One of the things my SAT students discuss is driving, drivers' ed., and road tests. During break I was privileged to overhear the following:
"...so this other car wasn't moving, and I could hear the woman sighing, like she was waiting for me to go, so finally I went. And then she's writing something and I'm trying to see what it is and I got distracted and I ran through a stop sign. She said 'stop, you've failed.' So that's the second time that I've failed."
Showing posts with label driving. Show all posts
Showing posts with label driving. Show all posts
Friday, March 21, 2008
Thursday, March 6, 2008
Delegation of authority: the brain and the spinal cord
We tend to think of our brain as being the processing center of our body, making all decisions and directing all activity. The truth is that, while the brain does direct the actions of our body, it delegates a lot of control to the spinal cord.
The most obvious example of this is our reflexes. When you touch a hot stove, you reflexively withdraw your hand; the pain signal travels to your spinal cord and directly triggers the nerve circuit that activates the muscles in your arm, so by the time your brain is aware of what is happening, your hand has already been safely removed from danger. This is good, because it reduces the amount of time that our hand is on the stove, and so reduces the amount of damage we sustain.
Similar to this is the stretch reflex. When we receive something into our hands, we mentally estimate how much the object will weigh. We then activate enough of the cells in each muscle to exactly balance that estimated weight, and usually we're pretty close. Our hand might fall or rise slightly as we fine tune the amount of force we use to hold the object, but the movement is minor and smooth. If our estimate is far off, however, there is a more violent reaction. If we underestimate the weight, the object falls, and pulls our hand down with it, and we quickly exert more force to prevent the object from slipping out of our hands. This reflex, whether it is the fine adjustments of the first scenario or the gross adjustments of the second, are also regulated at the spinal cord.
Walking is a more complex example. As we learn to walk, much of the processing and regulation is done by the brain. Once we're adept walkers, however, the task is handed off to the spinal cord, with the brain only providing general directions. More specifically, the brain determines the direction and speed, and the spinal cord takes care of moving the feet.
Climbing or descending stairs is handled similarly, with one exception. Walking involves flat ground - whether we walk on the street or in our homes; the experience is the same. Stairs add a third dimension, and the amount we have to figure out how much to raise our foot for each step if we are to gracefully climb the stairs rather than trip and fall on them. Here, the brain steps in briefly - we look at the beginning of a staircase, using eye-foot coordination to safely land our feet on each of the first two steps, but if we're dealing with a regular staircase (i.e. each step is the same height and the same depth) our spine takes the height and depth information and plugs it into the general procedure for climbing stairs. At this point we focus our brain's attention, and our eyes, somewhere else until we reach the other end of the stairs, when our brain tunes in again to issue a "stop climbing stairs, start walking" order.
As with many phenomena, this is most obvious when something goes wrong. If you've ever tripped over an extra-high step in the middle of a staircase, or placed your foot down heavily on a step that wasn't as tall as those before it, you've experienced a case where the spinal column expected a step to be in one place, and directed your leg muscles to put your foot there - where the step turned out not to be. Your brain then steps in to clear up the confusion, and you're on you're way again.
Incidentally, this is a reason to be careful with home-made stair cases - the top and/or bottom steps are often of a different height than the rest of the staircase (building a set of stairs properly is more difficult than you might think).
And, no surprise, perhaps, this brings me back to driving once again. Much of driving is routine, and over time I expect that we hand off a lot of control to our spinal cord, and we turn our attention elsewhere. Unfortunately, the consequences of blithely missing a step, though occasionally severe, rarely approach the seriousness of blithely driving our car into an accident.
Inspired by: http://www.ethanhein.com/memebase/solving_problems/darwin_saves.html#saccade.
The most obvious example of this is our reflexes. When you touch a hot stove, you reflexively withdraw your hand; the pain signal travels to your spinal cord and directly triggers the nerve circuit that activates the muscles in your arm, so by the time your brain is aware of what is happening, your hand has already been safely removed from danger. This is good, because it reduces the amount of time that our hand is on the stove, and so reduces the amount of damage we sustain.
Similar to this is the stretch reflex. When we receive something into our hands, we mentally estimate how much the object will weigh. We then activate enough of the cells in each muscle to exactly balance that estimated weight, and usually we're pretty close. Our hand might fall or rise slightly as we fine tune the amount of force we use to hold the object, but the movement is minor and smooth. If our estimate is far off, however, there is a more violent reaction. If we underestimate the weight, the object falls, and pulls our hand down with it, and we quickly exert more force to prevent the object from slipping out of our hands. This reflex, whether it is the fine adjustments of the first scenario or the gross adjustments of the second, are also regulated at the spinal cord.
Walking is a more complex example. As we learn to walk, much of the processing and regulation is done by the brain. Once we're adept walkers, however, the task is handed off to the spinal cord, with the brain only providing general directions. More specifically, the brain determines the direction and speed, and the spinal cord takes care of moving the feet.
Climbing or descending stairs is handled similarly, with one exception. Walking involves flat ground - whether we walk on the street or in our homes; the experience is the same. Stairs add a third dimension, and the amount we have to figure out how much to raise our foot for each step if we are to gracefully climb the stairs rather than trip and fall on them. Here, the brain steps in briefly - we look at the beginning of a staircase, using eye-foot coordination to safely land our feet on each of the first two steps, but if we're dealing with a regular staircase (i.e. each step is the same height and the same depth) our spine takes the height and depth information and plugs it into the general procedure for climbing stairs. At this point we focus our brain's attention, and our eyes, somewhere else until we reach the other end of the stairs, when our brain tunes in again to issue a "stop climbing stairs, start walking" order.
As with many phenomena, this is most obvious when something goes wrong. If you've ever tripped over an extra-high step in the middle of a staircase, or placed your foot down heavily on a step that wasn't as tall as those before it, you've experienced a case where the spinal column expected a step to be in one place, and directed your leg muscles to put your foot there - where the step turned out not to be. Your brain then steps in to clear up the confusion, and you're on you're way again.
Incidentally, this is a reason to be careful with home-made stair cases - the top and/or bottom steps are often of a different height than the rest of the staircase (building a set of stairs properly is more difficult than you might think).
