S.P.E.E.D. kills
Draft. This page tries to present the major causes of road traffic accidents in an amusing and memorable way.

(We hope to extend it considerably in the next few days. Comments welcome)

The real killers on the road are
  • Sleep
  • Poor concentration
  • Errors of judgement
  • Errors of observation
  • Dangerous attitudes

It's well know that there are plenty of accidents where drivers simply fall asleep. These accidents are frequently serious because sleeping drivers don't brake before impact.

Lowering vehicle speeds promotes sleepy driving. Lower speeds are less mentally stimulating and journeys take longer. 

Poor concentration

Poor concentration causes all those crashes where a driver fails to pay proper attention to the situation ahead. Sometimes the driver might be distracted by a passenger or a mobile phone call, sometimes the driver may simply be thinking about something else. Safe driving requires a very high degree of concentration because the situation ahead can change at any instant. When the situation ahead does change, the driver must notice the change, decide on a course of action, and implement the course of action often all within a single second.

Where concentration is poor, it's all too easy to forget to make a mirror check...

Lowering vehicle speeds can promote poor concentration.

Errors of judgement

A car drives into a bend far too fast. The laws of physics mean that the bend simply cannot be negotiated at this speed and an accident ensues. What really has happened here?

We could say the driver was going too fast; simple as that. But it's more useful and informative to consider why the driver was going too fast. He may have reckless disregard for road traffic laws and his fellow man, but we can almost always assume that he had planned to negotiate the bend. Entering a bend too fast is an error of judgement.

A car pulls out to overtake. The driver mistakenly considers that he had time to complete his overtaking manoeuvre before the end of the clear straight section of road ahead. He can't and at the wrong moment an oncoming vehicle appears. Unsafe overtaking is usually an error of judgement.

Other errors of judgement include:

  • Too fast in fog
  • Gap not large enough for vehicle
  • Gap in traffic closed before arrival
  • Failure to leave a "time to react" space
  • Exceeding safe speed
  • Exceeding available grip
Errors of observation

Sorry mate I didn't see you. Many road accidents are caused by failure to observe another vehicle or road user until it is too late to avoid a crash. This differs from poor concentration (which sometimes causes not looking), in that in these cases driver usually look but do not see.

Countless thousands of motorcyclists have been injured by car drivers simply driving into their path. Sometimes this is because the motorcyclist was behind the car's windscreen pillar at the moment when the car driver glanced once to see if the road was clear. There is also a blind spot in the human eye where the optic nerve joins the retina and sometimes the unseen road user might have been in the blind spot when the glance check was made. (see this web page)

It would be easy to alert drivers to these potential problems, but precious little effort is made and few drivers know about them. The solution is that a glance check is usually insufficient, and experienced drivers use a longer period of observation. Better yet is to make several distinct and separate observations. SafeSpeed visitor Martin Nicholas put it like this: "I was taught, and have found to be true, that two short looks beat one long look. Partly to allow your eyes to return to the view ahead and partly because you get a chance to confirm or disprove what you thought was happening on your first look. For example, judging 'speed of approach' is easier with two half-second looks one second apart than with a single one second look."

There is also a distraction effect. Something distant and highly visible may distract the eye from observing something closer but less highly visible. You've probably had this when planning to overtake in poorer light, you've seen and planned for the distant car showing dipped headlights, only to later notice a nearer dark green car without lights. If you haven't yet, you probably will. (owners of dark coloured cars take note...)

Sometimes a driver will think he has seen where the road goes and plan to drive ahead. He might find out too late that he failed to observe the road ahead properly and now has no time left to adjust his course or speed.

Inexperienced drivers are noticeably weaker at good observation. 

Dangerous attitudes

A stolen car speeds through a red light. An old man continues to drive with increasingly poor eyesight. A young person neglects essential tyre and brake maintenance. A boy racer thinks nothing of forcing others vehicles to brake or swerve.

Safe driving only comes after a responsible attitude and a calm approach. You know it makes sense! 

Other causes

Mechanical failure
Driver inexperience
Unexpected loss of control
Close following


Very few real world accidents are caused by speed. The vast majority are caused by s.p.e.e.d. Although the concept behind this page is amusing the subject and the claims are deadly serious. These are the real major causes of modern road accidents and can all be addressed with training, publicity and efforts to foster good attitude in drivers. They cannot be addressed with more speed cameras.


Comments on the above are welcome. If there is a demand we will create a comments page or add to the text on this page. We will be delighted to publish all suitable emails including those whose content we disagree with. Email comment.

The contents of this page are original and copyright safespeed and Paul Smith 2002. Do not reproduce without permission. First Published 24th August 2002.