Smart motorways are (not) more dangerous

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Boustrophedon
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Re: Smart motorways are (not) more dangerous

Post by Boustrophedon » Sat Jan 30, 2021 11:36 am

dyqik wrote:
Tue Jan 28, 2020 10:03 pm


The US highways that do this do it by having a string of concrete barriers that a special equipped vehicle can move from one side of the shared lanes to the other in the middle of the day/night.

The other method is to have HOV/express lanes that are separated from the main lanes in both sides, and which are only open to toll-paying/vehicles with 2 or more passengers, and which can be closed for each direction as appropriate.
These existed on the M25 for a while but they sold off the barrier moving vehicle. Some were installed installed on the M20. https://www.highwaysindustry.com/moveab ... n-the-m20/
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Re: Smart motorways are (not) more dangerous

Post by bob sterman » Sun Jan 31, 2021 8:04 am

sTeamTraen wrote:
Fri Jan 29, 2021 6:27 pm
In the UK you also have a lot of major trunk A-roads with the same 70mph speed limit as motorways, no hard shoulder, bicycles and milk floats allowed (IIRC - maybe only sometimes?), and vehicles joining from stop signs coming out of little side at 90 degrees. :o
True. But on many A-road sections there is a grassy "soft shoulder" that you stand a good chance of being able to get most of your car onto. Whereas on new smart motorways with all lane running there is a crash barrier to prevent vehicles leaving the carriageway.

No idea whether lack of crash barriers and an accessible "soft shoulder" (perhaps with trees to crash into) is on balance a safer alternative - but it does give you the option of leaving the carriageway.

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Re: Smart motorways are (not) more dangerous

Post by Grumble » Thu Feb 18, 2021 1:23 pm

Driving down a smart motorway this morning there was someone parked up on the grass verge at the side. Luckily there was a verge at that point.
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Re: Smart motorways are (not) more dangerous

Post by IvanV » Tue May 18, 2021 6:56 pm

This country has a big problem that building infrastructure here is unduly expensive in comparison to our continental neighbours. As we are not richer than them, indeed mostly they are richer than us, this means we can't afford to build as much infrastructure as them. And since infrastructure is what lubricates our economy, it results in our economy being rickety.

The worst example is the railways. Railway construction seems to be about 3 times what it costs on the continent.

The countries that are more expensive than us for building roads in Europe are Norway, Switzerland and Austria. There is a reason building roads is very expensive precisely in throse three countries. They are very mountainous. And have a high cost labour too. So, adjusting for terrain and labour costs, I think we come out about 50% more expensive than the continental benchmark for road-building cost.

The present discussion is actually an illustration of one of the contributory reasons to this problem. Somehow the British public succeed in demanding higher standards of safety in the construction of our infrastructure than is normal on the continent. To the extent that the extra money spent on making each piece of infrastructure a bit safer would be better spent elsewhere in terms of saving lives. As you have noticed further up the thread, motorways are very safe roads in comparison to the average. 80% of traffic is on other roads. ALR smart motorways are similarly safe to unimproved older bits of motorway. And they will be a bit better when they get round to putting in the automated stopped vehicle detectors that they originally promised, and which the government has now told them they really have to install.

So ALR smart motorways are a relatively cheap way of increasing the capacity of a motorway, and produces a road safer than most other roads in the country. If that's not acceptable to you, you are in effect insisting on the goverment spending money saving a few lives, when money that would have saved many more lives if it had been spent somewhere else. (A trick that the railway operators have pulled off like almost no other.)

There are people who say they don't want more roads, because more roads just increases traffic. Yes, of course new roads increase traffic. It's kind of the point. If you have no roads, you have no traffic. Build a road and you get traffic. Build another road and you get more. Remains true as you make further improvements. he simple reason is that if you make it less annoying for people to make a journey, they are more likely to make it, or make it more often. And it is also obviously true of improvements to any other transport mode. It's not controversial, or shouldn't be. But it's not a relevant reason that means you shouldn't have more roads. 0 roads is clearly not the correct amount of roads.

