What have you got to lose?
By Marc Mauss,
NYS Motorcycle Instructor and MSF RiderCoach
As an MSF Instructor, I teach that two seconds is the minimum safe following distance. More often than not, students only hear, "Two seconds is a safe following distance," and ignore the word "minimum".
I had an eye-opening experience yesterday, which proved that, in the case of following distances, more is better. I have made it a habit to use MSF-taught principles even when riding in my car.
I was on my way home from skiing, riding on the Long Island Expressway at about 25 mph in heavy traffic. MSF teaches that one of the ways to deal with tailgaters is to increase your following distance. I had just over 3 seconds between my car and the one in front of me because the guy behind me was practicing to be a hemorrhoid. (Yes, it really IS possible to leave that much distance on the LIE.)
Suddenly, I heard brakes screeching and saw the car in front of me go into a panic-stop. But not quickly enough - he hit the car in front of him. I applied my brakes quite hard, then realized that the hemorrhoid was about to hit me. I had plenty of room to ease off the brakes and still stop without hitting the guy in front of me, allowing the hemorrhoid to stop without hitting me.
But it gets better than that:
After changing lanes and going around the two cars in front of me, I realized that there was more to this than I had seen before. The three cars ahead of those two were also involved. Apparently the first car stopped and was creamed by car #2. Car #3 then hit #2. Car #4 was able to stop without hitting #3, but was hit by car #5 (who was right in front of me). I was able not only to stop in time to avoid hitting #5 (I was #6), but also had enough room to let car #7 (the hemorrhoid) stop before hitting me. Unfortunately for the hemorrhoid, he didn't have any extra room, so car #8 hit him.
I don't know how many vehicles were involved in all, but, because I left EXTRA space, I avoided the crash entirely.
In discussing this on a number of internet motorcycle mailing lists, I found that many people are averse to leaving a large (safe) following distance because of all the cars that cut in front of them. When I pointed out that this was just an ego thing, many replied that if they constantly allowed cars to cut in front of them, it would add HOURS to their trip. One list member pointed me to the answer to this by calculating how much time would actually be lost.
I haven't used his calculations here, but have slightly modified them.
Let's start with five assumptions:
1. Traffic is moving at a speed of 60 mph.
2. If you leave a two-second following distance, someone will cut in front of you every FIFTEEN seconds.
3. After someone cuts in, he/she rides half a second behind the car in front. (This is based on observation)
4. After someone cuts in, it takes you five seconds to return to your two-second following distance.
5. A car is twenty feet long.
OK. Here comes the mathematical part:
Sixty miles an hour is 88 feet per second.
At sixty miles an hour, a two-second following distance is 176 feet.
At sixty miles an hour, a half-second following distance is 44 feet.
Each vehicle that cuts in puts you an additional 44 feet (his/her following distance) plus 20 feet (vehicle length) behind the first car. This means that you lose 64 feet for each vehicle that cuts in.
A vehicle cuts in 15 seconds after the 5 seconds that it takes you to resume your following distance. That means 3 times a minute; you therefore lose 192 feet every minute.
If your trip is a half-hour long (30 miles at the 60 mph speed), you will lose a total of 30 X 192 feet in that half hour. So instead of going 30 miles, you will go 5760 feet less in that half hour. 5760 feet is 1.1 miles, so you will actually travel 28.9 miles in the half hour, making your speed 57.8 mph.
To go 30 miles at 57.8 mph takes 31 minutes and 8 seconds.
So, by leaving a two-second following distance and allowing a car to cut in EVERY FIFTEEN SECONDS, you actually lose only 1 minute and eight seconds. And that doesn't even take into account the fact that many of the cars that cut in soon cut back out.
Isn't it worth losing just over ONE MINUTE to be safe?