And, no surprise, perhaps, this brings me back to driving once again. Much of driving is routine, and over time I expect that we hand off a lot of control to our spinal cord, and we turn our attention elsewhere. Unfortunately, the consequences of blithely missing a step, though occasionally severe, rarely approach the seriousness of blithely driving our car into an accident.
Inspired by: http://www.ethanhein.com/memebase/solving_problems/darwin_saves.html#saccade.
Thursday, January 3, 2008
Don't surrender your common sense to your GPS
Yesterday, a commuter train hit a passenger car in Bedford Hills, New York. News reports state that the car's driver turned onto the tracks at the bidding of his GPS system, and mistook the tracks for the parkway that lay just beyond them.
Reports were unclear as to whether the man didn't realize that there was a railroad crossing at that location, or whether he thought he had safely passed through it when he made the turn onto the tracks, but I don't know that that matters. Photos of the wreck site show that the crossing is marked on each side with traditional cross bucks, wig-wags (the flashing red lights) and gates that lower over the roadway. A round "RAILROAD" sign appears before the crossing. To not realize that there was a railroad crossing he'd have to ignore the first set of signs and gates; to think he was through the crossing, he'd have to ignore the second set (those turned toward the traffic coming the other way - he wouldn't be able to read the signs, but those cross-bucks and the gate are unmistakable from either side). Admittedly, this all occurred after sundown, and the red lights at the crossing wouldn't have been flashing (time passed between his getting stuck and the arrival of the train), but a railroad-crossing cross buck is pretty obvious for what it is, and I have to assume that he had his headlights on.
I can therefor only guess that the driver wasn't paying attention. He surrendered his own judgment to the GPS unit, and when he heard it, or thought he heard it tell him to turn right, he complied without considering the advisability of doing so. And I'm not terribly surprised that he did, because we surrender a lot of our judgment to signs and traffic signals when we drive. The traffic light is green, and I proceed without stopping or even slowing to look for cross traffic. And this is the right thing to do, if we wish to use our roadways with anything approaching efficiency, but we have to be careful not to surrender too much, as this man clearly did.
It is probably our faith in signs and signals that leads us to believe that we can multi-task as we drive - we eat, drink coffee, fiddle with our CDs as we drive down the road. We talk on our cell phones, either using a hands-free unit or not. We shave. We put on makeup. Usually we get away with it, but incidents like this one remind us that we won't, always, so hang-up your cell phone, put down your CDs, and pay attention to what you're doing.
* No injuries were reported in connection with this accident
* The driver of the wrecked car and the company he rented it from are being held liable for the damage to the train and tracks, plus lost revenue and other expenses which are expected to total hundreds of thousands of dollars
* NTSB's database of railroad accidents
Reports were unclear as to whether the man didn't realize that there was a railroad crossing at that location, or whether he thought he had safely passed through it when he made the turn onto the tracks, but I don't know that that matters. Photos of the wreck site show that the crossing is marked on each side with traditional cross bucks, wig-wags (the flashing red lights) and gates that lower over the roadway. A round "RAILROAD" sign appears before the crossing. To not realize that there was a railroad crossing he'd have to ignore the first set of signs and gates; to think he was through the crossing, he'd have to ignore the second set (those turned toward the traffic coming the other way - he wouldn't be able to read the signs, but those cross-bucks and the gate are unmistakable from either side). Admittedly, this all occurred after sundown, and the red lights at the crossing wouldn't have been flashing (time passed between his getting stuck and the arrival of the train), but a railroad-crossing cross buck is pretty obvious for what it is, and I have to assume that he had his headlights on.
I can therefor only guess that the driver wasn't paying attention. He surrendered his own judgment to the GPS unit, and when he heard it, or thought he heard it tell him to turn right, he complied without considering the advisability of doing so. And I'm not terribly surprised that he did, because we surrender a lot of our judgment to signs and traffic signals when we drive. The traffic light is green, and I proceed without stopping or even slowing to look for cross traffic. And this is the right thing to do, if we wish to use our roadways with anything approaching efficiency, but we have to be careful not to surrender too much, as this man clearly did.
It is probably our faith in signs and signals that leads us to believe that we can multi-task as we drive - we eat, drink coffee, fiddle with our CDs as we drive down the road. We talk on our cell phones, either using a hands-free unit or not. We shave. We put on makeup. Usually we get away with it, but incidents like this one remind us that we won't, always, so hang-up your cell phone, put down your CDs, and pay attention to what you're doing.
* No injuries were reported in connection with this accident
* The driver of the wrecked car and the company he rented it from are being held liable for the damage to the train and tracks, plus lost revenue and other expenses which are expected to total hundreds of thousands of dollars
* NTSB's database of railroad accidents
Wednesday, December 12, 2007
I hate rubberneckers
Honestly, I hate rubberneckers. These are those people who, on driving past a motor vehicle accident, or even just someone who has been pulled over for speeding, turn to look at the accident or motorist instead of paying attention to where they're driving. You're going to steer your car toward whatever you're looking at (consider the moth effect). Your car weighs a ton, minimum; pay attention to where you're driving!
Sunday, December 9, 2007
Speed limits don't work, reprise
In a previous post, I commented on how speed limits don't successfully regulate traffic speed. On my drive home today I realized that if they did successfully regulate speed, they would be problematic.
Speed limits often apply to long stretches of road, which typically include straight and curved portions. On a curve, of course, some of the tires' griping force must be devoted to turning the car; on a straight road all of the grip can be applied toward propelling the vehicle, or stopping it, should the need arise. So, straightaways can safely be driven faster than curves. The condition of the road may vary widely, too, within the area of a single speed limit. Inclement weather must also be considered, as must lighting and other traffic. I'll leave to the side considerations on the type and condition of the vehicle, and the skill and condition of its driver.
The point of all of this is that applying a single speed limit to a stretch of road within which these variables vary is misleading, as it suggests that the entire stretch can be driven at that speed. A driver following this suggestion will then either take some portions of the road too fast, or other portions too slow.
What's the solution? Short of a fully automated roadway system with fully automated cars, I don't know, but it certainly isn't more speed limit signs.
