Safe Speed Forums

http://www.ayrshore.com/crash/crash.htm

and BBC news story of the crash:

http://news.bbc.co.uk/1/hi/scotland/gla ... 071980.stm

I'd say not f*cking looking before turning may have caused the crash.

The author of the ayrshore web page has a point, I'm afraid to say. The SPECS system has been trumpeted as a success using the usual RTTM benefit illusion stats as justification. A fiscally motivated solution to a problem that really requires better road engineering.

Also, the side effect of perceiving the flow of traffic to be always slower as a result of the presence of average speed cameras over a long distance is a fair assumption!

Another side effect that needs proper investigating!!

It could be that the unmarked could have been ‘doing a Milton’ – driving at very high speeds without the use of sirens, or at least the strobes, to indicate to other road users that their manner of driving could be so, contributing or causing the 4x4 driver to misjudge the situation.

IMO: linking the SPECS to this is a bit tenuous, but:
"The officers were on duty at the time, responding to a nearby road crash."..... on the SPECS enforced A77 ?


Unrelated:
"Ayrshire Central MP Brian Donohoe said he had been campaigning to get junctions on the road converted into ones with bridges for safety reasons.
He said work should have started by now...."
And if this system cuts casualties will all credit go to the camera system - as usual?

Of course. The A77 safety group has a number of engineering measures planned. You can be fairly certain that claims of camera success won't mention them at all.

_________________
Less Kodak, more Kojak.
In times of deceit, telling the truth is a revolutionary act.

I remember these cheating b*****ds. Their homepage use to say "the SPECS system is one of a range of measures carried out to make the roads safer" yet they never stated the benefits from these other measures, they only trumpeted the cameras. I pointed this out on their forum. A week later the page had that sentence removed and the forums had been 'pruned' - by which I mean completely deleted, all gone!



edit: I just logged back in, looks like there's never been a subsequent prune

Time to remind them of their folly

The traffic incident they were attending was on Tarbolton Road, Dundonald - just a few miles from the NEXT junction from the one the collision happened at.

I'm not laying the blame on the cameras, but we all know that there's not really such a thing as an 'accident' - just a series of mistakes, faults or events that happen in a chain that causes an incident - some of these could have changed the course of things.

IF there had been no SPECS, the woman driving the 4x4 MAY have anticipated faster traffic.

IF the police car had been marked, she may have seen it earlier, or noticed it could be moving faster.

IF her 4x4 had been faster, she may have just got out of the way in time.

IF. IF. IF.

Well it's too late now, just need to learn from our mistakes.

Has no-one noticed that Enforcement doesn't work? Only Education can make our roads safer.

Yep, grade separated junctions would save lives and would have made this collision impossible.

But grade separated junctions don't raise any cash.

Here is a local.live view of the junction. As you can see, anyone heading northbound on the A77 must contend with traffic turning right off the A77 - i.e. slow traffic in the right-hand lane; traffic from Symmington turning right onto the southbound carriageway; southbound traffic turning right into Symmington (e.g. the shoggie); and northbound traffic turning left into Symmington. This is not the place to be travelling considerably above the speed limit without "blues and twos".

I'd say that the driver of the shoggie probably did look. However it was after dark and I suspect the driver didn't correctly judge the speed of the oncoming vehicle - after all, it is very difficult to correctly judge the speed of a pair of headlights approaching head-on without other references. It takes an enormous force to overturn 2.2 tonnes of LWB shoggie and move it sideways the distance shown in the photograph (75 to 100yd), which indicates that the police car was travelling well above the speed limit.

Although SPECS might have been a contributory factor, my finger points at the police driver. He was "on a shout" that required him to travel much faster than the maximum speed a reasonable motorist could expect and seems to have failed to warn other motorists (i.e. didn't use strobes etc.) He failed to anticipate that the 4x4, which had entered the filter lane, might turn. To my mind, this is yet more evidence of poor police driving caused either by incompetence of the officer concerned or inadequate driver training.

_________________
Will

I don't see how you can possibly hold the police driver responsible. He did have right of way. Maybe, maybe, he could have anticipated better and avoided the crash, but you can't know that and can't draw that conclusion from the facts available. For example, you don't know (as far as I can see) whether the Shogun had come to a stop or near stop before it crossed the give way line or whether the driver was travelling at higher speed to 'try and get across' ahead of a bunch of opposing traffic. You don't know that the Shogun was in the filter lane; it may have swerved across from the main carriageway because the driver had nearly missed the turning. You don't know how fast the police was travelling at impact or pre-impact. It may have been doing 120 pre-impact and slowed to 70 because the driver did see and anticipate the crossing vehicle (but not early enough to take successful avoiding action). You may be guessing that the delta-v was in excess of 70mph but you don't know that. Actually, I'd be surprised if it was because, if it was, it would suggest there was little speed loss by the police car pre-impact. And the less speed loss by the police car, the more difficult it is to explain the Shogun crossing without seeing.

