Originally Posted by
Helmet Head
I think the white bike lane or shoulder stripe makes it more likely that the motorist won't be paying any attention to what is in the space to the right of the stripe as compared to the attention he might give it if the stripe is not there.
I don't believe the stripe lures motorists. When there is no cyclist in the road and the shoulder is empty, then I believe the motorist is just as likely to drift into the shoulder, whether it is demarcated with a stripe or not. In that sense, the stripe makes no difference.
But, here's the key. If a cyclist is in the shoulder, then I do believe whether the cyclist is noticed is a significant factor in whether the motorist drifts into the shoulder. In particular, if he notices the cyclist, then he is much less likely to choose to pay attention to something else, and drift because he is distracted.
Combine that with the higher probability that a cyclist will be overlooked if he is riding in space separated by a stripe, and you have a higher probability that a cyclist in a marked shoulder (or bike lane) will be inadvertently drifted into than a cyclist riding in a shoulder that is not demarcated with a stripe.
So how does one demonstrate whether this is true or not?
If I'm further left, motorists will react earlier to my presence, often slowing down and moving over earlier compared to when I'm further right. I feel that this observed driver behavior justifies me riding further left in certain circumstances.
But all this doesn't necessarily mean that I am noticed sooner by being further left. It could be that cyclists in both positions are noticed at the same time, but the motorist seeing the cyclist further left instantly knows that he has to slow down or make a lateral movement, while the motorist seeing the cyclist further right has a little delay time because he's trying to figure out whether or not he should keep the same course.