This is the Cesar Chavez "Hairball" intersection with Highway 101 in San Francisco.
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I pass through here a few times per week on my bicycle to get to Caltrain. I am not alone - on this morning's ride there were three other cyclists passing through this same spot - to get to the Caltrain station (or any other destination in that area), you either have to brave the hairball, take a "more direct route" over Potrero Hill (a hill with a 20%+ gradient) or detour a couple of miles to 17th Street.
On the right side of the photo you can see a sidewalk along the freeway onramp. This leads to the "Underpass of Broken Bottles and Dreams", a sidewalk cum bike path that requires you to first access it by crossing the onramp, then follow a narrow chute under the 101, strewn with well, broken bottles and dreams (a.k.a. homeless people). There is a signalized crossing of Bayshore Blvd and then you rejoin Cesar Chavez in the offramp from 101-N. Two of my companions chose this option this morning.
Another woman chose against the path. She rode "as right as practicable" so to speak, in the far right of the roadway, then crossing the freeway onramp and then hugging the white line on the right of the underpass. This required her to pass the exit onramp to Bayshore Blvd South, then go under the freeway.
I chose a third option. Having turned onto Chavez via a left turn off of Bryant South, I took the middle of the far left lane. A maneuver that requires nerves of steel and hopefully cooperation from drivers as you navigate under the underpass. The majority of traffic is headed to the freeway or Bayshore so I find this to be the spot that gives me the most breathing room. After getting past the Bayshore onramp, I switch into the right hand lane to finish the underpass.
This led to quite a scene - there were cars headed to the freeway, cars headed to Bayshore, and a car headed through, with a bike in the left lane and a bike hugging the curb in the right lane. Fortunately we all sort of looked out for each other and made it through, but I won't call it comfortable nor efficient. When my female companion and I finished our crossing, we then had to merge across the 101-N offramp that enters Chavez, which was a bit messed up because there were 2 cyclists merging from left to right, and 2 cyclists on the right hand side who had just crossed the onramp having come off the "UBBD".
How it this optimal? Safe? Useful? Answer - it's not. You can't really say that any of us broke the rules, but we all took a different choice from three unpalatable options. Designing useful and clearly defined infrastructure that works for bikes and cars is good for everyone.
And of course, when we reached Pennsylvania Avenue, where I turn left to go to Caltrain, one of the bike path cyclists took the same left turn as me, onto a three lane section, the rightmost lane being the onramp onto 280-N. I took the middle lane (rightmost non-freeway lane), he took the left lane (avoiding the 280 traffic and traffic from Chavez WB that has a free right turn into the freeway onramp and often merges into the middle lane). Needless to say that didn't work out too nicely either. The other two intrepid cyclists bypassed Pennsylvania and took a left onto Iowa Street instead, which has its own issues.
This is what happens when your designs do not take into account the mix of traffic that will use a street.