So, the question I ask to people who don't want more roads, or road capacity expansions, is, "What is the right amount of roads?" An Ethiopian quantity of roads? When should we have stopped building/expanding them? In 1930? In 1950? In 1970? Were those the right amount of roads? Today's roads are just right but no more?

Perhaps we should have more railway lines. But that would be easier to support if we managed to build railways to continental cost levels. HS2 is costing something like twice the cost of the entire high speed railway program of Spain to date.

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Re: Smart motorways are (not) more dangerous

Post by shpalman » Sun May 23, 2021 8:15 pm

molto tricky

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Re: Smart motorways are (not) more dangerous

Post by nekomatic » Mon May 24, 2021 10:17 am

IvanV wrote:
Tue May 18, 2021 6:56 pm
So, the question I ask to people who don't want more roads, or road capacity expansions, is, "What is the right amount of roads?" An Ethiopian quantity of roads? When should we have stopped building/expanding them? In 1930? In 1950? In 1970? Were those the right amount of roads? Today's roads are just right but no more?
Clearly 'every square metre of the country is road' is also undesirable, so there must exist an optimum greater than zero but less than that. What that is will obviously depend on how we weight the various costs and benefits of roads, which may change over time but is likely to stay controversial. People who oppose any given road project probably feel that the many externalities outweigh the benefits, and their position should be tested not with a silly strawman but by examining whether both sides understand all the costs and all the benefits and what the basis is for their disagreement on their weighting.

Applying the same good logic that you advocated for smart motorways, the question is not 'should we build roads yes or no', it is 'with the resources available, is any given road project the best use of them?' It certainly seems defensible to me that the answer will sometimes be 'no'.

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Re: Smart motorways are (not) more dangerous

Post by Fishnut » Mon May 24, 2021 11:13 am

I went to a talk not long before the first lockdown where one of the speakers was from the Welsh Future Generations Commission. They talked about how all their legislation has to be considered in terms of the impact on future generations. The planned M4 relief road was scrapped in part because of this - it was decided that spending £1.6 billion on 13 miles of motorway was not the best use of that money,
Not only did the project not align with Wales’ carbon reduction targets, [the Future Generations Commissioner] said, it also went against the Act’s well-being goals of supporting the resilience of ecosystems and a healthier Wales. It also did not take into account future trends such as increased homeworking – something which has been fast forwarded as a result of COVID-19 and research suggests is likely to become a new normal with the potential to reduce congestion on our roads.
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Re: Smart motorways are (not) more dangerous

Post by science_fox » Mon May 24, 2021 11:15 am

sTeamTraen wrote:
Fri Jan 29, 2021 6:27 pm
shpalman wrote:
Mon Jan 25, 2021 12:14 pm
plodder wrote:
Mon Jan 25, 2021 12:07 pm
One problem here is that non-smart motorways are also stupidly dangerous.
Less dangerous than normal roads.
In the UK you also have a lot of major trunk A-roads with the same 70mph speed limit as motorways, no hard shoulder, bicycles and milk floats allowed (IIRC - maybe only sometimes?), and vehicles joining from stop signs coming out of little side at 90 degrees. :o
60mph!
Signage specified dual carriageways are 70 - and yes open to bicycles milk floats et al. Junctions are usually with feeder lanes. But all other roads including those that have a central reservation but no dual carriageway sign are 60.

I'm not sure it makes a big difference to your argument, but thought we should at least get the speed limit right.
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Re: Smart motorways are (not) more dangerous

Post by Gfamily » Mon May 24, 2021 11:43 am

science_fox wrote:
Mon May 24, 2021 11:15 am
sTeamTraen wrote:
Fri Jan 29, 2021 6:27 pm
shpalman wrote:
Mon Jan 25, 2021 12:14 pm

Less dangerous than normal roads.
In the UK you also have a lot of major trunk A-roads with the same 70mph speed limit as motorways, no hard shoulder, bicycles and milk floats allowed (IIRC - maybe only sometimes?), and vehicles joining from stop signs coming out of little side at 90 degrees. :o
60mph!
Signage specified dual carriageways are 70 - and yes open to bicycles milk floats et al. Junctions are usually with feeder lanes. But all other roads including those that have a central reservation but no dual carriageway sign are 60.

I'm not sure it makes a big difference to your argument, but thought we should at least get the speed limit right.
A pedant writes:
the Highway Code wrote:A dual carriageway is a road which has a central reservation to separate the carriageways
So specific "dual carriageway" signage is not required for the 70mph limit to apply.

https://www.highwaycodeuk.co.uk/multi-l ... eways.html
https://www.gov.uk/speed-limits
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Re: Smart motorways are (not) more dangerous

Post by bob sterman » Mon May 24, 2021 12:13 pm

Gfamily wrote:
Mon May 24, 2021 11:43 am
A pedant writes:
the Highway Code wrote:A dual carriageway is a road which has a central reservation to separate the carriageways
So specific "dual carriageway" signage is not required for the 70mph limit to apply.
I hope traffic islands are excluded from the definition of "central reservation" - otherwise they could create a loophole for (very short) drag races that involve ridiculous g-forces. :shock:

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Re: Smart motorways are (not) more dangerous

Post by science_fox » Mon May 24, 2021 12:45 pm

A pedant writes:
the Highway Code wrote:
A dual carriageway is a road which has a central reservation to separate the carriageways
So specific "dual carriageway" signage is not required for the 70mph limit to apply.
Good pedanting!
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Re: Smart motorways are (not) more dangerous

Post by Sciolus » Mon May 24, 2021 2:03 pm

I've always wondered what the national speed limit is on roundabouts.

But IME most dual carriageways either have lower limits (60 or 50 in rural areas) or have been semi-motorwayised with slip road access, straightening and the like. Rarely, they have a cyclists prohibited sign. But I've never seen a 70 dual carriageway with a hard shoulder. But (again) real-world speeds tend to be lower than motorways (less expectation that 70 is the minimum and 80+ is the norm). So overall I dunno.

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Re: Smart motorways are (not) more dangerous

Post by IvanV » Tue May 25, 2021 12:11 pm

nekomatic wrote:
Mon May 24, 2021 10:17 am
IvanV wrote:
Tue May 18, 2021 6:56 pm
So, the question I ask to people who don't want more roads, or road capacity expansions, is, "What is the right amount of roads?" An Ethiopian quantity of roads? When should we have stopped building/expanding them? In 1930? In 1950? In 1970? Were those the right amount of roads? Today's roads are just right but no more?
Clearly 'every square metre of the country is road' is also undesirable, so there must exist an optimum greater than zero but less than that. What that is will obviously depend on how we weight the various costs and benefits of roads, which may change over time but is likely to stay controversial. People who oppose any given road project probably feel that the many externalities outweigh the benefits, and their position should be tested not with a silly strawman but by examining whether both sides understand all the costs and all the benefits and what the basis is for their disagreement on their weighting.

Applying the same good logic that you advocated for smart motorways, the question is not 'should we build roads yes or no', it is 'with the resources available, is any given road project the best use of them?' It certainly seems defensible to me that the answer will sometimes be 'no'.
Absolutely. And all public investment does have to be justified with quite elaborate analysis and cases. And Britain does this more carefully and consistently than most other countries.

Generally speaking, road projects that the government chooses to proceed with show quantified socio-economic returns that are high in comparison with most other public spending, and is high on the list for socio-economic return in comparison to alternative road investments. Sometimes they prioritise a scheme for another reason, and these will tend to be among the most controversial.