There are any number of unknowns and unknowables about the police driver's actions (and possibly the Shogun's). What we do know is that the Shogun crossed the police car's path so was clearly at fault regardless of the police driver's actions. It must be a police response driver's worst nightmare to have a right-turning car pull across when on a high speed run and I have absolute sympathy for him (and his family) and his passenger.

There was a fatal just down the road from me last week. The junction is traffic light controlled, and the lanes are split with filter lanes for right turn. Northbound has filtered lights giving a separate green for right turns, southbound doesn't and a car went to turn right presumably after checking that no vehicles were oncoming. Unfortunately they didn't see the motorbike, and he piled into the side of the car - dead. It might be correct to say that the car was "clearly at fault", but think about it from the car drivers perspective:

You have checked (and double checked) that no vehicles are approaching on the two lanes you have to cross, which is tricky because of the stationary traffic in the opposite right turn filter that blocks your view for all but the last 50 yards - they have to wait for their filter, but your light goes red before that, so you have to go when it appears to be clear - still it is a 30mph limit so there is no reason to expect a high speed vehicle. You also have to check the pedestrian crossing that goes over your intended exit from the junction (for a pedestrian - no lights, just guess when there is a gap in the traffic, and go for it), and you have to align your vehicle correctly into the lane you are going into. So having done your check for oncoming traffic you start moving trying to get across as quickly as you can because your limited view...

Then add in a few facts about the motorcyclist: he was doing about 60mph in the 30 limit (according to witnesses), he was apparently drunk after being in the pub all afternoon, the bike wasn't registered and was in a questionable maintenance state, and it had been raining.

Is it now correct to state that the car driver was "clearly at fault"? Where you have a controlled junction with multiple hazards and a limited window of opportunity, you are forced to take action based on what you can see. The motorcyclist should have been going slower, and in all probability the police driver should also have taken into consideration the possibility that a vehicle might cross in front of them.

unless the motorcyclist ran the red, and despite him being a complete twat, then I'd still say yes.
If your vision is so obscured and there are so many hazards that the turn is dangerous then you should wait until they sort themselves out. Turning on the red when you can see that traffic has stopped is perfectly valid.

Turn the above situations around. If the person turning was on a motorcycle would they have turned without being absolutely 100% certain that there was no oncoming traffic?

I beg to differ. Every time we turn right onto or off a dual carriageway, we cross the path of an oncoming vehicle. That vehicle might not arrive at the junction for some time - but it is still oncoming. The test of whether a driver is in the wrong is whether they acted as a "good driver" would have. For example, if there is no traffic approaching between you and the brow of a hill a third of a mile away, you know that you have roughly 20 seconds to cross the carriageway before any traffic travelling at the speed limit and to which you must give way will arrive. A good driver would recognise this and make adequate progress (i.e. complete the crossing manoeuver). Also if there is a possiblity of conflict with traffic turning right out of of the junction you want to enter, it is reasonable to concentrate on that possible conflict.

Looking on Google Earth I note there is a summit about 700 yd from the scene - which means that if the police car was doing 120 mph, it would have been visible to the Shogun for less than twelve seconds. On the limiter at 155, it would have been visible for just 9 seconds. I assume the police officer concerned knew the road, and so would have known he was approaching a complex junction (look at the aerial view) with possible slow traffic in either lane and/or crossing from either direction.

I've done some rough calcs based on an experimental half "G" deceleration measured as the dynamic friction between a tin tray and grass. This gives the initial velocity of the Shogun after impact in the direction of the road at about 30 metres per second (very approximately), which is nearly 70 miles per hour. So, the police car transferred enough energy to the Shogun to severely buckle its nearside chassis rail and accelerate it from rest in the direction of the road to that velocity. I assume that the Mercedes also deformed enough to dissipate a lot of energy. From the photo (the Mercedes is not in sight), I suspect that the Mercedes went over the Shogun and travelled even further down the road. If so, the kinetic energy was enough to cause the damage to both cars, and accelerate the Shogun to 40, 60, or more mph. I'd be very surprised if the police car was doing less than 120 - and that's approaching a summit, with a dangerous junction just beyond.

_________________
Will

could the passenger have survived such an impact? Or should I say, the passenger in the merc did survive, could the impact speed really have been that high?

johnsher,

perhaps a map will help, so this is the google sat image of the junction

The car was heading south and turning right (into the new Tesco Express). Draw a line between the position of a driver in a car filtering right, past the lorry and you can see that visibility of the oncoming lanes is 50yards at best, and the speeding motorbike was almost certainly in L2 (they always are) giving minimum visibility.

The light sequence doesn't help - when the north traffic gets a filter, the south traffic gets a red, and there are no lights to help with southbound right turns, the north through lights stay green when the south lights go red (and the north right turn lights go green). The driver in the right turn lane doesn't get any time after red when the lanes to be crossed are also red. The north through flow red only occurs when east/west lights go green, but it is possible (as my wife suggested) that when the southbound lights went red that the driver assumed that the north lights had also gone red.

I think that it is a very bad light system design, and that the south right turn should also have a specific right turn light that comes on at the same time as the north right turn.