Speed limits often apply to long stretches of road, which typically include straight and curved portions. On a curve, of course, some of the tires' griping force must be devoted to turning the car; on a straight road all of the grip can be applied toward propelling the vehicle, or stopping it, should the need arise. So, straightaways can safely be driven faster than curves. The condition of the road may vary widely, too, within the area of a single speed limit. Inclement weather must also be considered, as must lighting and other traffic. I'll leave to the side considerations on the type and condition of the vehicle, and the skill and condition of its driver.
The point of all of this is that applying a single speed limit to a stretch of road within which these variables vary is misleading, as it suggests that the entire stretch can be driven at that speed. A driver following this suggestion will then either take some portions of the road too fast, or other portions too slow.
What's the solution? Short of a fully automated roadway system with fully automated cars, I don't know, but it certainly isn't more speed limit signs.
Monday, November 26, 2007
Why the ambulance crew doesn't wear their seatbelts
This is another one on risk:
It used to strike me as strange that EMTs and paramedics typically don't wear their seatbelts. I don't mean in the back of the ambulance during a call. It's hard to be belted in and still treat the patient (though there are some harness systems designed to meet this purpose). But up front, or in the back when there's no patient (say, on the way to a call) - no seatbelt. I have also seen a lot of orthopedic surgeons who ride motorcycles, and almost every respiratory tech that I've ever met smokes.
My theory on this? I think that these people are brought face to face with human misery, and with the frailty of the human body, much more often than is healthy. Eventually, one of two things happens. Either they recognize those human frailties in themselves, and either change careers or go mad with it; or they decide that they're immune. "I won't get COPD or lung cancer from cigarettes, and I'll prove it by smoking them and not getting sick." "My body is not fragile, and I'll prove it by riding a motorcycle, not wearing my seatbelt, etc." "I'm too good a driver to get in an accident," etc, etc. "I am imune."
Which brings me to another point. If I'm putting on my seatbelt when I get into your car, don't be offended. It isn't necessarily your driving that I'm worried about. It's every other driver on the road.
Or be offended, if you want. Because maybe it is your driving that I'm worried about.
[Risk link added 28 Nov 2007]
It used to strike me as strange that EMTs and paramedics typically don't wear their seatbelts. I don't mean in the back of the ambulance during a call. It's hard to be belted in and still treat the patient (though there are some harness systems designed to meet this purpose). But up front, or in the back when there's no patient (say, on the way to a call) - no seatbelt. I have also seen a lot of orthopedic surgeons who ride motorcycles, and almost every respiratory tech that I've ever met smokes.
My theory on this? I think that these people are brought face to face with human misery, and with the frailty of the human body, much more often than is healthy. Eventually, one of two things happens. Either they recognize those human frailties in themselves, and either change careers or go mad with it; or they decide that they're immune. "I won't get COPD or lung cancer from cigarettes, and I'll prove it by smoking them and not getting sick." "My body is not fragile, and I'll prove it by riding a motorcycle, not wearing my seatbelt, etc." "I'm too good a driver to get in an accident," etc, etc. "I am imune."
Which brings me to another point. If I'm putting on my seatbelt when I get into your car, don't be offended. It isn't necessarily your driving that I'm worried about. It's every other driver on the road.
Or be offended, if you want. Because maybe it is your driving that I'm worried about.
[Risk link added 28 Nov 2007]
Thursday, October 25, 2007
Turn signals aren't about fashion
I was walking across a parking lot today when I saw one of those cars (an SUV, actually) whose rear turn signal were blue - the bulb was blue, behind a clear lens. Now, I've already gone-off about how most people are bad drivers, but since 95% of driving is routine, it only matters 5% of the time, so it won't surprise you when I say that this is the kind of setup that I don't like. Here in New York State, a flashing blue light is a volunteer firefighter or the rear-end of some other emergency vehicle; blue turn signals fall into the category of WTF is that!? And WTF is one of the last things that a driver should have to worry about.
Clear lenses on tail lights are just as bad, during the day. They make the back end of the car look like the front end. Is that car coming toward me, or going away from me? Again, WTF?
Clear lenses on tail lights are just as bad, during the day. They make the back end of the car look like the front end. Is that car coming toward me, or going away from me? Again, WTF?
Monday, October 8, 2007
Tailgaters suck
On the parkway yesterday some moron in a white SUV followed me so closely that I couldn't see his headlights in my rear view mirror. I won't tell you how fast I was going (I don't want to receive a ticket in the mail), but I was will tell you that I was traveling at highway speed.
Of all of the moronic things that drivers do, this may be the one that most angers me. Because if something happens right in front of me, I have to choose between swerving and rolling over, hitting it, or slamming on my brakes - at which point the car behind me winds up in my back seat.
The irony is that if he manages to avoid me, and to avoid rolling over, he'll have successfully reinforced his asinine behavior ("I didn't have an accident; of course I can follow that close"). And if he does rear-end me, well, I shouldn't have slowed down that fast, right?
If only I could drop caltrops from the back of my car.
Of all of the moronic things that drivers do, this may be the one that most angers me. Because if something happens right in front of me, I have to choose between swerving and rolling over, hitting it, or slamming on my brakes - at which point the car behind me winds up in my back seat.
The irony is that if he manages to avoid me, and to avoid rolling over, he'll have successfully reinforced his asinine behavior ("I didn't have an accident; of course I can follow that close"). And if he does rear-end me, well, I shouldn't have slowed down that fast, right?
If only I could drop caltrops from the back of my car.
Sunday, September 30, 2007
My village is not your trashcan
I was driving home today, and someone in the car front of me at the stoplight tossed a cigarette pack out onto the street. I was reminded of a story I heard of someone braver than I: when this guy saw someone drop a cigarette butt on the floor or street, he would pick it up and approach the offender, "Excuse me, but you dropped something" The offender would then typically put out his hand to receive whatever he had dropped, and would receive the cigarette, ember end down (and often still hot) into their hand.
If I had more courage I'd do that. And I'd have done something similar here, too. Instead I just sat there in frustrated anger.
