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Posted by on Dec 18, 2008 in Safety | 11 comments

Spot the Hazards

hazardspot
In the illustration above, there are 2 cyclists approaching the back of a queue of traffic. The red cyclist intends to pass the queue on the right. The green cyclist intends to wait behind the queue and go through the intersection in the line of traffic.

Both cyclists need to watch for potential conflicts. Can you identify which hazards face the red cyclist, and which ones the green cyclist needs to identify? There are even potential conflicts the motorists need to look for. How might our cyclists predict the movements that are about to occur?

From the cyclists’ perspective some of the hazards are visible, others are not. A smart cyclist knows the generic conflicts (common crash types) that can happen at intersections. That was a hint. Other clues can be found here, here, here and here.

I made a little list of my own. I’ll be interested to see if you come up with things I missed.

11 Comments

  1. 1) The white car is preparing to turn right when he clears the parked vehicles. Other vehicles in the same queue may change plans and turn right from the straight ahead lane.
    2) The parked vehicles will open a door into the rider.
    3) The parked vehicles will pull out from the space into the rider.
    4) There is a pedestrian of unknown objective on two corners.
    5) The bus will make a wide right turn.
    6) The bus will pull over to pick up the pedestrian at the bus stop.
    7) The yellow car will turn in front of the rider.
    8) A Starbucks will suddenly appear on the corner, discharging pedestrians into the street without warning.

    How’d I do?

  2. That’s funny, an eight with a parenthesis becomes a smiley with sunglasses, totally unintentionally!

  3. Fred got a lot of them, but not all.

    There’s still a serious hazard for the red cyclist.

    There are various possibilities for all of them depending on the timing of the green light. Anyone have some scenarios?

    Break it down. What possible threats do the motorists face? What threats does the red cyclist face that the green one doesn’t? Are there any threats to the green guy that the red guy wouldn’t face?

    Bonus points for which pedestrian is most at risk of being hit while crossing the road legally and why.

  4. Even if nobody turns right, the red cyclist can easily get squeezed between traffic & the curb as the dweeb clears the intersection.

    I think the purple pedestrian is most at risk (of the pedestrians) because the red car’s driver is watching the major arterial and the purple’s also got a shot at getting taken out by the yellow car, depending on the light timing.

    The green cyclist is in danger of rear ending the white car when its driver hits the brakes suddenly (after starting forward), either when the bus turns right or when the bus driver sees the waiting fare ahead and simultaneously manages to avoid squishing the red guy against the curb. In this case, I think the green guy would be better off to filter forward between the traffic lanes and stop between the bus & green convertible. Maybe even wave thanks to the bus driver. That would get him clearly in the bus driver’s attention. Since there’s a fare waiting, it won’t delay the bus by as much as a tenth of a second. Being behind the green convertible will avoid getting creamed if its driver shoots forward to zip into the left lane when the light changes.

    By the way, if the green guy is opposed to filtering, hanging back a little as everyone moves into the intersection reduces his/her risk, mainly just irritating the cop right below the bottom of the diagram; who thinks cyclists ought to be in the gutter since that’s “practicable.”

  5. The red cyclist is at greater risk of being hit by a red light runner coming from the left if he hits the intersection on the new green and rolls immediately into the intersection; his view of the intersection is eclipsed by the bus.

    The rolling screen conflict noted by both Keri and Fred can happen to the green cyclist even though he’s taking the lane, because there’s another row of cars to his left. I’ve encountered that problem a couple times crossing northbound on Mills Ave. at Robinson (even with a bright orange shirt); the slight tangent to the approach aggravates it there. So that is a threat the green cyclist has that the red cyclist doesn’t, assuming the red cyclist is passing stopped vehicles.

    And, while it is admittedly a very, very minor risk, the green cyclist could get hit from behind by an oblivious motorist. Nearly happened to me on Colonial many years ago. I was waiting at the red light (cars ahead of me) and some nitwit locks up the brakes and skids up towards my rear end. Fortunately she stopped in time. Nearly peed my shorts.

  6. BTW Keri — this is an excellent type of learning exercise that could be applied to both cycling courses and to bicycle facility design courses. Now if you could just animate them… ;^)

    Also, we should keep in mind that not all risks are equal, either in probability or in severity, and that we don’t have very good objective data on either (though we experienced road warriors have a much better intuitive handle on them).

  7. Thanks, Mighk! I’m hoping to get through a tutorial book on Flash over the holidays so I can animate this kind of exercise.

