How do I get the mobile speed camera on our road?

[spindrift]

At least Swindon are going a step in the right direction, they covered up with a big 'not in use' bag the last of their camera's.

 

Not quite, mobiles remain and will be used by the cops.

 

It's a dangerous experiment, when a death occurs where speed is implicated the family may have grounds to sue Wiltshire council.

 

Motorways, who cares, raise the limit. All urban residential roads should have a camera-enforced 20mph limit like the ones in Hull that are such an astounding success.

[convert]

At the scene of a fatal crash the investigating officers close the road and start off with the premise that this could be the site of an unlawful killing.

 

Their mandatory forensic analysis of the road, surface, gradient, witness statements, length of skid marks, car and tyre condition .... all help to build up a picture of what happened as objectively as they can.

 

I would not know whether it could be called absolutely scientific but years of experience and an actuarial, probability and statistical analysis of what has already happened elsewhere allows them to state in broad brush terms "hit at x mph and you survive, hit at x+10 mph it's more likely to be fatal. So that's where these figures come from - they are in no way made up. I stress "broad brush" since there's always someone who survives miraculously or someone who would normally have survived an impact but doesn't.

 

 

To back up this, there's numerous videoed tests of cars doing x, x+2,5 and x+10 mph, braking at a known point to stop the cars on their nose and a GPS clocking of the varied impact speeds. The difference made by just 2, 5 and 10 mph extra speed shocks most drivers when they watch the videos and this is in perfect road and weather conditions and the tests did not require the driver to think about braking. So the message from these is that actual impacts in the real world will always be worse than the vieoed test results, shocking as they are, and that speed doesn't kill IMPACT speed kills.

Also, because of the laws of physics, just a few mph extra makes a massive difference to the impact speed if an impact happens.

 

Such an understanding of speed and of the laws of physics should shape our choice of speed (what we think of as "appropriate") and it renders the well-worn, cliched arguments of "increase speed limits ... better brakes on modern cars ... HC figures out of date ..." largely irrelevant, missing the point and redundant since the videos show modern car performing against modern car.

 

I take issue with the authorities for missing a trick in getting the driving public on board - very few drivers have anything but a skin-deep appreciation of the subject. We nod sagely at a video showing a young girl peeling herself off the pavement. Some of the wording of the public info ads is extremely suspect. Take the snappy "hit me at 30 and I have an 80% chance of surviving."

Hell no, you cannot afford to hit a pedestrian at 30 mph without braking. Hopefully you will brake and get the impact speed down to something a lot lower. For every mph above the 30 (as an arbitrary figure) you guarantee an impact that is exponentially higher.

 

Mine's not so snappy, is it?

 

Some excellent points.

 

I Agree that impact speed is a factor in the extent to which a pedestrian is injured.

 

What sort of impact (pardon the pun) does the vehicles mass have?

 

Surely being hit by a HGV at 25mph is going to be a lot worse than being hit by a smart car at the same speed.

[convert]

Not quite, mobiles remain and will be used by the cops.

 

It's a dangerous experiment, when a death occurs where speed is implicated the family may have grounds to sue Wiltshire council.

 

Motorways, who cares, raise the limit. All urban residential roads should have a camera-enforced 20mph limit like the ones in Hull that are such an astounding success.

 

Isn't the problem with mobiles their lack of visibilty.

 

Surely, if speeding cameras are being used as a deterrent to speeding and not as a revenue stream, then we should be made more aware of the location of mobile cameras (I'm not talking about pre-published locations on t'internet, but great big signs on the roadside).

 

I'm not entirely sure that we should just raise the limit on motorways; we should introduce variable limits. Just like I'm not sure that we should lower the limit on all urban roads to 20mph. Again variable limits would be much better.

 

We could then adjust the speed up or down according to several factors:-

 

• Time of day

• 
  Weather conditions

• 
  traffic conditions
  

 

We could also go one step further and introduce a lower speed limit for HGV's, as surely the dangers they pose at speeds lower than the current limit far exceed the dangers posed by a small car.

[DT Ralge]

Isn't the problem with mobiles their lack of visibilty.

