Safe Speed Forums

(my emboldening)

But if it's dangerous, which I think it must be by definition, then it must also be rare, simply because inappropriate speed crashes are rare.

32 million licenced drivers, 214,000 injury crashes of which 12% have 'excessive speed' as a contributory factor.

So causing an excessive speed injury crash is a once in 1,250 year experience for the average licenced driver. (assuming that one driver causes each crash (and reality is less than that because some crashes are caused by folk not driving).)

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

I think the superset might best be ... {vehicle operators' activites }

Other similar groups of sets worthy of [yes, sorry Starfin - replace that phrase with what you like at this stasge] inclusion might be

{driving while over the drink drive limit}
{driving while drunk}

{provisional licensed drivers}
{limited experienced drivers}
{experienced drivers}
{unlicensed drivers}

{high power/weight (say 0 - 60 in less than 8 sec or > 140 mph top speed)}
{inbetween}
{low power/weight (under the ton/over 20 sec to 60)}

If we do that it's huge. But the first division is interesting. {risky activities} {non-risky activities} But according to my thinking so far the interesting {risky activities} set has too many subsets to make an easy to understand diagram.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

no, not true. Driving between 2 rows of parked cars at 30+mph is by no means safe but 99% of the time nothing bad is going to happen. It's only when something or someone decides to run in front of you (amongst other things) that you're going to get into trouble. The problem is you don't know when that's going to happen. Fortunately for the idiots out there, it's that event that's rare.
Same idea goes for tailgating. Most of the time, no problem at all. This is why people do it. "I've been driving for 40 years and never had an accident so I must be a good driver"... or just plain lucky.

As I read the original diagram, it makes sense and makes a good point in itself.

I interpreted it as...

you can be speeding in the eyes of the law and not be inappropriately speeding.

you can be driving at the legal limit and be driving at an inappropriate (dangerous) speed.

Which makes sense in itself.

I don't think it needs to be overcomplicated by other factors, just a lead-in to them.

e.g. "If we can see clearly that exceeding the speed limit is not the sole (or even main) factor...what other factors are there?" And then go on to another one.

Keep it simple, that's what I say.

OK. Interesting enough. I stand by my assessment.

If you look at the entire road network, I think you would find that >50% of speeds are illegal and <1% of speeds are inappropriate. The estimates might be a bit messed up where there's congestion.

I agree that in some urban situations inappropriate speeds seem common, but even then it's probably only 1 in 10 or 1 in 20 vehicles.

I don't agree that the critical events that lead to crashes are rare by the same yardstick. I think there are something like 30 million of them a year. with ~27million of them mitigated to near misses, and 3 million damage only crashes. However that's only one critical event per year per licenced driver - which by other yardsticks is indeed rare.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

In some ways my {speed} superset was tongue in cheek - in the sense {speed} was mean't to equate to {moving vehicles}

that depends where you are. Around here at times it's more like 1 in 2 or 3.


given the number of people I see driving at inappropriate speeds around here and the relative lack of accidents I can only conclude that the critical events, in suburbia, are indeed rare.
If you're ever near Beckenham please let me know as I'd like you to pop around and witness for yourself some of the sheer stupidty that passes for driving in these parts.

Clearly (Johnsher's point) we cannot say that the speed of any particular vehicle at any particular time is not inappropriate merely because it does not result in a crash, or a near miss.

I think it is likely that inappropriate speed is quite common or very common but, at the same time, is it not quite likely that inappropriate speed within the posted limit is more common than inappropriate speed above the posted limit? Why? Because although ~60% of vehicles (in 30/40 limits) may be speeding at a given point of measurement (used to collect the data), it is more likely that the overwhelming majority of vehicles, at all possible points of measurement, are not exceeding the posted limit (I'm talking about urban situations here - out on the open road, and on motorways, the picture is different).

It seems to me that the aspect of driving that many/most drivers fail to appreciate is that, on public raods, we must drive at a speed that allows a reasonable margin for safety (time to react) and that our time to react is determined by space (relative to our speed). If we wish to increase speed, we need more space; if less space becomes available, and cannot be created, we have to reduce speed to maintain the safety margin.

This observation, if correct, supports the conclusion that reducing speed limits unnecessarily, and enforcing speed limits indiscriminately, is simply missing the point of what's needed to improve road safety generally. We need to improve driver training so that drivers are able to make these assessments of safe/appropriate speed for themselves - we can't drive for them.