Back when I was a kid I remember going to Shea Stadium for a friend's birthday. A woman sitting in front of us (and upwind of us, more importantly) refused to stop smoking, though we asked her politely. Eventually we chanted "Lets Go Mets!" for several innings straight and filled the hood of her sweatshirt with peanut shells. I don't know that it was appropriate but it sure made us feel better.
Maybe I should start driving around with a bag of empty peanut shells: you litter in my village, I litter in your car.
If I had more courage I'd do that. And I'd have done something similar here, too. Instead I just sat there in frustrated anger.
Back when I was a kid I remember going to Shea Stadium for a friend's birthday. A woman sitting in front of us (and upwind of us, more importantly) refused to stop smoking, though we asked her politely. Eventually we chanted "Lets Go Mets!" for several innings straight and filled the hood of her sweatshirt with peanut shells. I don't know that it was appropriate but it sure made us feel better.
Maybe I should start driving around with a bag of empty peanut shells: you litter in my village, I litter in your car.
Friday, September 28, 2007
The siren song of the ambulance
Driving with the lights and siren is some of the most exhilarating and some of the most stressful driving I do. On the one hand, I get to drive fast; proceed through a red light; drive around slow, stopped traffic by crossing over the double-yellow, and of course there's all of the excitement of the call. On the other hand, I need to maneuver around drivers who drive erratically on my approach, who fail to yield because they don't hear me or simply don't care, and I'm worried about arriving too late. Oh, and the ambulance handles like a pig. A top-heavy pig.
All of this makes the driving more complex, and more demanding, but there's also the two-way radios (we've got four in each ambulance, each with several channels to chose from) the Nextel, the airhorn, and the siren. I can switch the siren over to hands-free, but then I lose my electronic airhorn (although really, it's the real airhorn that clears traffic - that thing sounds like a freight train). There's also the PA. Thank God the ambulance has an automatic transmission.
So, why do I do it? Well, there are a few reasons:
* I get to drive fast, proceed through red lights, etc
* I get to turn on the flashing lights and the siren
* I occasionally get to use theGod microphone PA: "Please move to the right" (the PA is an often overlooked asset that few drivers use, and even fewer use well, but more on that in another post)
* I get to save lives, treat the injured, etc, but...
* ... if the patient throws up, he doesn't do so on me
All of this makes the driving more complex, and more demanding, but there's also the two-way radios (we've got four in each ambulance, each with several channels to chose from) the Nextel, the airhorn, and the siren. I can switch the siren over to hands-free, but then I lose my electronic airhorn (although really, it's the real airhorn that clears traffic - that thing sounds like a freight train). There's also the PA. Thank God the ambulance has an automatic transmission.
So, why do I do it? Well, there are a few reasons:
* I get to drive fast, proceed through red lights, etc
* I get to turn on the flashing lights and the siren
* I occasionally get to use the
* I get to save lives, treat the injured, etc, but...
* ... if the patient throws up, he doesn't do so on me
Wednesday, September 19, 2007
Driving safely
A few days ago, I went off on how people generally drive badly, but I realize that I didn't indicate what good, safe driving actually consists of. So I thought I'd make a few comments on that, since I get the sense that this is a bit of a mystery to some folks.
Mind you, this is not an all inclusive description...
On learning to drive, a former girlfriend of mine said that the basic deal was to yield to anything that moves, and make no sudden movements. This encapsulates a few of the core principles of safe driving:
* if you hit something, you'll damage it, so go to great lengths not to hit anything;
* if you hit someone, you'll damage her/him/etc, so go to great lengths not to hit anyone;
* you won't always be able to see the people around you, so be sure to give them adequate warning of your actions so they can get out of the way;
* you won't always be able to see the vehicles around you, so be sure to give them adequate warning of your actions so they can get out of the way;
all of which seems pretty simple. Use the steering wheel to go around people, and use the brake pedal to stop before you hit them. Oh, and be sure to use your turn signals before turning, because there might be a bicycle in your blind spot. And use your turn signals before changing lanes, because there might be a car in your blind spot.
Note that using your signals as you turn or change lanes isn't the same thing. If I don't turn on my signal until I'm actually changing lanes, I'm going to hit you before you'll have a chance to see my signal and react to it.
Because that is the point of the signal: to give warning of what your car is about to do, and to give that warning early enough for everyone else to react to it.
Glancing toward your blind spots is also probably a good idea before changing lanes. Even if you've been good about signaling, there's no guarantee that the guy in the next lane is paying attention.
Speed is another issue. Not the speed limit, but the speed and relative speed of vehicles on a street. Speed is important because, as graduates of high school physics may remember, the (kinetic) energy of a car is proportional to the square of its speed (so if I double the speed, I quadruple the energy). And if I double my speed, I'm going to more than double (quadruple?) the distance I'll need to stop before I hit Granny as she crosses the street; all of which means that the length of road in front of me that I need to worry about becomes increasingly large. God help me if I'm only a carlength behind that 18 wheeler.
Which brings me to another point, one that I learned personally several years back. I was driving south on I-95 through Connecticut, and I was, in retrospect, following an SUV too closely. The SUV eventually changed lanes, getting out of my way, but I wasn't the reason it moved: the dead deer in the roadway was. I didn't see the deer until I was on top of it, since my view was blocked by the SUV. (Yes, I did hit the deer; no, I didn't die). Lesson: the closer you get to the vehicle in front of you, the more it obstructs your view.
I'll pass over what might have happened if the driver of that SUV had stood on his brake pedal instead of changing lanes.
Okay; enough for now. Be careful out there.
Mind you, this is not an all inclusive description...
On learning to drive, a former girlfriend of mine said that the basic deal was to yield to anything that moves, and make no sudden movements. This encapsulates a few of the core principles of safe driving:
* if you hit something, you'll damage it, so go to great lengths not to hit anything;
* if you hit someone, you'll damage her/him/etc, so go to great lengths not to hit anyone;
* you won't always be able to see the people around you, so be sure to give them adequate warning of your actions so they can get out of the way;
* you won't always be able to see the vehicles around you, so be sure to give them adequate warning of your actions so they can get out of the way;
all of which seems pretty simple. Use the steering wheel to go around people, and use the brake pedal to stop before you hit them. Oh, and be sure to use your turn signals before turning, because there might be a bicycle in your blind spot. And use your turn signals before changing lanes, because there might be a car in your blind spot.
