Rugby is a form of child abuse, study says

[baldpaul101]

The cost to society of reducing the speeds to 20 mph - more pollution in urban areas directly from emissions and indirectly from tyres and brakes, cost in fuel, engine strain etc - has to be weighed against this.

There's plenty of readily available studies that show reduced pollution, & less wear & tear on engines, brakes & tyres because people aren't speeding up or slowing down. However some cities had an average speed of 17 mph before the implementation of a 20 mph limit so not entirely sure what the point was.
Like most things you can find "facts" to prove just about anything you want.

[backdoc]

Cars and most other vehicles are not engineered to run at or below 20 mph.

[Bloke in North Dorset]

Jut to dip my oar in:

NWW is right about the cause of accidents, perhaps adding the odd act of God eg trees falling, mechanical failure at the wrong time, and its accidents that cause deaths, but that doesn't change the calculations because we're dealing humans.

As backdoc says there is a trade off between the opportunity cost of time lost and other externalities of driving slower (in areas where you could be driving faster) and lives saved. Yes I know its a horrible calculation but we do it all the time: NICE uses Quality Life Years when calculating whether or not a drug or treatment should be available on the NHS. The last time I heard a figure it was that Network Rail values a life saved at ?1m. So the question is how many fatalities are we prepared to put up with and at what cost.

But there's another area to consider: Risk mitigation. We've made driving and being a passenger incredibly safe and the survival numbers must be trending towards zero by now, or would be if drivers didn't feel so safe*. That added safety: seat belts, air cushions, roll cages, crumple zones etc means that drivers can be more inattentive or drive faster for the same level of risk if they didn't have all those safety features.

I'd add that drivers going slower are also less attentive either through frustration, boredom or the belief that they aren't in danger, but the numbers do show the accidents are more survivable for pedestrians.

If you really want drivers to slow down and pay attention, strip out all the safety features and put a 6" metal point in the middle of the steering wheel.

I'm not against 20mph zones in principle, just blanket legislation. We visit Germany a lot and they have them outside schools and kindergartens, old people homes and the like and also for noise reduction between 10am and 6am in some villages. (Its a Federal country so States differ).

*One of the biggest drivers of survivability is response times, but that's the same for pedestrians.
We also value people's time quite highly cf the huge amounts to be spent on HS2 to save 10 to 20 minutes between Birmingham and London (And yes I'm aware the Dept for Transport screwed up the numbers and then had their fingers on the scales, but the premise still stands).

[baldpaul101]

Cars and most other vehicles are not engineered to run at or below 20 mph.

I don't think is correct any more. If you place your car in 3rd and drive at 20mph the engine will be virtually idling & you will be burning almost no fuel. There's less accelerating up to speed & braking again so less omissions & less wear & tear on your vehicle.

[backdoc]

Baldpaul, I am not talking about drivability. I am talking about stress on the drivetrain, and about fuel efficiency and pollution. The vehicles are optimised for A road and Dual carriageway usage, not urban crawls. My electric car is fine at 20 mph, but my petrol and diesel vehicles less so. If you make a vehicle efficient at one thing, you will have compromised on another. Safety is the obvious example. You are much safer in a modern car, but it weighs a lot more as a consequence, and therefore it burns a lot more fuel and creates more pollutants.

[NellyWellyWaspy]

Cars and most other vehicles are not engineered to run at or below 20 mph.

I don't think is correct any more. If you place your car in 3rd and drive at 20mph the engine will be virtually idling & you will be burning almost no fuel. There's less accelerating up to speed & braking again so less omissions & less wear & tear on your vehicle.

No engine is designed to idle and live long. If your engine spends most of its time at idle, it will die a very premature death. The one owner, little old lady who goes half a mile to church once a week is the worst one to buy a car off. The bearings will take a hammering, and the oil will soon have forbidden glitter (aluminium and copper flakes), leading to excessive wear on the cams, lifters, oil pump and many other parts, and oil passage and filter blockages.

[coddy]

How are motor bikers managing, WWW?  We're waiting for them to arrive over the border from Abergavenny in massed hordes.  All doing  80 mph and going vvvvrrrrmmmmm.  Surely a motor bike going at 20 mph is going to fall over??

Wonky has reminded of an old joke


Is the motorbike still for sale?

Yes

What's the lowest you can go on it?

About 4mph, any less and I'll tip over!

[InBetweenWasp]

"Eric Anderson is Professor of Sport, Masculinities & Sexualities. He holds four degrees, has published numerous books and over 60 peer-reviewed journal articles. His research is regularly featured on international television, in print and digital media.

He is the leading academic expert on gay men in sport, and the architect of Inclusive Masculinity Theory, which was generated from his research showing that decreased homophobia leads to a softening of heterosexual masculinities. This permits young men to kiss, cuddle and maintain bromances with other males, while also leading to semi-sexual behaviours between men and the increased recognition of bisexuality. "

No bias here, then   

Of late, it feels like when an expert needs to be quoted, it's because what's being suggested is usually a load of boll*cks.