Posts Tagged 2 Second Rule

Is The 2-Second Rule Good Enough?

How long does it take to stop your car – if the car in front of you stops on a dime?  The answer is   …   it depends.

 

First, our brains need to compute that the car has stopped and that we need to stop right away, or we’ll crash into them.  That might take a second.  It might take longer if we’re having a conversation or the kids are yelling in the back of the car.  Or, we’re eating or talking on our phones.  Sometimes, we might be daydreaming about a problem that we have and that we need to solve.

 

Visual reminder to start counting at "Zero" - instead of starting at "One", when counting to "Three".

It might take two or three seconds to realize that we’d better stop right away.  Race car drivers are considered perfect if they can stop within a half a second.  None of us are perfect and we do have those distractions that I just mentioned.

 

Why don’t we have more rear-end crashes – then?

 

Most of the time the car in front of us can’t stop immediately because it has its own momentum and that gives us a second or two to notice that they put their brakes on and we’d better stop, too.

 

There are exceptions, of course.  Maybe they weren’t paying attention and a semi-truck stopped suddenly and they didn’t notice.  In that case, they would smash into the Semi and that wouldn’t give YOU time to stop, either.  This is when a driver gets seriously injured.  Pay attention.

 

One time, I was a passenger in a car and the driver WAS paying attention. But, it was twilight and there was a truck in front of him.  He had a bunch of wooden pallets in the back of the truck and one of the pallets suddenly went flying off the truck – onto the road.  The driver responded quickly – but, not quickly enough to avoid an accident.

 

The underbelly of his car suffered quite a bit of damage.  He didn’t have total body coverage and it cost several thousand to get his car fixed.  At least no one in the vehicle suffered any physical injuries.


The main problem is that if the car in front of you brakes heavily, the driver behind him might not even have time to react before hitting it.

 

Keep the following in mind:

  • Motorcycles take longer to stop than cars do.
  • Trucks take even longer to stop than do either motorcycles or cars.
  • Cars that have worn out tires take longer to stop. Different things affect the stop distance – such as, the type of tire, how it’s inflated, the suspension of the tires and how they are balanced.
  • If you have anti-lock brakes, (ABS), then you’re in a better situation than someone that does not have anti-lock brakes.
  • Older drivers can have reaction times that exceed 1.5 seconds.

 

Is the 2 second rule enough time – to avoid a collision?

 

The total stopping distance consists of your thinking distance and your braking distance. Under ideal conditions, you’d have one second to realize that you need to stop and one second to bring the auto to a stop, or to take an evasive action.  Technically, two seconds is not enough when you factor in reaction times.

 

When should you use the four-second rule?

 

Increase your following distance to four seconds per car length, if it’s wet or icy out.  That will give you more time and more room to stop properly. 

 


We Will Fight For You!


Call the Law Office of Gerald Fugit at 432-301-9252.

Only a Fool Follows the 2-Second Rule

What is the two-second rule of driving?

 

In order to adequately stop in time to not smash into the car in front of you in traffic, you need to keep a minimum of a two second ‘space cushion’ of stopping distance between you and the car ahead of you – at 30 mph or less.

 

To find this distance while driving – eyeball some object on the side of the road, like a billboard sign.  After the car ahead of you passes the object, count two seconds. If you pass the object within two seconds, you’re driving too close to the car in front of you.  You’ll need to remember to pay attention during these two-second calculations to make sure that other roadside objects, don’t come out of nowhere.Diagram that shows how to measure the stopping distance between your car and the car in front of you.

Credit: https://sites.google.com/site/johnparsonsadi/2-second-rule

The two-second rule is not sufficient for all speeds. The two seconds between cars is only relevant for cars at the lower speeds. You’ll need a much longer stopping distance when you’re driving faster.

 

The calculation for the time needed between two cars to allow the trailing car enough distance to come to a complete stop before hitting the leading car that had to stop immediately – is as follows:

 

Given a braking distance of 57 feet, (according to the Iowa Department of Transportation), when traveling at 30 miles per hour (30 mph = 44 feet/second), you need to have 1.3 seconds between you and the car ahead of you. So, you’ll need 57 feet in order to stop 44 feet/second=1.3 seconds.

 

But, our brains need time to process the information, decide to brake and then, to signal our feet to slam on the brakes. Using an average reaction time of 0.0000000000475, or 1.5 seconds, (from by the Iowa Department of Transportation), the total time needed to stop is: 1.3 seconds (braking time) + 1.5 seconds (reaction time)=2.8 seconds total.

 

 

At 60 mph, the time needed between vehicles comes out to over four seconds.

 

 

So why doesn’t the two-second rule work?  SCIENCE. The reason is that the energy required to stop is dependent on the force of friction (F) over a distance (x) (W = FΔx) and is also equal to the change in kinetic energy, which is dependent on the mass (m) and speed (v) (ΔKE = ½mv2), which means that FΔx=12mv2.

Credit: https://www.cunesower.com/everyday-science-two-second-rule/

 

If we double the speed (v), the distance (x) is quadrupled (22 = 4), meaning more stopping distance is necessary at high speeds than predicted by the two-seconds rule. Here’s a video that might help:

 

 

A good approximation would be to add a second to your reaction speed (1.5 seconds), between cars for every 20 mph that you’re driving. That works out to about three seconds for city traffic and four to five seconds of stopping distance for highway traffic. Apply a couple more seconds between cars in order to safely stop if the road is wet or slippery.

 

If another driver was following too close to you and you’ve been injured as a result of their actions, you may be entitled to compensation.  It always depends on circumstances – but, your damages might include:

  • Reimbursement for your medical expenses,
  • Repair or replacement of your vehicle,
  • Compensation for pain and suffering,
  • Compensation for lost income.

 


We Will Fight For You!


Call the Law Office of Gerald Fugit at 432-301-9252.