Stonehenge tunnel is one such particularly difficult case. It doesn't have a straightforward economic case - the road capacity benefit, and benefits of by-passing the small village of Winterbourne Stoke the road currently goes through, does not justify the cost of the tunnel by the usual criteria. The major additional benefit, that doesn't have a standard method for valuing it, is not having a busy traffic-jam-ridden road running visible/audible close by Stonehenge. The government chose to proceed with the scheme because it impliedly gave a large value to that benefit. Then there have been arguments about the damage caused by the actual selected scheme, which are again hard to value. Other schemes that reduce those damages would be much more expensive, and have other different local costs. It's all very difficult. Do nothing and you stil have a very busy traffic-jam-ridden road running close visible/audible from Stonehenge, which is not nice. You could just close the road, but the large volume of traffic would have to go somewhere.

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Re: Smart motorways are (not) more dangerous

Post by IvanV » Tue May 25, 2021 3:36 pm

science_fox wrote:
Mon May 24, 2021 12:45 pm
A pedant writes:
the Highway Code wrote:
A dual carriageway is a road which has a central reservation to separate the carriageways
So specific "dual carriageway" signage is not required for the 70mph limit to apply.
Good pedanting!
Not perfect pedanting. Speed limits are a matter of law and the Highway Code is not law. Although it may sometimes accurately state the law, it does not carefully distinguish between "advice" and "legal obligation". I'm pretty sure HC is right on this specific occasion, but for an authoritative pedanting on such matters, you should in general quote the law.

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Re: Smart motorways are (not) more dangerous

Post by Gfamily » Tue May 25, 2021 4:07 pm

IvanV wrote:
Tue May 25, 2021 3:36 pm
science_fox wrote:
Mon May 24, 2021 12:45 pm
A pedant writes:
the Highway Code wrote:
A dual carriageway is a road which has a central reservation to separate the carriageways
So specific "dual carriageway" signage is not required for the 70mph limit to apply.
Good pedanting!
Not perfect pedanting. Speed limits are a matter of law and the Highway Code is not law. Although it may sometimes accurately state the law, it does not carefully distinguish between "advice" and "legal obligation". I'm pretty sure HC is right on this specific occasion, but for an authoritative pedanting on such matters, you should in general quote the law.
I understand its use of "You should" vs "You must" is indicative of whether a law is being mandated.
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Re: Smart motorways are (not) more dangerous

Post by IvanV » Tue May 25, 2021 4:31 pm

Gfamily wrote:
Tue May 25, 2021 4:07 pm
(...Highway Code...)
I understand its use of "You should" vs "You must" is indicative of whether a law is being mandated.
Yes, you are right, it does indicate that, though a couple of the "musts" are questionable. What I should have said is that it tends to simplify, and if you need to know the details, or an authoritative statement, you have to go to legislation.


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Re: Smart motorways are (not) more dangerous

Post by headshot » Wed Jun 09, 2021 2:45 pm

More or Less have a piece on this in their latest episode: https://www.bbc.co.uk/programmes/m000wsf0

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Re: Smart motorways are (not) more dangerous

Post by lpm » Fri Jul 30, 2021 3:57 pm

IvanV wrote:
Tue May 25, 2021 12:11 pm
Stonehenge tunnel is one such particularly difficult case. It doesn't have a straightforward economic case - the road capacity benefit, and benefits of by-passing the small village of Winterbourne Stoke the road currently goes through, does not justify the cost of the tunnel by the usual criteria. The major additional benefit, that doesn't have a standard method for valuing it, is not having a busy traffic-jam-ridden road running visible/audible close by Stonehenge. The government chose to proceed with the scheme because it impliedly gave a large value to that benefit. Then there have been arguments about the damage caused by the actual selected scheme, which are again hard to value. Other schemes that reduce those damages would be much more expensive, and have other different local costs. It's all very difficult. Do nothing and you stil have a very busy traffic-jam-ridden road running close visible/audible from Stonehenge, which is not nice. You could just close the road, but the large volume of traffic would have to go somewhere.
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