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#1
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"Cover your break"?
I've heard this advice alot. My question is, why cover your break at
an intersection- what use does it do? Suppose I enter an intersection with a green light at 30 mph (following the usually defensive driving advice to slow down a bit), and I just happen to see that pickup comming at me at 40 mph, running the red light. What good will slamming on the brake do? Will my car really stop that fast? Wouldn't it be better to slam on the accelerator (assuming my car could accelerate that quickly?) What's the proper "defensive driving" technique in that situation that would make covering ones brake a good thing? I suppose- maybe, if you stopped fast enough the pickup might catch you on the front end instead of the midsection of the car. Any clues? |
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#2
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Magnulus wrote:
> I've heard this advice alot. My question is, why cover your break at > an intersection- what use does it do? > > Suppose I enter an intersection with a green light at 30 mph (following > the usually defensive driving advice to slow down a bit), and I just > happen > to see that pickup comming at me at 40 mph, running the red light. What > good will slamming on the brake do? Will my car really stop that fast? > Wouldn't it be better to slam on the accelerator (assuming my car could > accelerate that quickly?) > > What's the proper "defensive driving" technique in that situation that > would make covering ones brake a good thing? I suppose- maybe, if you > stopped fast enough the pickup might catch you on the front end instead of > the midsection of the car. Any clues? Slowing down makes it easier to turn (i.e. swerve out of someone's way) without spinning out/throwing your passengers into the doors. |
#3
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Magnulus wrote:
> I've heard this advice alot. My question is, why cover your break at > an intersection- what use does it do? What's a break? |
#4
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On 2/4/2005 11:42 AM, Arif Khokar wrote:
> Magnulus wrote: > >> I've heard this advice alot. My question is, why cover your >> break at >> an intersection- what use does it do? > > > What's a break? That thing you're suppose to cover at an intersection. Duh. -- ~/Garth |"I believe that it is better to tell the truth than a lie. Almgren | I believe it is better to be free than to be a slave. ******* | And I believe it is better to know than to be ignorant." for secure mail info) --H.L. Mencken (1880-1956) |
#5
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A writer asks if they should "cover the brake" when approaching an
intersection. Sounds like a bad intersection design. If you don't have visibility to see a vehicle approaching on the cross road to make your go/no go decision then the posted speed is too high. Or your scan pattern is faulty. Green, to me, means the driver has to "clear the intersection". The driver has to visually sweep the approaching roads to avoid crashes. A signal implies visibility of cross traffic. Otherwise the intersection should be controlled by two way or four way stop signs. Or better yet, a roundabout or a flyover. Speeds are set at the 85th percentile of observed speeds. Drivers adjust speeds for congestion, but not for sight stopping distance. Or consent relative bearing crashes. Yellow signs versus white signs. This intersection sounds like it needs some engineering corrections. To me, covering your brake means to put your foot on the brake and even actuate it to the point of lighting the stop lamp, but not actually forcing the pads onto the rotors. This saves maybe 200 milliseconds, about one half car length at 40 MPH. If you are trying to control your car to the nearest half car length at 30 MPH, you are way over the control limit of steering or braking. You are very likely to induce steering oscillation and overturn your car if you try to steer fast enough to miss the approaching car. At thirty MPH, you should allow a cushion of at least three car lengths. That includes the approaches from the sides. Give yourself more cushion. One car length for each ten MPH up to 30 MPH then two car lengths for each ten MPH over 30 MPH. Approach speeds are nearly equal in your example. Thirty and forty MPH. Angle of constant relative bearing, about 50 degrees for the slower car and 40 degrees for the faster car. The driver of the slower car MIGHT notice the faster car if he moves his head and eyes. Neither driver will see the other car if the cars remain on a constant relative bearing and the drivers don't move their head and eyes. Or if there are shrubs, trees or buildings in the line of sight. If you are covering the brake in anticipation of the light turning red, you need some practice on solving the dilemma zone. There is a segment of road on the approach to a signal where you can either proceed before the light turns red or stop safely, even of you still have some yellow. At some point in the approach to the signal, you need enough confidence to stop looking at the light. Not because you know you are going to make the green, but to scan for other vehicles. If you concentrate on the light all the way to the cross bar, you will not see other traffic. For most intersections, the solid lane divider gives a visual clue. If you are at the speed limit to about 5 MPH below and the light is still green when you reach the solid line, your car will enter the intersection before the light turns red. Don't speed up, don't slow down. Look for cross traffic. Next time you are a passenger going through that intersection, notice how much of the cross road you can see. Can you see the cross road through the side windows? Or is anything beyond the A pillar blocked by shrubs or signs? |
#6
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> wrote in message oups.com... > Speeds are set at the 85th percentile of observed speeds. They should be, but aren't always. |
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