 

Surely, if speeding cameras are being used as a deterrent to speeding and not as a revenue stream, then we should be made more aware of the location of mobile cameras (I'm not talking about pre-published locations on t'internet, but great big signs on the roadside).

 

I'm not entirely sure that we should just raise the limit on motorways; we should introduce variable limits. Just like I'm not sure that we should lower the limit on all urban roads to 20mph. Again variable limits would be much better.

 

We could then adjust the speed up or down according to several factors:-

 

• Time of day

• 
  Weather conditions

• 
  traffic conditions
  

 

We could also go one step further and introduce a lower speed limit for HGV's, as surely the dangers they pose at speeds lower than the current limit far exceed the dangers posed by a small car.

 

Changing the limits according to the weather on the faster roads already happens in europe and would be a good idea for here but the DfT is VERY slow at adopting good ideas.

Changing for the time of the day has an attraction but imagine those on here bleating about not knowing what time it was etc etc. Not a goer for me.

There are already lower limits for vans and hgv's out of town. 90% of the van drivers I sit with don't know that, though.

[spindrift]

I guess my argument to raise the speed limit on motorways is because on those roads the danger is externalised to vulnerable road users to a much smaller degree. So the risk is self-imposed.

 

It's similar to the argument that road safety would be improved by having an iron spike fixed on the steering wheel of all cars, aimed at the driver's heart...

[Bonjon]

It's similar to the argument that road safety would be improved by having an iron spike fixed on the steering wheel of all cars, aimed at the driver's heart...

 

Or maybe if more people payed attention to the green cross code when crossing the road and not Greenday thats playing through their ipods!!

[DT Ralge]

What sort of impact (pardon the pun) does the vehicles mass have?

 

Surely being hit by a HGV at 25mph is going to be a lot worse than being hit by a smart car at the same speed.

 

Dunno, quite simply.

'Cos you are then into not only considering the mass at a given velocity but also what parts of the body get hit.

How serious or fatal the injuries turn out to be is a bit of a lottery around innumerable factors: e.g. height and composition of bumper, bonnet, height, weight etc of pedestrian, angle of pedestrian's body on impact etc.

[spindrift]

Or maybe if more people payed attention to the green cross code when crossing the road and not Greenday thats playing through their ipods!!

 

 

I would like to live where children CAN play in the street, people can cross slowly, cyclists mingle with no conflict. Humans competing for limited resources invariably come into conflict. I'm interested in reducing that conflict and lessening the attendant misery, not allocating blame. The penalty for listening to Greenday ought not be death. People get distracted, you manage that fact without blaming them if they die because they're distracted, or far more commonly, killed when the driver is distracted.

[Cyclone]

Using data from actual road crashes, scientists at the University of Adelaide estimated the relative risk of a car becoming involved in a casualty crash – a car crash in which people are killed or hospitalised – for cars travelling at or above 60 kilometres/hour. They found that the risk doubled for every 5 kilometres/hour above 60 kilometres/hour. Thus, a car travelling at 65 kilometres/hour was twice as likely to be involved in a casualty crash as one travelling at 60. For a car travelling at 70 kilometres/hour, the risk increased fourfold. For speeds below 60 kilometres/hour the likelihood of a fatal crash can be expected to be correspondingly reduced.

There you go again with the unqualified and blatantly untrue statements.

If the statement above were true, then motorways would be death traps, they are not, they are the roads with the lowest number of crashes.

70 mph limit dual carriageways are also not death traps.

The relative risk of a crash does NOT increase with speed.

 

Reaction time

 

One reason for this increased risk is reaction time – the time it takes between a person perceiving a danger and reacting to it. Consider this example. Two cars of equal weight and braking ability are travelling along the same road. Car 1, travelling at 65 kilometres/hour, is overtaking Car 2, which is travelling at 60 kilometres/hour. A child on a bicycle – let's call him Sam – emerges from a driveway just as the two cars are side-by-side. The drivers both see the child at the same time and both take 1.5 seconds before they fully apply the brakes. In those few moments, Car 1 travels 27.1 metres and Car 2 travels 25.0 metres. The difference of 2.1 metres might seem relatively small, but combined with other factors it could mean the difference between life and death for Sam.