When I look at the numbers of potential road conflicts that must be avoided each day I cannot believe that inappropriate speed is commonplace. This ties in well with 85th percentile principles which tell us that the great majority of drivers do not routinely drive too fast. And the small percentage of crashes (12%) with 'excessive speed' assigned as a contributory factor provides corroboration.

I've been exchanging PMs with Johnsher and he's agreed to try and video one of the bad places he's been describing. I'm hoping that we can make some objective estimates of inappropriate speeds from the video and perhaps find some resolution on the point.

Whatever the proportion of inappropriate speed there might be on the road network, I believe it is too high and can only be sustainably improved by 'intelligent' messages (skills, attitudes, responsibilities). Local schemes have a much smaller part to play - in fact I'm pretty confident that they have already been overplayed.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

We may be talking about differences of degree of inappropriateness here. I would agree that the vast majority of drivers do handle speed appropriately most of the time. Nevertheless, I also believe that possibly an equal number of drivers fail to recognise that their choice of speed, in certain conditions, has shaved their safety margin to next to nothing. Perhaps an example will help.

In my village, the main shopping street is constructed on a hill with shops, pavement and parallel parking on one side. On the other side is rough ground that banks steeply down to the road. There is no pavement or pedestrian walkway on that side. The road is just wide enough for a row of parked cars plus two-way traffic but, if there are parked cars (which there will be during business hours), a vehicle running downhill has to pass very close to the parked cars if there is any traffic coming the other way.

Proceeding up the hill, with no pedestrians on the nearside (there is nowhere for them to walk), it is perfectly reasonable to drive at 25-30 mph, unless there is an obstruction, because of the safety space provided by the opposite lane. Proceeding downhill is completely different (unless there is no opposing traffic in which case one can use the opposite lane) because one is forced to drive so close to the parked cars that slowing to 10-15 mph or less is (imo) essential to allow for hazards such as a driver carelessly opening a car door. However, I frequently observe vehicles driving down this hill (with traffic proceeding uphill at the same time) at a speed which is legal but, imo, inappropriate, simply because it leaves little or no safety margin.

To be fair, I don't actually know of any accidents or pedestrian casualties on this road so it could be argued that the general level of traffic speeds is not inappropriate and, perhaps, that my view of a 'safe speed' is over cautious. I would say that 1 in 10 vehicles travelling (imo) 'too fast' is possibly a fair proportion but, if I am right, that is still a significant incidence of inappropriate speed. That also supports my instinct that there is a higher incidence of inappropriate speed where the speed is within the speed limit than there is where the speed is above the limit.

Let me ask you a question. Imagine that you are sitting in the passenger seat of every car driving in a busy urban situation, perhaps like the one I've described, trying to pass on your accumulated experience and knowledge of safe driving behaviour. How often would you be saying to the driver "A little bit fast just there"?

[Edit]
I should like to add, Paul, that I freely and gratefully acknowledge that my appreciation of these (and other) nuances of defensive driving has come about only because of the time that I have spent reading your website and participating in discussions on these boards. I believe there are other members who are in the same position as me and, regardless of the big picture, you should deservedly be proud of the direct contribution you have made to the quality of understanding and implementation of safe driving practice even of those relatively few of us who have been directly inspired to examine and (hopefully) improve our driving techniques.

My thoughts exactly.



Good question. (and not least because it gets the answer you wanted! )

CONSTANTLY!

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

I can think of several juntions near me where the perception of what was appropriate would vary dramatically depending on wether you were on the major road or trying to join it from a side road. These junctions are all clearly visible from the main road and so 30mph feels too slow but from the minor roads you can not easily see far enough to give sufficient time if anything is approaching much faster than 30mph. The point is that unless drivers on the main road had tried to enter from those side roads they would have no idea how difficult it was.

Hi Paul,
I love the visual presentation of the facts like this. A lot of people cannot relate to text or graphs. Have you a final objective for the diagrams or are you exploring and seeing where it goes ? Some ideas :-

1/ Using the number of fatalities caused by the groups/sets. You do not need to cover all sets/subsets to compare say :-

Fatalities saved by cameras 20 ( using 4/5 of 100 not sure if this is exactly O.K.) ( not sure to admit cameras save any lives )
Fatalities caused by drunks/drugs 560 ( latest casualty figures )

Visual representation of cause of fatalities with speed as the seventh and smallest target. Not only is it the smallest target - hardest to hit. It also gives the lowest score in terms of saving lives. And as we Know often missed with lots of collateral damage.


P.S. What is the latest best guess using the dodgy data of the 4th year report of fatality reduction due to cameras ?

Richard

Where's the <blush> smiley when you need it?

Seriously, Tim, kind of you to say so, thanks.

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety