Motorway 'Dangerous Driving' Speeding

[7db]

I think there's a good argument for reviewing the 70mph car speed limit on motorways.

The biggest obvious objection is the HGV limit on motorways, which is somewhat harder to change with many of the vehicles having limiters fitter.

A higher car limit might be expected to increase the relative speed of arrival at one of the trickier common situations on a motorway - the HGV passing HGV - and increase the backlog at these pinchpoints. Since these are badly driven enough in the first place, I'm not sure I'd be doubling up there.

A secondary objection is that drivers do seem prone to tailgating even within a 70 limit environment(leaving distances of just a few feet whilst cruising at around 70 in lane three). I suppose it would be the same in a 85 limit environment, just quicker. Seems to be stacking the cards a little higher.

If the trade-off were an 85 limit with SPECS at every on- and off-ramp (a simple system to put in place), would we accept that as a trade-off?

[turbobloke]

7db said:

If the trade-off were an 85 limit with SPECS at every on- and off-ramp (a simple system to put in place), would we accept that as a trade-off?

There is no basis in safety for automated and oppressive enforcement of any speed limit, as exceeding a speed limit is almost always safe. Safe behaviour should not be criminalised.

If the idea of a trade-off is appealing, try deristriction with variable mandatory limits starting at 85 mph and then going down as conditions require, with real people monitoring the situation in real time to make sure the cap fits, and still no automated enforcement.

Any enforcement should be used with judgement and discretion and always related to safety assessments at that time, not relating to what the results might be in an other place in another set of conditions at another time, as we heard on another thread from a pompous magistrate - something like "if you had done that speed in the wet, etc etc".

Return road safety to the care of apolitical specialists and keep uninformed social meddlers out of it.

[smeggy]

7db said:

A secondary objection is that drivers do seem prone to tailgating even within a 70 limit environment(leaving distances of just a few feet whilst cruising at around 70 in lane three). I suppose it would be the same in a 85 limit environment, just quicker.

The same flow rate at higher speeds would result with larger average gap size (distance-wise) between vehicles. If drivers still tailgated it would mean more cars could be squeezed onto motorways, hence increasing the utilisation.

7db said:

If the trade-off were an 85 limit with SPECS at every on- and off-ramp (a simple system to put in place), would we accept that as a trade-off?

More a step in the right direction, but only a step.

[Hollywood Wheels]

turbobloke said:

Resistance is futile

Where the hell did you find that smiley!!!

[7db]

smeggy said:

The same flow rate at higher speeds would result with larger average gap size (distance-wise) between vehicles. If drivers still tailgated it would mean more cars could be squeezed onto motorways, hence increasing the utilisation.

True if they are particles, and a good observation that higher flow speeds means either lower density or higher pipe capacity. My view is that the density is set by the drivers and not by the speed, so it means the same tailgating at higher speeds (and hopefully some big empty bits of motorways for me to drive in).

7db said:

If the trade-off were an 85 limit with SPECS at every on- and off-ramp (a simple system to put in place), would we accept that as a trade-off?

More a step in the right direction, but only a step.[/quote]

I'm not sure I agree, I suspect it's a step in the wrong direction, but it's the kind of compromise that might get brokered between the pro- and anti-speed lobbies. But might be redundant if we have GPS-based road-charging in place instead. How scary is that?

[smeggy]

7db said:

But might be redundant if we have GPS-based road-charging in place instead. How scary is that?

Let's not even go there

[Don]

The point I wanted to make about speed differentials is that if you pass slower traffic at an overly high differential IF they do something silly you have less time to react and take some defensive action.

Lets say we're on a motorway. Two lanes doing seventy to seventy five. Third lane is empty(ish).

If one travels down the third lane at, say, eighty five, you do not hang around in blind-spots overly long and if some idiot just pulls out unless its very, very close you will be able to adjust your speed to avoid them. At ninety five you still can - but there's more drama about it. At 125 there may not be enough time to react.

And yet, whilst totally illegal, 125mph in Lane 1 with absolutely no traffic around might not be unreasonable - after all if there are no other cars around to cause you to change speed or direction the car will be nice and stable...and safe.

All this IMO. But I would not consider passing traffic at overly high speed differentials either above or below the prevailing speed limit.

[7db]

Don said:

And yet, whilst totally illegal, 125mph in Lane 1 with absolutely no traffic around might not be unreasonable - after all if there are no other cars around to cause you to change speed or direction the car will be nice and stable...and safe.

As a slight aside, in the example above, why would you be in Lane 1, except on the approach to right-handers?

[Don]

7db said:

Don said: And yet, whilst totally illegal, 125mph in Lane 1 with absolutely no traffic around might not be unreasonable - after all if there are no other cars around to cause you to change speed or direction the car will be nice and stable...and safe. As a slight aside, in the example above, why would you be in Lane 1, except on the approach to right-handers?

Indeed. I would be in whichever lane was appropriate to increase vision. Lane 1 on right handers, lane 3 on left handers - and probably taking up Lane 2 (for additional safety, less ruts etc) on the straights. Clearly one would also be matching speed to whatever curve ensuring it was always possible to stop in the distance one can see to be clear.

Not that I would have done anything like that at very high speed on a public motorway in the UK, you understand. Oh no. That would have been a private test track or the autobahn.

[apache]

smeggy said:

vonhosen said: they are set for the collective. The motorway collective have proven their ability when above 70, so I would have to disagree.

exactly,

[dcb]

vonhosen said:

We don't have maximum limits set for individuals though, they are set for the collective.

They aren't though, are they ?

It has been measured on UK motorways that most of the traffic
is travelling at more than 70 mph.

Science tells us to set the speed limit at the 85 percentile.

Using either of these rules would tell us to set the limit
at about 80-85 mph.

Setting the speed limit at 70 mph was fine in 1965, but is not now.

Life has moved on, the law hasn't.

We've been through this before a couple of weeks ago, vonhosen.

Want to go through all that again ?

[vonhosen]

dcb said:

vonhosen said: We don't have maximum limits set for individuals though, they are set for the collective. They aren't though, are they ? It has been measured on UK motorways that most of the traffic is travelling at more than 70 mph. Science tells us to set the speed limit at the 85 percentile. Using either of these rules would tell us to set the limit at about 80-85 mph. Setting the speed limit at 70 mph was fine in 1965, but is not now. Life has moved on, the law hasn't. We've been through this before a couple of weeks ago, vonhosen. Want to go through all that again ?

Things haven't changed since we went through it all before either, the limits are still 70 at present. There are other considerations with the setting of limits on motorways than just safe speed. Noise & emissions for instance. Limits as always are a compromise.

[smeggy]

vonhosen said:

Noise

Modern cars are much quieter, so is modern tarmac.

vonhosen said:

emissions

In that case, can we have our old NSL's returned to 60?

[turbobloke]

smeggy said:

vonhosen said: Noise Modern cars are much quieter, so is modern tarmac.

Isn't THAT dangerous to those with poor sight.

smeggy said:

vonhosen said: emissions In that case, can we have our old NSL's returned to 60?

Emissions - equally invalid as a guide to speed limits but the liars in officialdom are desperate. High speed emissions (cf lower speed) have recently been shown to be well below DfT guesstimates. High or low, modern car emissions are no threat to the environment. They provide a living for some ill informed politically motivated pressure group salaried minions, and also provide excuses for politicians to levy taxes and impose restrictions....but...

Transport Research Laboratory investigating a Low Emission Zone for London said:

Restrictions on cars on air quality grounds have been shown not to be warranted

So no excuses.

[dcb]

vonhosen said:

There are other considerations with the setting of limits on motorways than just safe speed. Noise & emissions for instance.

Agree completely.

The ABD has in their analysis of the situation
www.abd.org.uk/motorwayspeedlimit.htm
that the effect on the environment would be neglible.

They illustrate this by computing that the increase in
CO2 emmisions by moving the UK mway speed limit from
70 mph to 80 mph would be 0.074%.

I don't know about you, but I'd regard 0.074% as not
worth bothering about.

They also estimate the increase in noise at less than 3dB,
which is the limit that the human ear can detect.

I don't know about you, but a difference that I can't
hear I tend not to worry about.

Let's also not forget that most motorways are through rural
areas for obvious reasons - no one likes a motorway
at the end of their garden.

Vonhosen - I'd recommend reading the document I have
provided a link for. It appears to contain quite a bit
of science, not hearsay and emotion.

