behaving badly (though some certainly do), it's a design problem.
Have you noticed an improvement in this intersection recently? Let us know in the comments below.