Wednesday, April 29, 2009

Mixed Feelings in the Left Hand Tire Track

Steve A. responded to my first post, and I said I would address his comments. So here goes.

SA) I have mixed feelings about that left tire track lane position. Here's why:#1 - it tends to be smoother at the center of the lane.

CS) I'm jealous! Most of my roads are coated with Chip-Seal. After a good hot summer, the tires wear a much smoother surface. There is a particular type that Ellis county favors that fails to stick to the under-surface if not pressed down firmly by passing traffic. It becomes an extraordinarily rough surface between the tire tracks. When light permits I will take some photos.

SA)#2 - As vehicles tend to pass closer to the cyclist (on average) if one is traveling in the left tire track. This is simply due to the fact that the road is only so wide.

CH) Correct. If the motorist overtakes in the next lane. They are more prone to straddle pass (where they share part of your lane with you) when in the right tire track. Motorists have hours and hours of practical training of keeping their vehicle within a lane. I have more confidence that they will accurately judge their clearance when there is a lane marker between us!

SA)#3 - An overtaking vehicle has less total time to get back into the proper position the further it has to move left to pass.

CS) I am not really concerned about this. It is the duty of the vehicle operator to pass with due care. Besides, how hard is it to pass a bicycle anyway?

SA)#4 - If I look at the Sousa data, passing separation is best when traveling in the right tire track. That's consistent with the observation that one should position oneself so that the overtaking motorist makes a correct move with the minimum need for thought. Moving further to the left doesn't cause any added impact on the automatic motorist response.

CS) First the actual difference in the observed distance between the two lane positions is about four feet, with six to seven feet the closest pass from further out in the lane. (Note, the data is from the right tire track to the center of the lane.) There were no straddle passes observed from the most commanding positions. I am comfortable with that, but then, I was a bicycle racer in my youth. I may have a greater tolerance for objects being in close proximity than other cyclists.

Second, overtaking traffic is not my primary concern. I face much greater peril from what is ahead of me. I have better sight lines from the left side of the lane. I think I am likely to have better success at avoiding right hooks from there as well.

SA)#5 - Riding too far to the left encourages a pass on the right side of the cyclist.

CS) Yes, this behavior caught me by surprise when I first began riding exclusively in the left tire track. It is surprisingly common. I inspire such overtakes about every week. They are most common on state highways when a shoulder is present, but like you I've had a number of them off in the grass as well. One of them was on the road that is pictured on the previous post!

Curiously, they seem to give me more room on that side!

Another common objection I hear about is that such an "aggressive" lane position displays "arrogance" and is designed to annoy motor vehicle operators.

On the roads I commonly travel on, motorists cannot overtake me without encroaching the oncoming lane, so no matter what position in the lane I take, they must wait for a gap to pass me safely.

The fact that a motorist cannot reason this out and gets upset is neither my fault nor my problem. He may pass me or not as he wishes. It remains his duty to pass slower traffic in a safe manner and in due care.


  1. Bottom line is minimizing the number of dangerous situations per mile travelled. Every cyclist faces different circumstances and should evolve his/her cycling style based on those. The general "cyclists fare best" rule is a starting point. Looking at ChipSeal's post, I think we're not all that far apart.

    Personally, I've had no scary encounters with cars in the last six months. Last one before that was a blue pickup with "outlaw" on the side and that was mainly when the driver came by for a second pass. But I'm not carfree either...

  2. It is DEFINITELY smoother at the center of the lane on Westport Parkway out by Alliance Airport. Checked it out again yesterday. Those 18 wheelers seem to create a major washboard in both the RH AND LH tire tracks.

    On that road, to avoid excess wear to the bike and my fillings, I'll stick to the center of that 12 foot wide bike lane. Westbound, I'll take the Old Denton Road/Hwy 170 combo to avoid the issue altogether...

  3. It may not be your problem that the motorist gets aggravated, but it can be, at least in part, your fault. If taking the left tire track is viewed as aggressive, you have already kind of pissed off the other driver (maybe not your fault, but you're an influencing factor).