Note that using your signals as you turn or change lanes isn't the same thing. If I don't turn on my signal until I'm actually changing lanes, I'm going to hit you before you'll have a chance to see my signal and react to it.
Because that is the point of the signal: to give warning of what your car is about to do, and to give that warning early enough for everyone else to react to it.
Glancing toward your blind spots is also probably a good idea before changing lanes. Even if you've been good about signaling, there's no guarantee that the guy in the next lane is paying attention.
Speed is another issue. Not the speed limit, but the speed and relative speed of vehicles on a street. Speed is important because, as graduates of high school physics may remember, the (kinetic) energy of a car is proportional to the square of its speed (so if I double the speed, I quadruple the energy). And if I double my speed, I'm going to more than double (quadruple?) the distance I'll need to stop before I hit Granny as she crosses the street; all of which means that the length of road in front of me that I need to worry about becomes increasingly large. God help me if I'm only a carlength behind that 18 wheeler.
Which brings me to another point, one that I learned personally several years back. I was driving south on I-95 through Connecticut, and I was, in retrospect, following an SUV too closely. The SUV eventually changed lanes, getting out of my way, but I wasn't the reason it moved: the dead deer in the roadway was. I didn't see the deer until I was on top of it, since my view was blocked by the SUV. (Yes, I did hit the deer; no, I didn't die). Lesson: the closer you get to the vehicle in front of you, the more it obstructs your view.
I'll pass over what might have happened if the driver of that SUV had stood on his brake pedal instead of changing lanes.
Okay; enough for now. Be careful out there.
Sunday, September 16, 2007
We don't pay as much for gasoline as we should
Some time in the late '90s I drove through that spit of Canada between Michigan and Niagra Falls. Gasoline was advertised there at 80 cents per liter, which works out to a little over three dollars (Canadian) per gallon. I knew at the time that we paid very little for gasoline, compared to the rest of the world, but this was the first time I came face to face with the issue. I thought then, as I still do, that here in the US we should be paying prices on par with the rest of the world.
I realize that this is something of a self-defeating position. I enjoy driving, and I do a fair bit of it - gasoline forms a very real part of my expenses - and I don't have money to spare. But I also realize that it is because of the low price of gasoline that Americans neither invest much in public transit, nor use it. I think that the availability of gasoline has also fed into the American notion that driving is a God-given right, rather than a privilege to be granted only to those who can show adequate mastery of the necessary skills.
I am not the first to point out that our nation's dependence on oil, including foreign oil, has created real international and political problems for us. I doubt that I'm the first to propose that the low price of gasoline has reinforced that dependence by encouraging oil use and discouraging investigation and investment in alternative energy sources.
If I lived in a warmer climate, I'd probably use used vegetable oil for fuel; it's just too cold here during the winter, and I can't afford to keep two vehicles.
Since oil is an exhaustable resource, we do need to develop alternate energy sources. Unfortunately, we don't tend to invest in the future - we defer maintenance on our bridges, and prefer to treat the uninsured in the ER rather than provide them with insurance. We also seem to be devoid of a sense of personal responsibility ("Yes, I realize that my client was hypertensive, obese, had coronary artery disease and a family history of cardiac disease, and had spent the morning shoveling snow (that well-known trigger of heart attack), but it was the Vioxx that caused his heart attack.") So we need some sort of a kick to get us to act. I've long thought that high gasoline prices would provide that kick, though three dollars per gallon doesn't seem to have done very much. Maybe we need to wait for regular to go to $6.59 per gallon.
We probably won't be waiting very long.
Monday, September 10, 2007
Most of us are bad drivers, but usually it doesn't matter
When I was learning to drive the ambulance, our director said, as part of our training, "remember: 90% of driving is routine. It's when the routine is broken that accidents happen." Her point was that an emergency vehicle, in proceeding through a red light, driving left of the double yellow line, proceeding the wrong way down a one way street, etc, was breaking the routine, so extra caution was necessary to do so.
I now think that she underestimated the amount of driving that qualifies as routine - I'd put the number closer to 95% or even 99%, but her basic point is correct. We know to stop at a stop sign, and we know, too, that it is the rare driver who actually stops - most of us slowly glide through if we can do so; the ride is much more comfortable. We know which side of the road to drive on - when faced with a double-yellow line we don't have to think about how to react to it. We know that the amber light on the traffic signal heralds the red, so we'd better mash the gas so we don't have to wait the 40 seconds for the green light to come back; most of us seem to have forgotten that the amber light actually means "stop if you can do so safely". We are familiar with the flow of traffic and our place in it, we call upon our experience, and most of the time, things go well.
Problems arise when things don't go as we expect. A tire blows and our control of our car is reduced. The road surface changes drastically, and again our control is reduced. We have a green light, but due to a streetlight malfunction, we also have a red light - as does everyone else: we all proceed into the intersection and collide. But unless this happens, we tend to arrive safely at our destination, in spite of our efforts to the contrary.
Because we do actively undermine our safety. We drive too fast, we follow too close, we distract ourselves with coffee, donuts, cellphones, and reading directions. We never check the pressure on our tires. We don't read the owner's manual to our vehicles. Many of us can't be bothered to wear a seatbelt. We drive when we're impaired by drugs (typically ethanol, though OTC and prescription drugs, and other drugs are also sometimes to blame) or a lack of sleep. Because driving is easy, right?
Well, no. Or maybe more accurately, driving is easy, but driving safely is not.
This isn't necessarily our fault. We're used to our own scale, and we're designed to react to our own scale. If I weigh 140 lbs, then I'm used to moving 140 lbs around; I have a sense of how fast I can accelerate, and how fast I can stop, how tightly I can turn. If I want to pick up a heavy box, I know that the effort require to do so will relate directly to the mass/weight of that box - there's an intimate feedback that lets me know how much weight I'm dealing with, and thus how careful I need to be as I move that weight.
