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City bans dangerous right turns across Dexter bike lane at Mercer

Routing through the construction area as of late July.
Routing through the construction area as of late July.

Ever since Broad Street closed for good and Mercer changed from one-way to two-way, people biking southbound on Dexter Ave have faced a new danger: Cars making right turns in front of them to access westbound Mercer.

But the city announced recently that they are taking action by banning motor vehicles from making right turns from SB Dexter onto WB Mercer, at least during the significant reroute at the intersection in place during construction. From SDOT:

The change is being implemented to eliminate conflicts between cyclists traveling through the intersection and right turning vehicles.

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Travelers [in motor vehicles] heading south on Dexter Ave. N who wish to go westbound on Mercer St. may use eastbound Roy St. and southbound 9th Ave. N to reach westbound Mercer St.

Readers began voicing concerns about these right turns almost immediately after two-way Mercer went into effect. The Seattle Times reports that the action comes after two right hook collisions at that intersection in one day last week.

Cascade Bicycle Club was quick to praise the city’s effort to maintain safety on Dexter during the significant road changes in the so-called “Mercer Mess” area:

“We are encouraged by the Seattle Department of Transportation’s pro-active steps to safeguard the lives of Seattleites. Dexter Avenue is well known as one of the more dangerous streets in the city with many high profile collisions in recent years, including the death of Michael Wang in 2011,” said Brock Howell, Cascade’s Policy & Government Affairs Manager.

“As Dexter Avenue and Mercer Street continue to undergo significant improvements, it only makes sense to continue to evaluate and modify street design to ensure all people — whether they are driving a car, riding a bike or walking — can move safely through the corridor.”

With so much construction in the area — including big detours to make room for utility relocation work as part of the SR 99 deep bore tunnel project — travel along one of the city’s busiest bike routes has a long way to go before it is truly comfortable.

Keep letting the city (and your fellow readers in the comments below) know about your concerns as the route detours shift and change. You can contact the Mercer project team at [email protected] or by calling the 24-hour construction hotline at (206) 419-5818.

In case you’ve forgotten what all the work is even for, here’s a rendering of the future connection on Mercer from Dexter to Lower Queen Anne:


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28 responses to “City bans dangerous right turns across Dexter bike lane at Mercer”

  1. Patty Lyman

    Step by step the longest march can be won.

  2. Ben Morris

    Regarding the SDOT ‘future of Mercer’ rendering: add 50-100 more cars, then it would be an accurate illustration. ;)

    1. LWC

      I had the exact same thought. Why do these types of renderings always choose to show 6am on a Sunday in July?

    2. Heh, a huge jam of stopped cars in one direction and clear road in the other. That’s what I always see on Mercer.

  3. Peri Hartman

    This is great for cyclists but quite a burden for motorists. There is no other right turn to get to Mercer till you get to Denny – which ultimately increases traffic on a number of other streets, compounding the problem.

    An improvement, perhaps, would be to add a detour sign a block or so back, advising motorists of no right turn and marking a detour route left on the street before – Roy st. – and then making a couple rights to get on Mercer. I think a lot of drivers would appreciate this.

    Also, I wish SDOT would change the no right turn to say “except bicycles”.

  4. For the following reasons I question whether this is really any better:

    – We’re replacing right turns at Mercer with lefts at Roy; the conflict is now with people biking north, and I’m not sure it’s any less in magnitude. Maybe it’s less common for people biking northbound than southbound to be going faster than surrounding car speeds (I believe that’s a strong risk factor for collisions involving uncontrolled turns)?

    – If lots of drivers turn left at Roy southbound traffic on Dexter north of Roy will have to wait for them. This will make it even more common for people biking southbound to be going faster than car traffic at Roy (where drivers turn to the west, across the SB bike lane, to get to northbound Aurora) and at intersections and garage entrances north of there.

    – The last thing Metro route 40 needs is even more people turning onto 9th from Roy. The last thing route 8 needs is people deciding to use Denny instead of Mercer.

    This sort of reminds me of the Dick’s descending bike lane situation. SDOT recognizes a difficult problem and tacks on a solution that doesn’t really solve it, or in this case, that just changes the problem.

  5. Tristan

    I love how the S-T editor took a look at this story and decided there wasn’t enough war against cars nonsense and added it in with the “just who owns the roads anyway” line and the headline. Even the driver they got doesnt seem to be that annoyed and likes bike infrastructure

    1. “Who owns the roads” is actually a good point. As Seattle taxpayers, cyclists own the roads just as much as everyone else and have just as much right to decide what happens on them. Not that you’ll see recognition of that in the ST.

  6. Andy

    I sometimes wonder if things wouldn’t be better off for everyone if they just closed Dexter to cars between Mercer and Denny while this construction is ongoing. I can’t imagine anyone driving is aware of how bad that intersection is and still decides to choose that route.
    Leave Dexter open to buses and bikes, but shorten light cycles and sync them better to the cycles on Mercer (when Mercer traffic has a green light but is so backed up it isn’t moving anyway).

    1. I agree. I find that intersection confusing as a driver. Actually, I hate driving westbound through SLU at all because the road patterns change so often and it’s hard to anticipate what is coming up.

    2. Peri Hartman

      That’s an interesting idea. Since Westlake is already a major corridor (and SDOT wants it to be that way), why does Dexter have to also be a major motor vehicle corridor?

      And the Dexter & Mercer intersection is causing backups all the way to the other side of Uptown. That may diminish when SDOT gets 3 lanes going through but having less traffic on Dexter might help, too. (Of course, that traffic would shift to Westalke so I don’t know if it would help the big picture.)

