Just a Few Miles Over the Speed Limit — Is it Dangerous or Acceptable?

Once a person has been driving for a few years, and maybe had no crashes, it’s okay to go a few miles an hour over the posted speed limit, right?  And the police don’t give out tickets if you’re doing just 35 mph in a 30 limit or 45 in a 40 limit, so it’s got to be safe, yeh?

Many people try to justify a bit of extra speed like this with their opinion that it’s safe and of no consequence, or they are frankly just oblivious to it because “everybody else does the same all the time,” but sadly — in fact tragically — these myths are the opposite of the truth.

A major part of the problem lies in the laws of physics — the only laws, so the old joke goes, that nobody can break — so if you don’t like what follows, blame Einstein and Newton and all of their pals.

A key fact is that the faster an object is moving, the harder it is to stop it.  But this is where those rules of physics come in.  A normal, non-scientific person would assume that if something is going twice as fast now as it was say a minute ago, it will be twice as hard to stop it, right?  But it doesn’t work like that.  At twice the speed, an object is much more than twice as hard to stop and as a rough rule-of-thumb a vehicle takes about four times as far to stop under braking if its speed has been doubled.

The other problem involves a driver’s best reaction time.  Straight away, though, here’s another sad fact:  Most drivers don’t concentrate properly on their driving so very few can use their “best” reactions in an emergency.  So whether a person has good, medium or bad reactions, they will take the same time  as they usually do to react in any risky situation that they were not expecting to occur, and if a vehicle is travelling at twice its previous speed it will obviously cover twice the distance while the driver is in the process of reacting, so a lot of extra ground has been lost and there is now that much less time and distance in which to stop before hitting the thing up ahead that has caused the driver to brake.

Most people can do well on an actual test of reaction time.  Someone says something like “press the button each time the light comes on,” and you do.  But the problem is that you know that the light is going to come on and so you are ready, with your finger on the button and muscles tensed.  But real life, and in particular driving, are not like that.  Drivers are typically far too complacent (e.g. “I’ve been driving for thirty years and never had a crash.” Or “I’ve driven this road a thousand times; I know every bump and twist.”)

And virtually all drivers are distracted, too.  Yes, far too many are crazy enough to talk on cell phones — even hands-free phone conversations significantly increase the risk of a serious crash but it’s not possible to enforce this so no law enforcement agencies have tried to do so — and others even text while driving, which is a form of homicidal or suicidal lunacy.  But these aren’t the only issues:  Anybody driving while thinking about anything other than their driving at any moment is a distracted driver; there’s no getting away from that fact, and we ALL do it.  A key difference between unsafe drivers and safer drivers is that the safer ones think only about their driving for a much larger proportion of the time, and that takes effort.  But nobody is a robot.  Nobody can concentrate at the 100 percent level for 100 percent of the time, especially on longer journeys.

So now, back to the few miles an hour over the posted speed limit:  That’s only a few MPH, right; not double the speed?  But lets see the effect.

Here’s a relatively old video showing exactly what can happen when a driver is doing 35mph in a 30mph limit.  The age of the video is irrelevant because the physics of the matter will never change. Even as better braking technology has trimmed some feet off stopping distances over the years, that still has not prevented the same effect happening; it just takes place at slightly different distances.

The next video shows a very different way of looking at the same problem, but as the speeds used are given in kilometres, here’s a conversion list for American and British readers:

  • 65 km/h = 40.6 mph
  • 60 km/h = 37.5 mph
  • 32 km/h = 20 mph
  • . 5 km/h = . 3 mph


So just a tiny three miles per hour difference in the initial speeds made a life-threatening 17mph difference in impact speeds.  If that doesn’t convince you, nothing will!

Finally, if you are thinking about swerving as an alternative to braking to try to avoid a crash, please don’t forget that while swerving is sometimes successful on racetracks, where everyone is ultra-alert and all travelling in one direction (although it can still fail spectacularly, too), and it might be great fun to practice skid recovery or evasive swerving on abandoned runways and empty parking lots,  the fact is that on real roads there are often vehicles coming the other way.  Do you want to hit one and die?  Trees and ditches can easily kill you, too.  And then there can be pedestrians, bicyclists or motorcyclists nearby.  Do you want to kill them (and then pretend to the officer that it was somehow an unavoidable “accident” rather than a dangerous choice of your own speed)?

Take a look at the Golden Rule of Safe Driving.

If this article sounds as though I’m preaching at readers or lecturing you, I apologize, but as a retired traffic patrol police officer who has attended too many fatal and serious-injury crashes, and also had to tell too many devastated loved ones that their husband, wife, daddy, mommy, brother, sister, son or daughter is never coming home again, then — believe me — I really hope that you will take the above facts to heart and make sure that neither your own family nor anyone else’s will ever have to hear that news all because you were doing a few miles an hour over the speed limit.

It happens every day without fail!  About 30 out of the average 100-plus highway deaths every single day in the USA involve someone driving over the posted speed limit or at a speed that was inappropriately too fast for the circumstances, even if that was within the limit.



The State With the Deadliest Traffic in America Admits its High-Speed Streets Have to Change

Linked here is is a very well-written post from StreetsblogUSA, and in huge contrast to almost everything written in the USA about traffic safety, it starts off very responsibly and accurately, with:

In the last few years, the traffic fatality rate in America has risen alarmingly high, wiping out a decade of progress and widening what was already an enormous gap between the U.S. and peer nations like the UK, Japan, and Germany…”

Photograph of the intersection between Pennsylvania Ave. and 16th Street, Miami Beach, Florida.
Pennsylvania Ave. and 16th Street, Miami Beach, Florida. Photo: Wiki Commons

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