A small car, though, weighs about one ton. Large SUVs exceed four tons, and large trucks can weigh much more than that, but I can get those tons of machinery to move with less effort than it takes to walk - I just press on the accelerator. if I want to change my direction, I move my arm and twist a wheel, and I've probably got power steering in case that's too difficult. Stopping takes the push of a different pedal; that probably has power assist, too. The feedback is lost. The ease with which I can get the car to move belies the potential difficulty I will have in bringing it to a stop. So without meaning to, I drive too fast, follow too close. My success as a pedestrian complicates my job as a driver.
There is also the theory of risk tolerance, or risk homeostasis. According to this theory, we each have a degree of risk with which we are comfortable, though this varies between individuals. If our risk is reduced, we are willing or driven to take steps to raise the level of risk to the our level of comfort. For instance, if my car has antilock brakes, I am willing to drive the car harder and demand more of the braking system, and my likelihood of crashing remains the same. As our roads get safer, we drive faster. Similarly, safer cars yield higher speeds. I think there is something to this - armed with air bags, some drivers refuse to wear seatbelts (which is one of the more idiotic examples, as the airbag requires the seatbelt if it is to be effective, say nothing of the possibility of being hit multiple times in the same incident).
It is thus not surprising that some emergency workers have started to use the term motor vehicle collision (MVC) instead of motor vehicle accident (MVA). with all that we do to undermine our safety, they argue, a collision is waiting to happen, and is no accident. (In a similar vein, some medical practicioners are abandoning the term cerebrovascular accident (a term that includes strokes and transient ischemic attacks).)
More on this later - this post is getting to be too long.
I now think that she underestimated the amount of driving that qualifies as routine - I'd put the number closer to 95% or even 99%, but her basic point is correct. We know to stop at a stop sign, and we know, too, that it is the rare driver who actually stops - most of us slowly glide through if we can do so; the ride is much more comfortable. We know which side of the road to drive on - when faced with a double-yellow line we don't have to think about how to react to it. We know that the amber light on the traffic signal heralds the red, so we'd better mash the gas so we don't have to wait the 40 seconds for the green light to come back; most of us seem to have forgotten that the amber light actually means "stop if you can do so safely". We are familiar with the flow of traffic and our place in it, we call upon our experience, and most of the time, things go well.
Problems arise when things don't go as we expect. A tire blows and our control of our car is reduced. The road surface changes drastically, and again our control is reduced. We have a green light, but due to a streetlight malfunction, we also have a red light - as does everyone else: we all proceed into the intersection and collide. But unless this happens, we tend to arrive safely at our destination, in spite of our efforts to the contrary.
Because we do actively undermine our safety. We drive too fast, we follow too close, we distract ourselves with coffee, donuts, cellphones, and reading directions. We never check the pressure on our tires. We don't read the owner's manual to our vehicles. Many of us can't be bothered to wear a seatbelt. We drive when we're impaired by drugs (typically ethanol, though OTC and prescription drugs, and other drugs are also sometimes to blame) or a lack of sleep. Because driving is easy, right?
Well, no. Or maybe more accurately, driving is easy, but driving safely is not.
This isn't necessarily our fault. We're used to our own scale, and we're designed to react to our own scale. If I weigh 140 lbs, then I'm used to moving 140 lbs around; I have a sense of how fast I can accelerate, and how fast I can stop, how tightly I can turn. If I want to pick up a heavy box, I know that the effort require to do so will relate directly to the mass/weight of that box - there's an intimate feedback that lets me know how much weight I'm dealing with, and thus how careful I need to be as I move that weight.
A small car, though, weighs about one ton. Large SUVs exceed four tons, and large trucks can weigh much more than that, but I can get those tons of machinery to move with less effort than it takes to walk - I just press on the accelerator. if I want to change my direction, I move my arm and twist a wheel, and I've probably got power steering in case that's too difficult. Stopping takes the push of a different pedal; that probably has power assist, too. The feedback is lost. The ease with which I can get the car to move belies the potential difficulty I will have in bringing it to a stop. So without meaning to, I drive too fast, follow too close. My success as a pedestrian complicates my job as a driver.
There is also the theory of risk tolerance, or risk homeostasis. According to this theory, we each have a degree of risk with which we are comfortable, though this varies between individuals. If our risk is reduced, we are willing or driven to take steps to raise the level of risk to the our level of comfort. For instance, if my car has antilock brakes, I am willing to drive the car harder and demand more of the braking system, and my likelihood of crashing remains the same. As our roads get safer, we drive faster. Similarly, safer cars yield higher speeds. I think there is something to this - armed with air bags, some drivers refuse to wear seatbelts (which is one of the more idiotic examples, as the airbag requires the seatbelt if it is to be effective, say nothing of the possibility of being hit multiple times in the same incident).
It is thus not surprising that some emergency workers have started to use the term motor vehicle collision (MVC) instead of motor vehicle accident (MVA). with all that we do to undermine our safety, they argue, a collision is waiting to happen, and is no accident. (In a similar vein, some medical practicioners are abandoning the term cerebrovascular accident (a term that includes strokes and transient ischemic attacks).)
More on this later - this post is getting to be too long.
Saturday, September 8, 2007
Speed limits don't work
I was raised to be a very concientious driver. My father, who did the bulk of the driving on any road trip, follows every law to the letter, never exceeds the speed limit (actually, he did once - it was late, and dark; he was a bit agitated because we had taken a wrong turn somewhere; and he exceeded the posted limit by three or four miles per hour - I could see the speedometer form my place in the back seat) He also makes full and complete stops at every stop sign. And as a starting driver I emulated this behavior. But, as is the case with most drivers, I started to relax a bit with time. I'm a little older now than when I was in college, and I suppose that's part of the reason why I don't drive as fast as I used to. The cost of gasoline is another - mileage plummets with excessive speed. But the road itself also plays a major role.
I realized this several months back while driving to the store. The road that I take most of the way starts out in a residential community, with a 30 mph limit, then opens up into a thinly-developed area. Here, the north- and south-bound lanes are separated by a grassy median and the lanes are wider; here the speed limit is 55 mph. For the most part, the road is straight in both areas. But the thing is this: people drive at about 40 or 45 for the whole distance. For the 30 mph zone this isn't a surprise - people seem to drive between 5 and 15 mph over the speed limit around here. But driving 40 in a 55 is not common around here in the absence of very heavy weather.
