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More mixing zones :(

Seriously, why does is take a decade for new designs to be incorporated? Protected intersections NOW!!

Also, is Clarendon Blvd slated to get a protected lane? Or are cyclists expected to only bike in one direction?

Looks like the same turn infrastructure that doesn't work on L NW.

Maybe because Wilson is uphill and Clarendon is downhill? Cycling uphill you are going much slower than traffic, but cycling downhill you can travel at or near traffic speeds. I have to say, knowing that hill, I don't want to bike down it between parked cars and the curb (the mixing zone jeffb mentioned). You are either going too fast to avoid people walking across without looking, or you're slowing down far more than I want to. I'd probably end up taking the lane. Going up hill, I don't mind being in a mixing zone too much.

Huge step for Arlington. I applaud their attempt at protected bike lanes! Is this the first? Unfortunately, it's 10 blocks, with mixing zones for turning.

NACTO standards, which likely are just a Sky Mall book for a select few engineers due to limitations on design placed by Arlington leaders, would dictate something altogether different: physical separation throughout, and protected intersections.

It's a step in the right direction, but bikable Arlington is far off in the future for the 8-80 year olds.

To what extent do we know that the mixing zones are a problem? My experience on L and M is that they aren't, but I'm usually there when traffic is light. Is there any data or studies on it?

Also, I'm not seeing the protected intersection in the NACTO guidance? Maybe that's the problem?


I ride on L and M during rush hour and find L to be worse, but not sure if due to higher number of turning vehicles or design---I rarely experience drivers turning on M, so maybe not enough samples to have bad experiences.

In contrast on L, the problems include:
- Drivers making a left turn from the second left-most lane (i.e., the first through-lane outside the mixing zone). There are no street markings or signs prohibiting this---there need to be + camera enforcement as this is the most dangerous and least predictable.
- Once in the intersection, drivers coming from the mixing zone usually veer right to make a wider left turn, reducing the space for bikers between turning and through cars
- Drivers swerving into the mixing zone without signaling (often) or even looking
- Drivers straddling the bike lane in the mixing zone while waiting at red signal
- Drivers blocking the entrance to the mixing zone when car portion of the zone is full of other drivers waiting at red signal

One or more of these happens to me every day.

As far as solutions, I would suggest:
- Signage and camera enforcement preventing double-turns (i.e., turns from second left-most lane)
- Zebras, small bumps, or other mechanism in addition to paint to separate bike lane in mixing zone and intersection from through and turning cars
- Camera enforcement of blocking bike lane at entrance to mixing zone.

xmal pretty much covers my objections with mixing zones.

One thing I'll add is that US protected bike lane design continues to fail "the 10 year old" test. That is - is such design really safe and usable for a school age child?

I know many argue that a glass half full is better than none. But designers, all too often, will go with the path of least resistance and rather than advocate for the best design will fall back upon existing precedent.

Also often called the 8-80 yo design. Would you want your next of kin in that age range to ride x design?

Good question. Here's the design by Nick Falbo who has designed a few places in Portland. DDOT and Arlington appear to be at least 30 years behind the California criteria referenced in the doc (although I don't think they use them there either).


"International Precedent" seems to be the case for protected intersections.


Am I the only one who finds these markings hopelessly confusing and impossible to decode upon first viewing (likely at 20-25 mph)?

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