    My sense is that as long as the cars see you, you won't get hit. The one wildcard in that is when a driver is aggressive, and reacts aggressively to what they see as a challenge to their manliness or whatever. So by taking the lane, and then some, you may be putting yourself in more danger than in trying to give as much room as possible.

    That's really just my opinion. I both drive and ride though, so maybe I understand the cager mentality a little better, since I am one at least some of the time.

    Share the road goes both ways, and it's more than giving the other person the road, it's also the communication of a sprit of courtesy between road users.

    I don't do a lot of rural driving, but there is one stretch near my house that is still essentially rural, where a two-lane road goes under a train track. It's pretty tight under there, and the cars typically go 40-50 mph. I ride very near the white line most of the way, but as I approach the viaduct I control the lane. As soon as things get a little wider on the other side I give way and wave the cars through. Even though they are often frustrated at having to slow down, they seem to appreciate my active signal telling them they can pass.

    I realize riding long stretches of two-lane with little or no shoulder is different, but still there is something to be said for courtesy, even if the occasional cager is rude.

  4. I don't always agree with Doohickie (like on helmets), but this time, I think he's 100% on target. I call his wave, the "Keri Wave."

  5. Doohickie said (in part):

    "Share the road goes both ways, and it's more than giving the other person the road, it's also the communication of a spirit of courtesy between road users."

    Yielding lane position to make overtaking easier for faster traffic is not courtesy. The public road space is allocated on a first come first rights basis. The expectation that some traffic should yield their right of way for the convenience of someone else is up-ending ancient and established traffic rules.

    Part of our societies problem is that "traffic flow" is valued higher than an individuals safety or right of way. I am not willing to sacrifice that for a couple seconds of a motorist's time.

  6. I learned to drive (and ride) in the west (the real west, not in Fort Worth). There, we were taught to pull off the road if there were more than five vehicles following. We were taught this not considering that we might be riding bikes rather than slow motor vehicles.

    I think Doohickie says it all in this case. He's got some good company as well. John Forester says, "It is not a question of being shoved around, but of knowing how to help the other guy when it won't hurt you."

    John may be a contrary old cuss, but he makes some good points all the same...

  7. Doohickie also said:

    "It may not be your problem that the motorist gets aggravated, but it can be, at least in part, your fault. If taking the left tire track is viewed as aggressive, you have already kind of pissed off the other driver (maybe not your fault, but you're an influencing factor)."

    If a motorist is upset by being delayed by a cyclist, he will also be upset by the thousands of other delays he experiences on every trip. He will be delayed by red lights, stop signs, motorists pulling out in front of him and speed limits to name a few.

    When I drive on the public road, I do not impede traffic. I am traffic. Lots of folks get upset at traffic. Do we have any reasonable expectation for traffic to move out of our way?

    If the motorist's time were so important, he would be given a red light and siren, and I would be compelled to yield my right of way to him.

    The motorist has numerous alternatives. He can leave earlier to compensate for inevitable delays. It is not my responsibility to allow him to keep his schedule, and it is a foolish expectation.

    He can take a different route. Interstate highways for example. Motorists won't be delayed by bicycles there.

    The motorist can respect my right of way and overtake me when it is safe to do so by changing lanes to pass, just as he would any slow moving car. Just another 20 second delay among many on his trip.

    The annoyed motorist may not understand all the reasons why I ride where I do, and he may assume I am just being a jerk. I am not going to sacrifice my safety to avoid someone having bad thoughts about me.

  8. Steve A said:

    " There, we were taught to pull off the road if there were more than five vehicles following."

    I have never had five cars stacked up behind me. It's just not that hard to pass a cyclist.

  9. I've got to go with Doohickie and Steve A on this one... it's about 1)being safe 2)helping each other move it along. I'm not talking about yielding lane position when it's not safe, or at all for that matter, but that LH position you prefer still has the flaws outlined by Steve A, in my opinion. It seems to me you get the same safety advantages from RH lane or centre lane riding, and I too will ride on the right edge (not too close, though) when there's room.