I shared this observation with someone - I now forget who, I'm afraid, and was asked in return "does it feel like a 55mph road?" It doesn't, of course. There may be a grassy median, and the lanes may be a bit wider than typical for residential areas, but it lacks the guard rails and other attributes of a parkway, far less an Interstate (did you know that Hawaii has an Interstate highways? Think about that. Interstate doesn't mean interstate.) Not long after, I found a (PDF) report of a study on, among other things, the relationship between posted speed limits and the actual speed of vehicles (see the section entitled "Operating Speed and Posted Speed Relationships", starting on page 46). Often, the 85th percentile (that is, the speed at or below which 85% of vehicles are travelling) was greater than the posted speed limit. This comes as no surprise. What was enlightening was that the relationship between the posted speed limit and the 85th percentile seemed to vary, in part, based on the type and setting of road: rural vs suburban& urban (S/U).
Rural situations tended to see a greater percentage of drivers traveling at or below the posted limit. This was especially so for two lane rural highways. S/U roads showed a lower percentage of vehicles at or below the (posted) limit, and showed a greater variation in the relationship between the 85th percentile and the posted limit. Something about the nature of the road influenced drivers in their choice of speed (yes, yes, there are plenty of variables that I'm ignoring - read the paper yourself and then come back and argue).
In a later section of the same paper ("Changes in Posted Speed Limit", p53), the effect of changing a speed limit is discussed. Of the sites evaluated, typically the initial speed limit was at the 20th percentile, while the new limit was raised to the 43rd percentile (of the original data). Following the change, the rate of driver compliance rose, suggesting that the change is speed limit influenced drivers - but that's not the case: average speeds, the standard deviation of the speed, and the 85th percentile generally changed by less then 2 mph each. Compliance rose not because the drivers followed the posted limit, but because the limit followed the drivers.
So, it would seem that there is something besides the speed limit that influences the speed of th typical vehicle, which brings me back to my drive to the market: the driver's experience of the road in the 30 mph section is very similar to the driver's experience in the 55 mph section. The grassy median is not a highway/parkway-exclusive feature; it is seen on boulevards as well. Further, it is not a standard highway feature - many highways lack a median, grassy or not (particularly in the city).
I also found the shared space philosophy (look it up on Wikipedia, and follow the references). It appears that removing roadway signs, traffic lights, cross walks, etc results, in some cases, in a reduction in the number of accidents. Personally, I think it has to do with drivers surrendering their responsibilities to the traffic control devices around them - removing the devices forces the drivers to assume personal responsibility. But whatever the case, this suggests that whatever effect speed limit signs have, it isn't a good one.
[boldface formatted 4 Oct 2007]
I realized this several months back while driving to the store. The road that I take most of the way starts out in a residential community, with a 30 mph limit, then opens up into a thinly-developed area. Here, the north- and south-bound lanes are separated by a grassy median and the lanes are wider; here the speed limit is 55 mph. For the most part, the road is straight in both areas. But the thing is this: people drive at about 40 or 45 for the whole distance. For the 30 mph zone this isn't a surprise - people seem to drive between 5 and 15 mph over the speed limit around here. But driving 40 in a 55 is not common around here in the absence of very heavy weather.
I shared this observation with someone - I now forget who, I'm afraid, and was asked in return "does it feel like a 55mph road?" It doesn't, of course. There may be a grassy median, and the lanes may be a bit wider than typical for residential areas, but it lacks the guard rails and other attributes of a parkway, far less an Interstate (did you know that Hawaii has an Interstate highways? Think about that. Interstate doesn't mean interstate.) Not long after, I found a (PDF) report of a study on, among other things, the relationship between posted speed limits and the actual speed of vehicles (see the section entitled "Operating Speed and Posted Speed Relationships", starting on page 46). Often, the 85th percentile (that is, the speed at or below which 85% of vehicles are travelling) was greater than the posted speed limit. This comes as no surprise. What was enlightening was that the relationship between the posted speed limit and the 85th percentile seemed to vary, in part, based on the type and setting of road: rural vs suburban& urban (S/U).
Rural situations tended to see a greater percentage of drivers traveling at or below the posted limit. This was especially so for two lane rural highways. S/U roads showed a lower percentage of vehicles at or below the (posted) limit, and showed a greater variation in the relationship between the 85th percentile and the posted limit. Something about the nature of the road influenced drivers in their choice of speed (yes, yes, there are plenty of variables that I'm ignoring - read the paper yourself and then come back and argue).
In a later section of the same paper ("Changes in Posted Speed Limit", p53), the effect of changing a speed limit is discussed. Of the sites evaluated, typically the initial speed limit was at the 20th percentile, while the new limit was raised to the 43rd percentile (of the original data). Following the change, the rate of driver compliance rose, suggesting that the change is speed limit influenced drivers - but that's not the case: average speeds, the standard deviation of the speed, and the 85th percentile generally changed by less then 2 mph each. Compliance rose not because the drivers followed the posted limit, but because the limit followed the drivers.
So, it would seem that there is something besides the speed limit that influences the speed of th typical vehicle, which brings me back to my drive to the market: the driver's experience of the road in the 30 mph section is very similar to the driver's experience in the 55 mph section. The grassy median is not a highway/parkway-exclusive feature; it is seen on boulevards as well. Further, it is not a standard highway feature - many highways lack a median, grassy or not (particularly in the city).
I also found the shared space philosophy (look it up on Wikipedia, and follow the references). It appears that removing roadway signs, traffic lights, cross walks, etc results, in some cases, in a reduction in the number of accidents. Personally, I think it has to do with drivers surrendering their responsibilities to the traffic control devices around them - removing the devices forces the drivers to assume personal responsibility. But whatever the case, this suggests that whatever effect speed limit signs have, it isn't a good one.
[boldface formatted 4 Oct 2007]
Friday, September 7, 2007
1) Lead cops on 100mph chase 2) Ram a cop car 3) Get rammed off road by cop car 4) Sue cops for excessive use of force
Makes sense to me.