 

The figure of 1.5 seconds is the reaction time of average drivers. A driver who is distracted (eg, listening to loud music, using a mobile phone or has drunk alcohol) may take as long as 3 seconds to react.

Loud music, maybe you're just showing your age there.

 

Braking distance

 

The braking distance (the distance a car travels before stopping when the brakes are applied) depends on a number of variables. For example, the slope or grade of the roadway is important – a car will stop more quickly if it is going uphill because gravity will help. The frictional resistance between the road and the car's tyres is also important – a car with new tyres on a dry road will be less likely to skid and will stop more quickly than one with worn tyres on a wet road. If slope and frictional resistance are equal, the factor that has most influence on braking distance is initial speed.

 

The formula used to calculate braking distance can be derived from a general equation of physics:

 

 

 

where Vf is the final velocity, V0 is the initial velocity, a is the rate of deceleration and d is the distance travelled during deceleration. Since we know that Vf will be zero when the car has stopped, this equation can be re-written as:

 

From this we can see that braking distance is proportional to the square of the speed – which means that it increases considerably as speed increases. If we assume that a is 10 metres per second per second and assume that the road is flat and the braking systems of the two cars are equally effective, we can now calculate braking distance for cars 1 and 2 in our example. For car 1, d = 16.3 metres, while for Car 2, d = 13.9 metres.

 

http://www.science.org.au/nova/058/058key.htm

 

We need more cameras, more trafpol, more red light cameraS.

 

There are more uninsured cars in the UK (1.6m) than commuting cyclists (1m).

 

I think you might be looking for

 

S = ut + (at^2)/2

in combination with

 

t = u/a

 

giving

 

S = (u^2)/a + (u^2/a)/2

 

S = 1.5 * (u^2)/a

 

high school physics.

 

I guess your copy and paste there didn't include the start of the example as we don't know what speed car 1 and 2 were doing.

 

If it was 30 mph (that's 13.4 m/s), 35 is (15.6 m/s)

I'll accept a as 10 m/s/s.

 

1

S = 27 m

2

S = 36 m

 

This tells us nothing about relative impacts though, it's just telling us the breaking distance.

 

The impact to the pedestrian is proportional to the acceleration induced by the car, f=ma (force = mass * acceleration), where mass in this case is the pedestrians mass. Since the relative masses are so large we can pretty much ignore the amount that the pedestrian slows the car.

 

It's still no help though, knowing we can't calculate the acceleration because it depends on so many factors, the vehicle involved, the angle of the impact and so on. Modern vehicles are kinder towards pedestrians than older ones, and cars are less harmful than larger flat fronted vehicles.

I think I read somewhere that in relatively low speed impacts, it's not being hit by the car that kills you, it's your head hitting the road afterwards.

 

It's your grasp of statistics that I find amusing.

I've lost a friend to a driver running a red light at a pedestrian crossing, I don't find much amusement in visiting her grave once a year. It doesn't make me hysterical about car speed though, the car that killed her wasn't speeding, was taxed and insured and she's still dead.

 

If cameras were primarily placed in 30 zones, near to places where pedestrians are likely to be at risk then they never would have attracted a bad reputation.

 

Putting them on motorways (the M3 is it), A roads that haven't even opened (Hampshire was it?) and on long straight stretches of dual carriageway (all over the place) gave them a reputation for being cash generating devices.

 

We were better off with more traffic police and less cameras than we are now.

[Cyclone]

I would like to live where children CAN play in the street, people can cross slowly, cyclists mingle with no conflict. Humans competing for limited resources invariably come into conflict. I'm interested in reducing that conflict and lessening the attendant misery, not allocating blame. The penalty for listening to Greenday ought not be death. People get distracted, you manage that fact without blaming them if they die because they're distracted, or far more commonly, killed when the driver is distracted.

 

55% of pedestrian deaths are the sole mistake of the pedestrian.

I know you don't like it, but that's the number.

 

We all have to take responsibility, drivers and pedestrians. If I walk in front of a car at any speed it's going to be extremely dangerous. It shouldn't be down to the law or the driver to protect me, it's down to me to look.

And then given that accidents and mistakes will still happen, not speeding is the responsibility of the car driver in order to keep the consequences of mistakes by pedestrians at an acceptable level.