What I am trying to demonstrate is that as currently installed there is no opportunity for the southbound right turn driver to safely cross the oncoming traffic without waiting for the east/west lights to go green, by which time they are obstructing traffic all traffic that now has a clear green.

From the photo and the satellite image, my best reckoning is that the Shogun was shoved 75 metres or more sideways on grass. A quick experiment suggested that dynamic friction required a force of 0.5 kgf to keep a 1kg bag of flour on a tin tray moving over grass - which equates to a deceleration of about 0.5 G, or about 5 metres per second per second.

Let the velocity of the shoggie in the direction of the road immediately after impact be V1 and the velcocity when the Shogun has come to rest be V2. Now V2 = 0 (i.e. at rest).

The average velocity of the Shogun is its velocity at the start of the slide (V1) plus the velocity at the end of the slide (V2, or zero) divided by 2:

Va = (V1 + 0)/2 = V1/2 .... (1)

But the average velocity is also the distance (75m) divided by the time taken to cover that distance (let this time = t):

Va = 75/t .... (2)

Substituting for (2) in (1):

75/t = V1/2

Thus V1 = 150/t .... (3)

Now assuming constant deceleration, deceleration (let this be "A") is the rate of change of velocity:

A = (V1 - 0)t = V1/t

But A = 5 metres per second per second, so

5 = V1/t

Thus t = V1/5 .... (4)

Substituting for (4) in (3)

V1 = 150/(V1/5)

Thus V1^2 = 750

Thus V1 = 27.4 m/s, which is about 60 mph.

So, based on my simplified analysis, the impact accelerated the Shogun from rest to about 60 mph in the direction of the road. There is considerable scope for error. Nonetheless, it does give an order of things and hence my belief in the speed of the police car.

HTH,

_________________
Will

You're piling speculation upon speculation. You have no idea (or, if you have, you haven't said what the source is) what the impact speed was (apart from some crude speculation) and no idea of the position or speed of either vehicle pre-impact.

Actually

which means the Shogun was emerging from the side turning, crossing the northbound carriageway to head south - NOT crossing the northbound carriageway from the southbound filter lane, as you asserted.

There are all sorts of possible contributory factors to the crash but, as I said before, you can't, without further evidence, lay any responsibility at the door of police driver. You can state with certainty that the Shogun driver must bear a significant share of the responsibility. Crossing a high speed road is potentially hazardous and ought to be done with very great care. It is self-evident that adequate care was not taken because the crash happened. Regardless of the speed of the police car pre-impact, there would certainly have been sufficient time for it to be sighted and once sighted, it's speed assessed before the manoeuvre was started.

It is possible that the police driver should bear some responsibilty if the pre-impact speed was excessive or if there was inadequate observation but we don't know if that was the case - it's pure speculation. It would be equally valid (and equally speculative) to suggest that the Shogun pulled out when the police car was so close that no avoiding action was possible.

Just dealing with the last point, we don't know that he didn't. Perhaps he reduced speed for the junction and then judged (mistakenly) that the Shogun was not going to pull out. We don't know. Perhaps the Shogun pulled out because the driver's foot slipped off the brake when the police car was only a second away, giving the driver no chance to take any avoiding action - we simply don't know.

The case you describe - traffic light junction, 30mph speed limit - is wholly different. Even so, I think that it is ALWAYS possible to say that a driver who crosses the path of a fast moving vehicle, even if it's running a red light, is, at least to some degree, 'clearly at fault' (not necessarily exclusively) for the ensuing collision.

I make the distance less than 50m. The foreground is quite deceptive in the photo but you can see the 4wd is some distance in front of a bus stop. In the aerial view I'm guessing the bus stop is the white blob about 3.5cm from the centre line of the side street. 50 yards is around 4.5cm. 50 yards = 45 metres so 1 cm = 10m. Now that I've done that calculation it means the distance is actually less than 35m or about half of what you're guessing, meaning the impact speed is a whole lot less than 120mph.

If the distance is 50m, the estimated velocity of the 4x4 after impact reduces to about 40 mph, which gives the estimated speed of the police car prior to impact still in excess of 80 mph - which is impact speed, not free travelling speed. If (and it's a big assumption) the energy was split into thirds KE or each vehicle and absorbed in the collision, the calcs still suggest the police vehicle was travelling at well over 100 mph as he approached the brow of the hill. That said, I've checked the picture and it still looks like over 75 metres to me with the 4x4 fetching up on the grass to the front of the first building and well beyond the hedge.

Edited to add: For info, the formula for the velocity of the 4x4 immediately after the impact is:

V = sqrt(A * D)

Where V is the velocity of the 4x4 in metres per second immediately after the impact, A is the deceleration in metres per second per second, and D is the distance in metres that the 4x4 slid after the impact. Since the Mercedes is lighter than the Shogun and much kinetic energy would have been expended in deforming both vehicles, before the impact the Mercedes must have been travelling at more than double (and possibly triple) the speed of the Shogun immediately after the impact.

_________________
Will