Crash while avoiding cut off on 101 lanesplitting

[Honey Badger]

At 20mph, we are moving at approximately 29 feet per second. Most people take about 0.75 seconds to perceive a problem, and another 0.75 seconds to react.

So...we travel approximately 45 feet before doing anything to avoid the car that has that has begun to cut us off.

Slower is safer.

That video is great - judging by that, I'm pretty accurate with my estimates and self checks. 10 mph the vast majority of the time, 15 briefly for a few cars in certain situations, 20 makes me pucker (I've done it when i put myself in a bad position and one lane stopped and the other didn't, but NOT safe IMO).

If I had been going that fast in my first few years (heck, even until more recently) I would have been setting myself up for disaster knowing what I know now about my skills (versus what my "skills" at that time) and knowing far more about the capability or lack thereof of the bike...

 

[DataDan]

I just watched the video again; my delta is 10-15 average, 20 max if I'm feeling bold. Never as fast at 25 mph.

At 20mph, we are moving at approximately 29 feet per second. Most people take about 0.75 seconds to perceive a problem, and another 0.75 seconds to react.

So...we travel approximately 45 feet before doing anything to avoid the car that has that has begun to cut us off.

Slower is safer.

I'm more optimistic about reaction time than Enchanter, at least for a specific threat, predicted and prepared for--in this case a vehicle changing lanes across a lane-splitter's path. But even cutting his estimate in half (.75sec total to perceive and react), you're probably more vulnerable than you think.

Here's the scenario: You're splitting in otherwise bumper-to-bumper traffic, but up ahead there's a gap in one lane that invites a lane change from the other. If a driver does suddenly swerve into the gap, will you be able to avoid a crash by braking? It depends on how far ahead the incursion is and how fast you're going relative to the threatening vehicle.

Splitting at a 15mph speed differential, you will be able to brake and avoid a crash with a vehicle two car-lengths ahead--that is, the car whose rear bumper is 30 feet in front of you. You cannot avoid a crash if a vehicle one car-length or 15 feet in front of you swerves into your space.

The graph below shows that relationship, assuming .75sec reaction time and basic CMSP-level braking skill (0.5g) to slow to the lane-changer's speed. Notice how much the threat range increases with a small increase in speed. Slowing down has the opposite effect.

Use that knowledge to your advantage: When traffic on both sides is bumper-to-bumper as far as the eye can see, you can take advantage of higher splitting speed--up to the recommended +15mph if you're comfortable with that. But when the ebb and flow of traffic creates openings for lane-changers, slow down. That 15mph recommendation no longer applies. At +5mph or +10mph you have a much better chance of avoiding an incursion.

 

[sv650fromrwc]

Difficult to picture said scenario but I usually would immediately position myself on the left so I could potentially maneuver out of the situation.

 

[Schnellbandit]

Graphs and data are good reference points. Unfortunantly they can't account for the threat that results from the reactions of the driver who causes it.

Here is what I mean. If we accept the .75 second realization time and add the .75 physical reaction time, that time works on a distance to the perceived threat. The fly in the ointment is that we don't get to pick where that threat comes from nor the distance from it, there is no predictability of what any other driver will do. Even if we could use the data to come up with patterns, we can't predict how other drivers will react to what the first one does, we can't begin to even guess.

That .75 reaction time for perception of the threat is very generous, the reality is that the driver beeping their horn, the turn signal that came on to the right ahead, the driver flashing their high beams behind you all increase the time needed to process and realize the threat. More likely, the typical motorcycle rider takes far longer to realize the threat.

I'm basing this on the unclear recollections of so many crash reports, not a study of riders in a controlled environment where they know they are being tested or eye tracking studies to determine where and when bike riders scan traffic. Very often you hear something like "I was riding along and the next thing I know I was flying through the air" or " I don't know, next thing I was sliding on the ground". What that says is that there wasn't an awareness of the threat, the collision took place and only in retrospect could the rider guess or piece together what likely happened. This much is often obvious from the refinement of the story as others supply possible causes and what seems reasonable to have happened become the story.

There simply is no way to predict that the driver 3 miles ahead just getting on the freeway is going to weave into you because someone else blew their horn and he turned to look and sent you sailing.

The faster or slower speed within a range while lane splitting can't be answered from collected data because there are endless threat possibilities that can be affected by everything from someone needing to scratch their ass to the driver suddenly turning their windshield into a milky mess because they decided to turn on their wipers instead of the radio.

I vote for LA style carpool lanes where there isn't supposed to be lane changing except at control points but add a motorcycle only lane right next to it on the left side.

 

[Enchanter]

Schnellbandit, that's all good information but...

The Crash Analysis forum is intended to help the OP dissect this event to determine what they did that may have contributed to the event, and then provide them with feedback as to what they could do differently if they find themselves in a similar situation in the future.

Given this guidance regarding this forum, what did the OP do, or not do that contributed to the event, and what skill can you share with her that she can immediately apply in an attempt to address the issue described here?

 

[Schnellbandit]

Schnellbandit, that's all good information but...

The Crash Analysis forum is intended to help the OP dissect this event to determine what they did that may have contributed to the event, and then provide them with feedback as to what they could do differently if they find themselves in a similar situation in the future.

Given this guidance regarding this forum, what did the OP do, or not do that contributed to the event, and what skill can you share with her that she can immediately apply in an attempt to address the issue described here?

Immediate what comes to mind is that the OP said they weren't very good at judging distance. That would seem to be a very crticial skill since acceleration, braking, closure rates and so on all depend upon the rider being able to judge distance accurately.

Without knowing with good accuracy how far away you are from objects, especially those presenting a threat, reaction times are pretty meaningless. Identifying a threat must be put into some priority, is it something that can be avoided by changing vector, slowing or accelerating or a mix of some or all of those actions? Can the threat be acknowledged and will a warning to the driver posing the threat (if that is what it is) prompting them to action or to simply see you thus avoiding the bad result?

As the OP made a point to note this deficiency, perhaps some skill building exercises would help.

Motorcycle riders, because of their vehicle of choice, can change the distance to a threat much faster than drives in cars or trucks.

If you can't judge distance, it doesn't matter much how quickly the bike can stop or at what point a vector change becomes the worst thing to do instead of the best thing.

Given the inability to accurately judge distance, the reaction of the OP was degraded, suggestions as to what else the OP could have done is questionable since we don't know if the OP could take advantage of those opportunities given the scenario.

Knowing the performance envelop of the bike is critical. Practice acceleration and stops from various speeds and note the diatances. Compare those distances to known objects such as compact cars. Mid sized and large cars etc. Seat on the bike in a parking lot, practuce judging the distance to them. An easy way is the use even a cheao laser distance measure, they are sold at big box stores and places like Orchard supply and OSH too.

In summary, the OP (and anyone who rides and has difficulty judging distance) should seriously consider correcting the deficiency. With simple methods it is often possible to become very skilled at determining how far away objects are and from that know the proper course of action to avoid them if they also know the performance of motorcycle as well as their skill.level to implement them. Without that, it becomes a big hail mary hope instead of an informed risk assessment and coordinated reaction.

 

[Enchanter]

How does knowing the specific distance (in feet) help a motorcyclist determine what course of action to take? I suggest that it could only be useful if the rider knew a) their perception and reaction time, knew their exact speed at the moment in fps, and can do the calculation instantly. Oh, and they would need to do this for each of the other vehicles on the road at the same time.

I think that it is unreasonable and unrealistic to do that math on the road.

I think that they take-away here is that lane splitting past large gaps should be done with great care. If possible move over to the part of the lane farthest from the threat to increase the space cushion.

Occam's razor applies.

 

[tzrider]

How does knowing the specific distance (in feet) help a motorcyclist determine what course of action to take? I suggest that it could only be useful if the rider knew a) their perception and reaction time, knew their exact speed at the moment in fps, and can do the calculation instantly. Oh, and they would need to do this for each of the other vehicles on the road at the same time.

+1

I don't want to speak for the OP, but I think the comment about not being good at judging distance is to say that she can only approximate the distance for the purpose of describing what happened. I don't think she was identifying this as being a contributing factor in the incident. She was aware of her speed delta relative to other vehicles. That, being able to guess how much time you have to intersect with another vehicle and knowing whether you can brake or turn in that amount of time are the real factors we all work with. Translating these to units of measure for discussion isn't really necessary for safe riding.

 

[Schnellbandit]

fastride976#!

At 20mph, we are moving at approximately 29 feet per second. Most people take about 0.75 seconds to perceive a problem, and another 0.75 seconds to react.

So...we travel approximately 45 feet before doing anything to avoid the car that has that has begun to cut us off.

Slower is safer.

How does knowing the specific distance (in feet) help a motorcyclist determine what course of action to take? I suggest that it could only be useful if the rider knew a) their perception and reaction time, knew their exact speed at the moment in fps, and can do the calculation instantly. Oh, and they would need to do this for each of the other vehicles on the road at the same time.

I think that it is unreasonable and unrealistic to do that math on the road.

I think that they take-away here is that lane splitting past large gaps should be done with great care. If possible move over to the part of the lane farthest from the threat to increase the space cushion.

Occam's razor applies.

What kind of math are you referring to, the one you stated first or something else?

The point was that judging distance is an essential part of riding. There is no math involved :wow judging distance is like juding speed, you don't get out a calulator nor get distracted trying to figure it out.

If a rider doesn't know how far away they are from something then just how do they know if they can stop before running into it? Now that is unreasonable.

Just how does it help to know the distance to the car in front of you? Maybe to avoid hitting them when they jam on their brakes to stop because the guy in front of them did the same?

Crashes happen because of errors in judgement sparing mechanical failures and acts of god or nature. Isn't that the purpose here, to analyze the error, determine how to avoid similar situations and get better results?

Every rider should know the distance it takes for ther bike to stop as well as how quickly and it can pass another vehicle at speed. There is no math involved, its called being able to judge and that happens at the speed of thought and not by figuring out reaction times and converting that to distance or feet traveled at a certain speed. Geesh.

How does knowing the distance help avoid crashes? Well, if you are flying through two lines if cars and see the car some distance ahead closing the gap you will try to pass through it sure makes a difference if that is before or or after you realize you can't stop before running into them.

Knowing your position is all about distance, it helps you slow down or speed up, change what lane you are in or stay to the right or left . When splitting lanes knowing distance helps you decide if its worth the risk to split or just flow because 30 yards ahead the traffic is breaking free.

Op stated "The white car then unexpectedly did a quick lane change into my lane. Turned on blinkers after he crossed the white line. I was in a slight state of shock. He was maybe 10-20 feet in front of me. Again, I'm not good at gauging distance. "

She went on to say rhat she just knew she couldn't stop in time if she braked hard. Also, the car that crossed into her lane came from the right. OP said she saw a gap ahead and thought the white car wouldn't go there. Distance was impiortant. Closing to a gap on your left while splitting invites cars ahead on your right to slide in, which appears to have happened. A gap far ahead doesn't present the same danger as one 20 yards ahead. Speeding up places you closer to the gap and closer to cars on your right that want to dive into that space.

I suggest that knowing the distance it takes to stop is as important as much as being able to judge the difference between 10 and 20 feet. One is twice the other and 10mph is twice as fast as 5 mph. Without accurately judging distance, speed is just a number.

I povided some methods of being able to judge distance better. It might help the OP.

 

[Enchanter]

You mentioned getting out a laser measuring device as a method of measuring distance. I submit that most people are unable to judge the difference between 10-20ft when asked to do retrospectively / immediately following a crash. You are focusing in on one aspect of her post and missing or ignoring the rest.

Let's work from small to big. BIG = Motorcyclists need to be able to judge distance to threats. While this is an accurate statement, it doesn't really address the crash or the events immediately leading up to it. The actual distance to the car wasn't the problem. While splitting, it is impossible to be more than 10-20 ft away from other vehicles. The distance to the car wasn't the primary cause factor in this event. It was the gap in the other lane.

SMALL = When lane splitting, be wary of the gaps in the lanes. If there is a gap large enough for a car, assume they will move into it. If you must pass / continue to split, create additional space by moving into the gap in the other lane.

Please take some time to review the other threads in the CA Forum. This will give you the feel for the forum, how it is moderated, and what is expected.

 

[Schnellbandit]

In my experience, an analysis of something that goes wrong (in lay terms) results when many contributions, each with a small piece of a solution or solution come together in cooperation to improve the outcome for others that follow, the object incident has already happened.

I read the posts including those immediately preceding mine and saw the thread had taken a turn toward training and other directions and followed suit, my apologies for that.

I stand by my contribution however as it was only one view of a deficiency that could be improved and one of the methods I suggested, like watching a video someone else suggested was just a possible tool to help others, not something to become the focus of discussion. That it became that, I apologize again, the intent was a suggestion on how to improve distance judgement.

I saw the distance to the gap as critical. Not properly judging the distance to the gap or recognizing the danger to it contributed to what followed. It was the assumption the car would not move and the acceleration which led to the loss of control IMO. To me this is obvious and simple and not more complicated than that.

Most people do not ride motorcycles, therefore IMO, we need to do better than most.

If my analysis is not acceptable ok, the intent was to help.

 

[DataDan]

Most people--not just motorcyclists--are poor at judging distance, at least while traveling at road speed. "How far, in feet, to that dead squirrel?" is not something we're good at estimating.

We can, however, learn to judge travel time to a particular point. What makes this an easily learnable skill is feedback from counting out seconds. Estimating distance to the squirrel is merely a guess, and you don't know if you were even close. But a travel time estimate can be tested and, thus, refined. That's why MSF teaches riders (PDF) to think in terms of seconds, not feet:

• 12 seconds is the anticipated path of travel. It is where riders should generally look for factors that could develop into a hazard.
  
  
• 4 seconds is the immediate path of travel and approximates total stopping distance. It is the minimum time we need to stop or maneuver for an emergency.
  
  
• 2 seconds is the minimum recommended following distance [behind a vehicle traveling the same speed].

A travel time interval also has the advantage that it scales with speed. There's no need to calculate a following interval in terms of speed and car-lengths; just count out 2 seconds. Or, as the Brits teach, say: "Only a fool breaks the 2-second rule."

Travel time within the moving frame of reference of surrounding traffic is also helpful while splitting. A 10mph delta corresponds to about 1 second overtaking a normal-size car, back bumper to front bumper. And a gap in traffic that invites a lane change within a 4-second path demands immediate attention.


I don't know if the Lee Parks CMSP curriculum teaches this, but I'm interested in how they do it. Maybe that's a topic better suited to a Training thread.