    The degrees of risk are a very important component of this, as well as the ways of avoiding or mitigating them. People have an exaggerated view of the dangers of cycling, but the truth is, an aware and properly-riding cyclist has the ability to avoid almost all potential conflicts. Our 360° exposure to the environment and relatively slow speed actually gives us a safety advantage over motorists, as long as we pay attention and know a few basic things about traffic dynamics.

    The red cyclist faces risks that can be completely avoided. He’s doing what most cyclists do — riding along the edge and passing stopped traffic. He’s not a part of traffic. It’s something that happens beside him… and to him. His trajectory puts him outside the normal flow, in places where the other drivers aren’t looking because they are focused on common places for potential conflict.

    The green cyclist is acting (and being treated) like a vehicle driver. This cyclist still has risks that are faced by other vehicle drivers, particularly motorcyclists. That’s why our training is very similar to theirs.

    How could the green cyclist adjust for the moving screen or the rear-ender? (there are 2 motorcycle techniques for this)

    Steve mentioned the green cyclist rear-ending the car in front… I’ve almost done that (um, a few times). Hanging back is a good policy! When I’m in a line of traffic I stay on the left side. I’ve been able to avoid hitting a car by stopping to the left of it.

    If I was the green cyclist, I would not filter forward in front of the bus. I’ve had enough experience with Lynx drivers to prefer they are in front of me (some of them are courteous, I don’t intend to impugn them all).

  8. Oh, I forgot to add that Steve gets the bonus points for identifying the threat to the purple pedestrian.

    He’ll have a walk signal, but the driver of the red truck will be totally focused on finding a gap to turn right on red. At least the pedestrian can jump backwards, a sidewalk cyclist can’t do that.

    Pedestrians have a much harder time dealing with traffic than vehicular cyclists, especially around here.

  9. I’m late getting to the discussion, so I’ll take a slightly different tack: I am the green cyclist; I would not be the red cyclist. Here’s what I’ll be doing:

    My first concern is the bus because it’s big and can squash me like a bug. I’m positioned where I want to be — well away from those car doors. I’ll be allowing the bus and the white car plenty of room as they approach the intersection. I’m not going to get into a hurry and place myself too close. I’ll be invisible to the red and yellow cars. Another reason for no hurry: I can’t see around the darn bus, either.

    By the time I get to the blue parked car (assuming the red cyclist is still alive), I’ll be concerned first with the yellow car making the left turn. He’s missed the green arrow and may be antsy to poke his way through the intersection at the first opportunity. I need to make sure I’m clear when he does.

    In another second, but well before I enter the intersection, I’ll be concerned with the red car making the right. My goal now is to stay far left in the lane and make eye contact with BOTH drivers. I’m also going to glance at the first pedestrian just in case he’s of mind to jaywalk.

    Now I also need to be glancing in my mirror. I have to be ready to take evasive action if a driver in the left lane suddenly decides he needs change lanes. Will I go left or right if this happens? Hmmmmm… it will depend entirely on where this happens — before, during, or after the intersection. If before or during, I may be able to escape to the right. But if that bus goes to the bus stop and the guy pulls into my lane after the intersection, I better be ready for the big squeeze. I hope my breaks are in working order. Oh, but they are… I always check my systems before I ride.

    If the bus turns right (and misses the red cyclist), I’m feeling pretty good now to pass through the intersection — assuming eye contact has been made and rights of way established. I’ll take up a position mid lane — assuming more parked cars.

    If the bus goes straight, I’ll be watching for it to pull into the bus stop. If so, I’m going to continue as far left as I can be without crossing the line until that bus is out of my life.

    OK… do I survive?

  10. The pedestrian walking south could surprise the left turning motorist because he will be hidden from view by the bus.

    He could stop in the lane in front of the green cyclist if he focuses on jumping the gap and fails to see the pedestrian before he begins his turn.

    Any hazard facing the green cyclist (Left cross, pull out and the bus stopping or turning.) can be perceived sooner than the hazards faced by the red cyclist. (Right hooks, dooring, curb bulb out, pedestrian encroachment and the bus stopping.)

    Also, the green cyclist has more avenues of escape then the red cyclist, and is mitigating most of them by being more visible. (As Keri points out, where other road users are expecting to see traffic.)

    Great fun, Keri! Tailwinds!

  11. Keri,
    If I saw that multiple drivers were signaling right turns in the right lane, I would probably transition to the left lane and pass all of the slowing/turning “pokey” drivers before I moved back to the right hand lane; usually after passing through the intersection. This gives me the most margin against movement conflicts and sight line problems. I don’t normally waste much time mentally enumerating all of the myriad ways in which curb-hugging may get me into trouble. My traffic cycling motto is very simple: When in doubt, move leftward!

    - Dan -