Smart Motorways

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Horse
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Re: Smart Motorways

Postby Horse » Thu Jan 31, 2019 8:48 pm

kfae8959 wrote:
martine wrote:Smart motorways often have average speed cameras...


Which ones?

David


If they're the (often yellow) ones on the posts, pointing towards the sign gantries, then they're 'spot' speed. Average speed cameras are usually one camera per lane, on separate posts, they'll be at regular intervals and at junction slips.

T&C's apply: this advice is to be considered little more than guesswork and should not be quoted as definitive.
Your 'standard' is how you drive alone, not how you drive during a test.

kfae8959
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Re: Smart Motorways

Postby kfae8959 » Fri Feb 01, 2019 12:01 am

I've seen plenty of average speed enforcement in the roadworks to convert motorways to "managed" or "smart". I don't think I've come across it on completed stretches.

Your point about lower speed limits on congested stretches increasing time separation interests me. I've noticed what feels like higher traffic density, with smaller distance separation, when lower limits were in force, although what is cause and what effect I cannot know. Next time I'm on the M6 I'll see what I notice about time gaps.

David

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Strangely Brown
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Re: Smart Motorways

Postby Strangely Brown » Fri Feb 01, 2019 6:36 am

AIUI, the cameras in use on "smart" motorways are HADECS3. Highways Agency Digital Enforcement Camera System 3. They are usually grey and alongside the gantries. AFAIK, they are "always on" but I do not know exactly what enforcement they provide or to what tolerance.

This may help.

https://www.speedcamerasuk.com/hadecs-3.htm

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Horse
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Re: Smart Motorways

Postby Horse » Fri Feb 01, 2019 7:38 am

Unlike black cats at night, the grey ones are sometimes yellow :)
Your 'standard' is how you drive alone, not how you drive during a test.

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Horse
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Re: Smart Motorways

Postby Horse » Fri Feb 01, 2019 7:45 am

kfae8959 wrote:Your point about lower speed limits on congested stretches increasing time separation interests me. I've noticed what feels like higher traffic density, with smaller distance separation, when lower limits were in force, although what is cause and what effect I cannot know. Next time I'm on the M6 I'll see what I notice about time gaps.


It's simple maffs innit? If the number of vehicles in a lane remains constant, then the distance between them must too. If they're traveling more slowly, then that distance will be travelled more slowly, so a greater time separation.

However, AFAIK the lower limits 'should' only be set when traffic volume increases, so that might result in what you report. Effect and cause, tomaydo tomato.
Your 'standard' is how you drive alone, not how you drive during a test.

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exportmanuk
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Re: Smart Motorways

Postby exportmanuk » Fri Feb 01, 2019 8:05 am

My Observations
Normal motorways
Lane 1 mainly convoys of trucks usually 0.25 second gap whilst they slipstream driving on the limiter at 56 MPH
lane 2 1 car driving at 45 miles per hour in from 30 seconds behind 20 cars all less than a second between them Guys at the back just caught up with them at 90 mph and had to brake hard as he had not noticed them He will stay behind in lane two until all the cars in front move out of his way then remaining in lane 2 he will accelerate to 90 again to catch the next convoy.
Lane 3 all doing 80 but wanting to do more less than 0.5 second gap

(Not so) Smart motorways and average speed camera motorways
Lane 1 mainly convoys of trucks usually 0.25 second gap whilst they slipstream driving on the limiter at 56 MPH
lane 2 1 car driving at 45 miles per hour in from 30 seconds behind 20 cars all less than a second between them Guys at the back just caught up with them at 90 mph but slowing down for the speed cameras and had to brake hard as he had not noticed the queue in front of him. He will stay behind in lane two until all the cars in front move out of his way then remaining in lane 2 he will accelerate to 90 again to catch the next convoy.
Already has 18 points on his license
Lane 3 all doing 5 mph more than the posted limit but wanting to do more less than 0.5 second gap
Andrew Melton
Manchester 500

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Horse
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Re: Smart Motorways

Postby Horse » Fri Feb 01, 2019 10:20 am

No-one in lane 4 on your smart motorway?
Your 'standard' is how you drive alone, not how you drive during a test.

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Horse
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Re: Smart Motorways

Postby Horse » Fri Feb 01, 2019 6:59 pm

Horse wrote:
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! :)


Any thoughts test, SB?
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 » Fri Feb 01, 2019 7:51 pm

I refer the honourable gentleman to my earlier response.

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Horse
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Re: Smart Motorways

Postby Horse » Sat Feb 02, 2019 8:14 am

Strangely Brown wrote:I refer the honourable gentleman to my earlier response.


So how would the non-t.i.c part be achieved?
Your 'standard' is how you drive alone, not how you drive during a test.


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