Smart Motorways

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martine
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Smart Motorways

Postby martine » Wed Jan 30, 2019 6:03 pm

So Peter Rodger from IAM RoadSmart and Edmund King from the AA was just on BBC R4 'PM' program discussing Smart Motorways. https://www.bbc.co.uk/sounds/play/m000281y 48 mins in.

Edmund said the M42 (the original smart motorway) has safety refuges every 600-800 yards but subsequent motorways are much more spread out - 2.5km or 1.5m.

What do people here think of Smart Motorways?
Last edited by martine on Wed Jan 30, 2019 6:50 pm, edited 1 time in total.
Martin - Bristol Advanced Motorists: IMI National Observer, Group Secretary, Masters (dist), DSA: ADI, Fleet, RoSPA (Dip)

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jont-
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Re: Smart Motorways

Postby jont- » Wed Jan 30, 2019 6:47 pm

It would be "smarter" to get drivers off the roads who can't follow correct lane discipline.

martine
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Re: Smart Motorways

Postby martine » Wed Jan 30, 2019 6:51 pm

jont- wrote:It would be "smarter" to get drivers off the roads who can't follow correct lane discipline.

The main point raised during the interviews was the relatively long gap between safety refuges on newer Smart Motorways. I've put a link in the original post so people can listen if they wish.
Martin - Bristol Advanced Motorists: IMI National Observer, Group Secretary, Masters (dist), DSA: ADI, Fleet, RoSPA (Dip)

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Strangely Brown
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Re: Smart Motorways

Postby Strangely Brown » Wed Jan 30, 2019 7:24 pm

I think I remember figures from Highways England on Radio4 recently and they showed that the accident rate on "smart" motorways is higher than on traditional variety ?

I think they are a fantastically expensive solution looking for a problem.

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Horse
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Re: Smart Motorways

Postby Horse » Wed Jan 30, 2019 8:01 pm

Strangely Brown wrote:I think they are a fantastically expensive solution looking for a problem.


They're a way of adding lane capacity, with the enforced variable speed limits reduce speeds to improve the time separation between vehicles.

If you can suggest another way of achieving those aims without using additional land alongside the carriageway (in some places that's simply not possible), then speak up! :)
Your 'standard' is how you drive alone, not how you drive during a test.

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Strangely Brown
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Re: Smart Motorways

Postby Strangely Brown » Wed Jan 30, 2019 8:11 pm

Remove traffic by removing drivers who don’t deserve their licence.

Tongue only partly in cheek.

kfae8959
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Re: Smart Motorways

Postby kfae8959 » Wed Jan 30, 2019 9:57 pm

Horse wrote:They're a way of adding lane capacity, with the enforced variable speed limits reduce speeds to improve the time separation between vehicles.


Do the variable speed limits achieve that, though? Or, more precisely, does the way they are enforced achieve that?

Behaviour I have observed includes:
- drivers failing to use lane 1 of 4 altogether (so I can use it and sail past hundreds)
- assuming the enforcement cameras are active even when no limit is displayed on the gantries - or just panic braking in response to distance markings on the road!
- ignoring displayed limits (perhaps in hired vehicles or others whose drivers believe they will not be summonsed)

I adopt a "burn and coast" approach to try to maximise progress - I'll move to lane n, drive between the gantries at an indicated 70 - 75, then lift to meet the posted limit at each point of possible enforcement. That this option is left open seems to me to undermine the idea behind the scheme altogether. Why is there not average speed enforcement?

Does anyone know where I can find data on prosecutions for exceeding smart motorway temporary speed limits?

David

martine
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Re: Smart Motorways

Postby martine » Thu Jan 31, 2019 9:28 am

kfae8959 wrote:[...I adopt a "burn and coast" approach to try to maximise progress - I'll move to lane n, drive between the gantries at an indicated 70 - 75, then lift to meet the posted limit at each point of possible enforcement. That this option is left open seems to me to undermine the idea behind the scheme altogether. Why is there not average speed enforcement?

Smart motorways often have average speed cameras...your 'burn and coast' method could still trigger them.

Does anyone know where I can find data on prosecutions for exceeding smart motorway temporary speed limits?

I know many thousands of motorists have been prosecuted (or offered an education course) for exceeding the smart motorway limits...a quick google showed individual prosecutions but there must be a summary somewhere.
Martin - Bristol Advanced Motorists: IMI National Observer, Group Secretary, Masters (dist), DSA: ADI, Fleet, RoSPA (Dip)

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Horse
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Re: Smart Motorways

Postby Horse » Thu Jan 31, 2019 2:57 pm

kfae8959 wrote:
Horse wrote:They're a way of adding lane capacity, with the enforced variable speed limits reduce speeds to improve the time separation between vehicles.


Do the variable speed limits achieve that, though? Or, more precisely, does the way they are enforced achieve that?


Enforcement won't change actual behaviour at the moment that it's taking place, it's the compliance (or fear of being caught) that makes the difference.

That compliance will only be for the number of vehicles on that stretch of road at that time, which will have a direct relationship to the physical separation distance between them. Slower speeds will result in a longer time interval between the vehicles, so ought to be safer (time to react, shorter braking distances).

Lower speeds might also reduce bunching and potentially acceleration and braking, such as:


Also (although AFAIK it's not being done at the moment), there may be benefits from enforced lower speed limits on reducing air pollution.
Your 'standard' is how you drive alone, not how you drive during a test.

kfae8959
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Re: Smart Motorways

Postby kfae8959 » Thu Jan 31, 2019 6:11 pm

martine wrote:Smart motorways often have average speed cameras...


Which ones?

David


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