On 30 April of this year, CNN reported on a decision by the Supreme Court concerning the (alleged - always alleged) actions of a Georgia teenager and the local police. It appears that the teen, who was driving with a suspended license, didn't want his car to be impounded. A cop had tried to pull him over for speeding. Instead of complying, the teen led police on what dashcam footage shows to be a > 100 mph case, crossing the double-yellow line to pass "about three dozen cars" (the article isn't clear if this was in one pass or several). Apparently, he also rammed a police car after it tried to block him into a parking lot that he had entered in his escape attempt. At this point the cop radios his supervisor, asking for permission to use "potentially deadly force" to stop the fleeing suspect. The supervisor assents, giving permission to use the PIT maneuver, but later (whether during the chase or after is not clear in the article) the officer says that the suspect is going too fast, and he (the officer) is worried about involving other drivers. So he rams the suspect's car, sending it off the road, injuring the suspect and leaving him a quadriplegic (there is a link for a video clip from the dash cam of one of the involved police cars, but the necessary plugin isn't free.). Later, the suspect sues the police for using excessive force.
I have to say, the teen has chutzpah.
Lower courts held that the teen had a right to sue (after all, this is AMERICA - I can sue you because I don't like the color of your shirt); the Supreme Court overruled this, 8-1, essentially dismissing he case. The argument for the dismissal was that the teen presented a real, severe, and immediate danger to the public; forcing him off of the road was in the public interest. The lone dissent stated the reverse: "I can only conclude that my colleagues were unduly frightened by two or three images on the [dashcam] tape" that played an important role in the police officer's defense. I guess that the roads and the drivers around Washington, D.C. are better than those around here: how is driving at > 100 mph on a two lane road, or crossing the double yellow line to pass about a dozen cars not dangerous, in a real and immediate sense, to anyone else who happens to be on that road with you?
Now, I'll admit that CNN doesn't comment on what the traffic was like at the time that the officer decided to ram the suspect's vehicle instead of using the PIT maneuver. It is possible that there were no other cars in sight, and that the officer could see enough of the road ahead to determine that there was no traffic that might get ensnared in a PIT maneuver, though I'll also repeat that the officer considered the PIT to be unacceptable at the speed of the suspect's vehicle. But at 100 mph you're traveling 100/60 = 1 and 2/3 miles every minute. If a vehicle is approaching you from the front at only 20 mph, then the you're getting 2 miles closer to that vehicle every minute. No doubt the roads in Georgia are different than the frost-battered ones of New York, but I rarely get the privilege of seeing even one mile ahead of me on the interstate, far less two miles ahead of me on a two lane road, and not considering the potential of vehicles entering from side streets or driveways. That's a lot of road for John Q. Public's vehicle to be hiding in. Isn't protecting the public part of what a police officer is supposed to be doing?
Finally, I am aware of the argument that the police could have broken off the chase. That's a discussion for another day. And I'm aware that being a paraplegic for life is tough punishment for refusing to pull over for a speeding ticket. Life isn't fair. But if we believe that our legal system should be fair, is it any more fair to force punishment on a police officer for actions that protected the public?
And don't even get me started about bad driving.
On 30 April of this year, CNN reported on a decision by the Supreme Court concerning the (alleged - always alleged) actions of a Georgia teenager and the local police. It appears that the teen, who was driving with a suspended license, didn't want his car to be impounded. A cop had tried to pull him over for speeding. Instead of complying, the teen led police on what dashcam footage shows to be a > 100 mph case, crossing the double-yellow line to pass "about three dozen cars" (the article isn't clear if this was in one pass or several). Apparently, he also rammed a police car after it tried to block him into a parking lot that he had entered in his escape attempt. At this point the cop radios his supervisor, asking for permission to use "potentially deadly force" to stop the fleeing suspect. The supervisor assents, giving permission to use the PIT maneuver, but later (whether during the chase or after is not clear in the article) the officer says that the suspect is going too fast, and he (the officer) is worried about involving other drivers. So he rams the suspect's car, sending it off the road, injuring the suspect and leaving him a quadriplegic (there is a link for a video clip from the dash cam of one of the involved police cars, but the necessary plugin isn't free.). Later, the suspect sues the police for using excessive force.
I have to say, the teen has chutzpah.
Lower courts held that the teen had a right to sue (after all, this is AMERICA - I can sue you because I don't like the color of your shirt); the Supreme Court overruled this, 8-1, essentially dismissing he case. The argument for the dismissal was that the teen presented a real, severe, and immediate danger to the public; forcing him off of the road was in the public interest. The lone dissent stated the reverse: "I can only conclude that my colleagues were unduly frightened by two or three images on the [dashcam] tape" that played an important role in the police officer's defense. I guess that the roads and the drivers around Washington, D.C. are better than those around here: how is driving at > 100 mph on a two lane road, or crossing the double yellow line to pass about a dozen cars not dangerous, in a real and immediate sense, to anyone else who happens to be on that road with you?
Now, I'll admit that CNN doesn't comment on what the traffic was like at the time that the officer decided to ram the suspect's vehicle instead of using the PIT maneuver. It is possible that there were no other cars in sight, and that the officer could see enough of the road ahead to determine that there was no traffic that might get ensnared in a PIT maneuver, though I'll also repeat that the officer considered the PIT to be unacceptable at the speed of the suspect's vehicle. But at 100 mph you're traveling 100/60 = 1 and 2/3 miles every minute. If a vehicle is approaching you from the front at only 20 mph, then the you're getting 2 miles closer to that vehicle every minute. No doubt the roads in Georgia are different than the frost-battered ones of New York, but I rarely get the privilege of seeing even one mile ahead of me on the interstate, far less two miles ahead of me on a two lane road, and not considering the potential of vehicles entering from side streets or driveways. That's a lot of road for John Q. Public's vehicle to be hiding in. Isn't protecting the public part of what a police officer is supposed to be doing?
Finally, I am aware of the argument that the police could have broken off the chase. That's a discussion for another day. And I'm aware that being a paraplegic for life is tough punishment for refusing to pull over for a speeding ticket. Life isn't fair. But if we believe that our legal system should be fair, is it any more fair to force punishment on a police officer for actions that protected the public?
And don't even get me started about bad driving.
Subscribe to:
Posts (Atom)