[turbobloke]

dcb said:

The ABD illustrate this by computing that the increase in CO2 emmisions by moving the UK mway speed limit from 70 mph to 80 mph would be 0.074%.

Yes, and that was using their 'old' figures! The SMMT / DfT's own stats have been revised and we really must update this figure, it will be even smaller now.

[baz1985]

If you can spot unmarked cars, are aware of marked car observation points, slow down at junctions to check for sliproad vascar, know the scamera van locations, check your rear view mirror, speed when your view isn't restricted by a line of HGVs etc..you can speed as much as you like.

[dcb]

turbobloke said:

Yes, and that was using their 'old' figures! The SMMT / DfT's own stats have been revised and we really must update this figure, it will be even smaller now.

In an ideal world, it would be a good idea if someone at the
ABD updated the prices in that document.

1998 prices are now eight years old.

Over 400 million quid to be saved I read.

That will pay for quite a few hospitals in the UK
or bullets and bombs for Iraq/Afghanistan.

[vonhosen]

dcb said:

They illustrate this by computing that the increase in CO2 emmisions by moving the UK mway speed limit from 70 mph to 80 mph would be 0.074%. I don't know about you, but I'd regard 0.074% as not worth bothering about.

But doesn't reducing the limit to 65mph create a greater gain for emissions ?
We have signed up to international agreements with regards to reductions in emissions and they won't come from one area alone. Lots of little areas will have to add their combined percentages to help in that.

dcb said:

They also estimate the increase in noise at less than 3dB, which is the limit that the human ear can detect. I don't know about you, but a difference that I can't hear I tend not to worry about. Let's also not forget that most motorways are through rural areas for obvious reasons - no one likes a motorway at the end of their garden.

A lot of our motorways run close to residential areas in some sections & I believe the last time that motorway limits were considered for a possible rise, it was increased noise levels that were a factor in leaving the limit as is.

dcb said:

Over 400 million quid to be saved I read.

Which would probably get you one large hospital in todays money.



>> Edited by vonhosen on Saturday 6th May 10:04

[turbobloke]

vonhosen said:

dcb said: They illustrate this by computing that the increase in CO2 emmisions by moving the UK mway speed limit from 70 mph to 80 mph would be 0.074%. I don't know about you, but I'd regard 0.074% as not worth bothering about. But doesn't reducing the limit to 65mph create a greater gain for emissions ? We have signed up to international agreements with regards to reductions in emissions and they won't come from one area alone. Lots of little areas will have to add their combined percentages to help in that.

Carbon Dioxide emissions in the UK have been falling continuously for decades. Between 1970 and 1990 the reduction was 10% (source: Royal Commission Report on Environmental Pollution, Transport and the Environment, 1994) despite a massive increase in traffic over that period. Since then the reductions in emissions have continued, the reduction from 1997 to 2004 alone was a further 10% (source: SMMT).

Then we have the transport system as a whole. You may have noticed the increasing use of brighter l.e.d. traffic lights at junctions and roadworks. These new 'lamps' are - like it says - l.e.d. devices, it's a good bit of UK technology exploiting gallium nitride with indium doping to give the required colours. They are brighter and so less susceptible to daylight glare (safer), they're more reliable with a longer working life, and they cost substantially less to install and maintain. A large part of this financial saving is in energy costs due to the much lower consumption by l.e.d. devices. When the network of traffic lights has been fully updated the saving in carbon dioxide reductions will amount to two power stations' output of carbon dioxide each year. This is already well on the way, more than enough little bits don't you think?

It's still wrong-minded. Driving a car typically produces 3.6 tonnes of carbon dioxide per year (source: Rover cars) while heating/lighting an average home generates 9.6 tonnes (source: National Energy Foundation). This is where the scope for real improvements lies, but note the hypocrisy of the government which taxes heating fuel at 5% while mobility fuel a.k.a. petrol has an overall tax and duty rate of 300% in spite of the fact that buildings - not just homes - emit twice as much carbon dioxide as cars.

The Kyoto Protocol on which this nonsense is based is pointless anyway. Even within the IPCC's flawed climate models, the best 'gain' if the crippling reductions are met and we regain third world status on time, will be 0.04 deg C, which is buried deep within the noise of any measurement hoping to detect it. Utterly pointless.