Originally Posted by Brian Ratliff
HH, in my experience, the "conspicuity curve" flattens out after you get to the left edge of the bike lane. From there to the center of the lane, there difference in "conspicuity" is neglegible.
FWIW, from these words I pictured the graph that you posted later. But thanks anyway... Good job on the written and graphical descriptions. You've made yourself very clear.
I am curious though if you're talking about conspicuity primarily to overtaking traffic (and potential right-hookers), or if you're also thinking about your conspicuity to cross traffic when you draw this graph?
With respect to conspicuity to the rear, I don't much disagree with you, except in the case of when approaching an intersection I find moving out of the bike lane to be very helpful in terms of coaxing right turners behind me to slow down and get behind me rather than pass and hook right. I observe other cyclists get jammed up in the (dashed stripe at this point) bike lane all the time.
Now, on a street with no same direction traffic and driveways and alleys, I find that being several feet left of the bike lane stripe makes me MUCH more conspicuous to anyone who might be moving into or across the road from the side than riding even near the stripe of the bike lane, much less in the center where your right shoulder is only about 18 inches from the curb in a 5' bike lane. There is just no comparison. For conspicuity to cross traffic, I'd say the conspicuity line on the graph remains low and flat from the curb to about the BL stripe, then a steep climb until you're about to the right tire track, and then begins to climb less steeply for a couple of feet, finally flattening at high conspicuity around the point between the left and right tracks, perhaps a foot or two to the right of that.
Originally Posted by noisebeam
This points out what I don't like about the BL stripe. I often find the ideal place to ride a roadway is where the stripe is placed, but as soon as it is there, it becomes a 'no ride' zone to avoid riding in an ambigous lane position. Many drivers follow their rule of as long as I am not in the BL I can ignore passing cyclist, which leads to getting lots of close passes when riding left biased in a BL.
My experience is similar, though I have a different explanation for why this occurs. It goes back to the "symmetrical" theory. The idea is that when a driver approaches a cyclist from behind, the subconscious assumption is that the cyclist needs about as much room to his left as he has left for himself on the right.
Anyone who has a mirror can discover this very quickly. That's the general rule (there are exceptions, of course). How it applies when riding to the left of the bike lane stripe is that the space estimate does not include the space demarcated by the bike lane stripe! Remember, most motorists treat the BL stripe like a shoulder stripe - to them, conceptually, it's the edge of the road. If you're riding in the bike lane, you're off the road from their perspective. If you're riding a few inches to the left of the stripe, then the space you're leaving yourself is a few inches on the right, and that's all they feel obligated to leave on your left. If the stripe is removed (assuming WOL = NOL + BL for the moment) then suddenly you're 5+ feet from the edge of the road, and they are more likely to respect about that much space on your left, which you may quickly discover is more than enough, and move further right. This is why many vehicular cyclists claim that a BL stripe often causes them to ride further left.
By the way, the major exception to the symmetry rule is when you leave just enough room for them to squeeze into the lane on your left. If that's the only way they can fit into the lane, sometimes they feel justified in encroaching on that space that they would normally respect. This is especially true when you are where you are in order to stay outside of the door zone. So on a street with curb parking, often your choices are:
- ride in the door zone (no thanks)
- ride just outside of the door zone (but this leaves just enough room for motorists to squeeze into the lane to your left, passing you to closely)
- ride even further left, forcing motorists to have to change lanes to pass you (expect honking, since avoiding the door zone is not understood, so you appear to be taking the lane for no reason).
No good choices!
Originally Posted by Brian Ratliff
I firmly believe that a NOL+BL is not simply a WOL+stripe.
It depends. A 10' NOL + 5' BL = 15' WOL. It's basic math. Now a standard 12' lane adjacent to 5' BL is more like 17' lane, or a VWOL (Very WOL). As far as widths/lane types go, off the top of my head:
9-10' = narrow (only shareable at crawling speeds, if that)
11-13 = standard (many of which arguably too narrow to be safely shared in many circumstances)
14+ wide (usually wide enough to be safely shared)
Your experience confirms that.
I think Al's experience is more likely to be evidence of the validity of my theory about the BL stripe being treated as a road edge marking, and thus only respect as much space to the left of the cyclist as he has between him and the BL stripe "road edge" on the right.
A simple way which might eliminate this concern about visual clutter is to place a shoulder to the right of the bike lane.
Your "visual clutter" speculation aside, this statement cracks me up. Yes, it's very simple to find 2-3 feet to the right of 10s of thousands of miles of bike lanes to create a shoulder to reduce the "visual clutter" that makes us difficult to see. Let's just cut into the sidewalks, which we can move further right as well, into people's front yards and storefronts!