      1. Andy

        I think in addition to Westlake, it might divert traffic to Aurora. Right now, in the AM peak, if you’re heading to downtown, it is probably *almost* faster to backtrack on Dexter to 6th, and get on to SB Aurora via Raye. Closing Dexter between Mercer and Denny and posting appropriate detour signage could divert those drivers without making a different Mercer intersection worse.
        Doesn’t do anything for the drivers on Dexter heading to SLU, but they’re a lost cause if they haven’t realized that Westlake is vastly superior to Dexter in the AM.

  7. […] Seattle Bike Blog says that anyone with a suggestion or observation about the Mercer – Dexter intersection […]

  8. JesseMT

    New-ish cyclist here, wondering the best way to get to and through SLU from Fremont and points north. A few times I’ve tried the Westlake/parking lot route, but get confused by lack of signage when I get to Lake Union Park. I see some bikers joining traffic and the streetcar tracks on Westlake. Some wait for the light and cut over to 9th. None of these look optimal. The reason I haven’t taken Dexter is that the idea of a left turn from the southbound bike lane on Dexter, across northbound traffic into the construction zone near Amazon, seems terrifying. Thanks for any suggestions!

    Huge fan of Seattle Bike Blog by the way. Great educational tool for me to get up to speed on city bike policy and best practices. Thanks to Tom and all the great commenters.

    1. Peri Hartman

      As for the Westlake part, there’s a big effort underway to add protected bike lanes. See the project details at


      If you can spend a bit of time to help support the project, check here:
      in particular, the “volunteer” link.

    2. I’m not sure exactly where you’re trying to go in SLU, but if you don’t want to make a vehicular-style left from Dexter you can instead make a two-stage left at the light at Harrison.

      To make a two-stage left, proceed into the intersection with the green light in your original direction, then pull off to the right of bike lane flow (around the front edge of the crosswalk) and stop in front of the lane you want to turn into. Then when the light turns green in the direction you want to go, go in that direction.

      Another option might be to approach on Dexter, then take crosswalks and sidewalks on Mercer to 8th Ave N, and roll down 8th toward your destination.

    3. Lisa

      That entire area is a hot mess right now- I actually think Harrison is closed east of Dexter, so you might not be able to turn there. I usually wait for the light at the end of the Westlake parking lot and continue south on 9th, only once you get past Mercer the bike lane disappears because of construction… if I’m feeling lazy (not wanting to keep up with traffic) I just use the sidewalk.

    4. Andy

      I’m not sure if this will apply to you, but for any speed at or above 15mph, personally I prefer to take the right lane on Westlake southbound in the AM. Traffic is light enough on Westlake that entirely taking the right lane doesn’t materially slow down automobile traffic flow – the only thing time it’s annoying is if there’s a bus (I’ll typically let it pass and then just stay behind in lane when it stops instead of playing leapfrog).
      I find this to be more comfortable than riding in the Westlake parking lot, both because I’m terrified of pre-coffee accidents and because it let’s you turn directly and easily on to 9th, which is then quite comfortable.
      Depends on where you want to go in SLU from there, but I find that route to be the best compromise of comfort and safety, personally.

      1. Peri Hartman

        You probably want to wear a string of holiday lights, too. Even if the traffic is light, the difference between being hit in the parking lot and at 40+ mph on Westlake is ending up in the hospital versus the morgue.

  9. Hutch

    I applaud the effort to limit collisions, but I’m sort of confused by the implications of this and where the city sees the traffic going. My fiance works in Seattle Center and primarily uses Dexter to bike commute south. Does the city expect bikers to head all the way down to Denny and take a right turn and intermingle with traffic, passing three or four other right turns before heading up 5th or Broad? Right now it makes more sense to use the pedestrian paths westbound on Mercer, although that’s also not ideal, obviously.

    1. People biking are still allowed to turn onto Mercer.

      1. Hutch

        The signage at the intersection doesn’t indicate this, from what I saw.

      2. Breadbaker

        The signage makes no distinction between bikes and cars for turning right onto Mercer. But given there was exactly no traffic heading westbound on Mercer at 2:30 this afternoon and it was backed up to forever eastbound, I doubt anyone would do anything about a bike turning. My guess is Al is right, but the signs aren’t.

      3. Josh

        In the street, bicycles are bound by the same laws as cars, so bicycles are currently banned from making right turns at this intersection. SDOT might not have intended that, but if it’s just a “no right turns” sign, it applies to bicycles. SDOT does have “except bicycles” supplemental plaques, they’ve used them elsewhere.

        As a practical matter, I doubt there’s any enforcement risk to cyclists, but if you happen to get in an accident while making that right turn, your illegal maneuver could be used against you.

      4. I will buy the claim that it would be technically illegal (the best kind of illegal!) to turn into the general traffic lane of Mercer on a bike. But onto the far sidewalk, which is the officially supported route to cross under Aurora? I don’t think so.

      5. RKT

        Yesterday afternoon there was a uniformed officer standing on the NW corner of intersection. I suspect they wanted a physical presence to try to increase compliance.

      6. Peri Hartman

        Tom, can you get a clarification from the city as to whether cyclists are allowed to turn right at this spot – and maybe get them to change the signage?

        If not permitted, to go right I’ll have to make a left in the crosswalk, get in front of the waiting cars westbound mercer, and then go west. Kind of crazy.

  10. Bud

    This is nice, but NO ONE pays any attention to the “NO RIGHT TURNS” sign. No one at all, they still turn, just quicker now that it’s illegal. I see it every single day, even city trucks.

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