  10. ChipSeal unearths another point when he notes he never has five cars stacked behind him. I get five cars stacked up pretty much every time I ride home on Westport (the only real way out of Alliance for those going east). The villain - excessive use of double yellow lines on those narrow, two-lane roads.

    The cars stack up east of Old Denton Road, where a pernicious double yellow line appears. Usually, one timid driver who merely wants to follow the law, with a pack of cars already behind him/her gets the stack set up. Sometimes a "Keri Wave" will help. Sometimes not.

    I didn't make the rules. I DO get to live with what results from them. What makes me most nervous is that fourth motorist back, with the anger management problem, when HE goes by...

  11. One good thing in the safe passing bill, if I remember right, is that it gives drivers the right to cross the double yellow if necessary when passing a vulnerable road user (as long as oncoming traffic permits).

  12. The double yellow provision is in Colorado's new three foot law, not in Texas's.

    It is rare for Texans to let some obscure law (Like no passing zones, prohibitions on passing on the right or on the shoulder.) prevent them from exercising their God-given right to travel at least the maximum speed limit!

  13. SA)#4 - If I look at the Sousa data, passing separation is best when traveling in the right tire track.
    While it is true that the largest average passing clearance can be achieved from the right tire track, the occasional deadly-close pass also occurs there. The closest pass in Dan & Brian's study happened when they were in the right tire track—when a pick-up squeezed between them and a Semi. This is a bigger issue on high-speed, multi-lane roads.

    I've done quite a lot of experimenting/observing with lane position and passing clearance. I find a position that is slightly left of the right tire track works well for me on 2-lane roads. I get mostly full lane changes, some straddle-passes, but rarely anything within 4 feet. I reserve the left tire track for when I don't want to be passed. That is often accompanied by a hand signal to reinforce the communication.

    OTOH, on a 4-lane road, I want to make it completely clear that the lane I'm in is mine. I ride center-left - left tire track, this almost always results in a complete lane change.

  14. I'm pretty sure it's in the Texas law too, Chipseal. But I know they've been dickering with it, so maybe not anymore.

    I was on a group ride Saturday. At a Stop sign there was a cop car just sitting there. I was paranoid about riding two (and even three) abreast in the group; I normally never do that. We all did rolling stops at the Stop sign; I think none of us noticed him until we rolled through. Just after we got through the intersection, a pickup truck passed us all by completely crossing the double yellow into the oncoming lane (pretty much right in front of the cop). The cop didn't hassle any of us.

    Not sure why I'm saying all this... just reporting my observations.

  15. Call me a traditionalist. I try to follow Forester, 1993 Sixth Edition, Chapter 29, "How Wide is the Road." Pages 293-298. I've never heard Forester repudiate that, and I've never seen any studies showing benefits from riding further to the left than what he advocated.

    Keri is correct in noting that the closest pass in the Sousa video was when they were in the RH tire track. However, they didn't test long enough to determine if this was a statistical oddity or something strongly related to RH tire track travel. I didn't see any reason it couldn't have as easily have happened in any other lane position.

    In my own experience, I've concluded that the critical position is to ride far enough left that the motorist automatically moves left to pass without actually having to think unless I can ride so the motorist can pass safely without changing position (wide lane). Anything more is in the "diminishing returns" category and, in the case of double-yellow two lane roads, may be counterproductive. I don't care whether a pass is a straddle pass or a full lane change as long as I'm not endangered by the pass. Motorists are generally more willing to violate the double yellow rule with a straddle pass.

    On my own commute, most places I'm best off to ride in the RH track, some places in the middle, and a few in the LH track. I'll even confess that in quite a few places, the fog line places me in exactly the postion that Forester advocates.

    Bottom line - learning these things is why bicycle commuting is about the safest cycling around...