
A few sober notes on speed and accidents
Speeding is the most debated aspect of road safety. Traffic authorities hammer home speeding as one of the most important contributing factors to road crashes – whilst road users complain that many other aspects are neglected. A visitor to the Arrive Alive website requested responses to a questionnaire on speeding – and I believe it is important to share the responses from well known accident investigator Stan Bezuidenhout [IBF Investigations]
1. What is the relationship between speed and accidents?
National Government (Arrive Alive, etc) will tell you that “speed kills.” But, it must be kept in mind that the relationship “between speed and accidents” has a direct influence on the one element relating to what it actually means: time over distance. If a vehicle covers one meter per second, we typically describe this as “slow” while one covering 100 meters per second is described as “fast.” This, in turn influences a very important other element - the human factor. Whatever the unit of distance in a particular time frame, the limitation this introduces remains the processing speed of the human model. WE can only “think so fast.” When too much happens in too short a time, the human model fails to interpret, analyze and react to the stimulus. Add to this the simple fact that humans are typically very bad at judging time/space changes, then you will be aware that the relationship between speed and accidents is actually the function of the relationship between human processing speed and the rate at which the world changes. So - I would say that the relationship between speed and accidents is one and the same as the relationship between the processing speed of the human model and time/distance. To this effect, I would say that almost all accidents involving any human factor (speed, control, etc) is directly influenced by-, has a direct relationship to-, and directly influences the speed vs. accident hypotheses. So - in short - speed and accidents have a very, very strong relationship. Accident rates increase exponentially when speed is increased, since the human model and its ability to analyze, interpret and react to situations remains constant, while the time/distance analytical capacity diminishes as the time/distance element is increased.
2. What is the average speed at which most accidents occur?
In our experience (at more than 7,500 road traffic collision investigations) the typical “speed” at which an accident happens is no higher than 80Km/h. But, things ned to be brought into perspective again. This is like asking “at what age do people die.” It is very relative. We need to ask “at what age do people die after the age of 40″ in order to narrow the analysis. Also, we might include or exclude natural versus anomalous mortality. So - with accidents, it is no different. In cities, 80Km/h applies. But, again this is based on the (often false) reports received, since the TRUE speed of ALL accidents are not calculated, recorded, analyzed or reconstructed. So - we are left with a very small percentage of accidents, where the actual speed is known. Therefore, it is currently impossible to answer this with any degree of accuracy. In our experience, accidents in town happen at 60Km/h, on minor highways at 80Km/h and on national roads at 120Km/h (according to the larger percentage information supplied by the drivers). But we know this not to be true, since few people admit their true speed if they think it is going to expose them to legal liabilities. People lie - therefore, we cannot trust the results of the analysis - if any is ever done.
3. In what conditions do the most accidents happen?
This is a question that would be best asked of a statistical model, such as the one contained in the national accident information (eNaTis) system.
The Road Traffic Management Corporation might have this data. In spite of this, we would simply need to ask what weather is the most prevalent in South Africa. In Canada, it would be in snow, in certain parts. In the Namib desert, in sun-light. The appropriate question would be “under what weather conditions does the greatest deviation from the norm occur.” In this case, the answer would be “at night, and in rain.”
4. What percentage of accidents is alcohol-related?
In our experience, at more than 7,500 accident scenes (as stated), less than 10%. Do keep in mind that alcohol related accidents hardly ever occur during the week (office hours) when most vehicles are on the roads. Also, there are actually a very low frequency of accidents occurring on our national roads, that involve intoxication. People do not typically drink before driving from Cape Town to Johannesburg. But - they do drink on Friday and Saturday nights, then commute (a relatively short distance) back home.
This is when and where the higher percentage of drunken driver accidents occur. There is also an increase over the December holidays, and during periods when work parties, matric farewells or rugby celebrations take place.
5. What time of day do most accidents occur?
Again - a question for the RTMC. Although - commuter-cycles are most likely to be the higher accident statistic times, when people commute to-and from work. Just listen to any traffic report, on any radio station, then you will be well informed in “real-world” terms.
6. What reasoning is there behind this?
Most traffic is on the road during commuter cycles, people are impatient to get to work, late for work, or tired and hurrying home.
7. In most accidents, is the cause more often human error or vehicle?
Most definitely human error. Actual Vehicle Mechanical Failure accounts for far less than 5% of all accidents - world-wide.
8. What went wrong (with the vehicle or driving) in most cases?
Human error. The inability for the human model to appropriately interpret the set of dangers contained in a particular situation. This typically involved a person making a decision that results in a mis-interpretation of the true situation, and thereby over-stepping the boundaries of safety.
There is also a great problem in South Africa with vigilantism, and the results are starting to manifest as the occurrence of head-on collisions where there was adequate time, space and distance for evasion and prevention- yet people still run into each other.
9. What percentage of accidents is fatal?
RTMC will answer this, but it needs to be kept in mind that South African statistics are very inaccurate, at best. Did you know - as an example - that if someone died more than seven days after an accident, as a result of his or her actual injuries in an accident (let’s say doctors are waiting for a family member to approve them turning off life support units), that this death is NOT included in the national statistic?
10. How many accidents occur daily in South Africa (rough estimate)?
There are more than 700,000 accidents per year in SA. Again the RTMC would have better figures…
Visit the Arrive Alive Road Safety website for more information on road safety and accidents.
Recent Comments