Safe Speed Forums

May seem an obvious question, but is it?

It's not very well explained in the Highway Code, but...
I originally understood that a dual carriageway was a road with 2 lanes in each direction.
I was then told that this was incorrect, that a dual carriageway is a road with a central reservation, and people had been prosecuted for doing 70 mph on a 'Four lane highway'.

So, 2 questions:
1 A central reservation consists of what? A central barrier - yes, a row of trees, bushes shrubs - yes, a grass verge or small bank without a barrier - ???, a marked hash area on the road between lanes???

2 What if it's one lane in each direction, but with a barrier between the lanes? I wasn't sure whether this would exist or not, and I couldn't think of an example previously. However, I was on the A66 between Scotch Corner and Penrith this weekend - and there it was (For a short section at least). So what is the speed limit here? Dual carriageway or not?

Dual carriageways are marked by a central reserve - not to be confused by a short central island on a big junction. This has to be more than painted hatchings.

Barriers are common but not mandatory (A525 between St Asaph and Rhyl springs to mind). You can have 2 lanes in each direction without a central reserve (A556 between the M6 and M56 for example).

One lane in each direction with a barrier would be a dual carriageway.

Have I understood you correctly in saying that the A525 and A556 are dual carriageways without a barrier. If so, how do you know it's a dual carriageway?



In which case, why did a sign on this section say "Dual carriageway ahead"?

No. The A525 is, the A556 isn't.



No idea.

Another point - what's the difference between a d-c and an s-c with a long central island? How short does an island have to be before we should regard the road as s-c and how long does it have to be before we can treat it as a d-c? And wouldn't it be a lot easier if they simply signed everything properly so we could go by that instead?

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Make everything as simple as possible, but not simpler - Einstein

Some Legal definition for your consumption.

Part IV of Schedule 6 to the The Road Traffic Regulation Act 1984 provides a definition of dual-carriageway.


While Regulation 4 of the Traffic Signs Regulations and General Directions 2002 defines a central reservation.


I believe that the minimum definition of a central reservation would be if it separated the carriages by means of a solid bounded continuing chevronned area which was designed specifically as a carriageway separator, and not as a specific hazard protection.

This is only my interpretation however.

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Fixed ideas are like cramp, for instance in the foot, yet the best remedy is to step on them.

Ian

So do double white lines count as "land" between the two carriageways.



Hell...if you don't know, what hope for the rest of us...

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Speed camera policy Kills

I'd count that as separation for a specific hazard.


The definition in my above post is as per legislation, In the area I work I have no problem defining the roads.

Definition wise there is no need for any raised barrier or change of surface, or Armco barrier to define a central reservation, so the description I've given would seem to make sense.



I know all I need to know, Any more knowledge and, Alexei Sayle wise, I might just forget how to walk.

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Fixed ideas are like cramp, for instance in the foot, yet the best remedy is to step on them.

Ian

The road where I am being accused of doing 70 in a 60 is separated by a 200M chevroned area which finishes with a ghost island.

Is this a dual carriageway?

The A303 Ilminster bypass is apparently a 60 mph but is separated by painted markings only. The Somerset Scamera partnership have now said that they will treat it as a 70 mph limit because it is so confusing.

Wiltshire however are insisting that it is a 60mph.

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If you're right, did your heels in
If you're wrong, admit it!

Sink the scameraships
Give us back our Police Force

No, a dual carriageway has to have some kind of physical central divide - road paint alone does not make a road dual. As this does seem to cause a lot of confusion it would be worthwhile including a definition in the Highway Code.


It would make sense to put "60" repeaters along this road to clarify the speed limit, as has been done on the A556 between M6 J19 and Northwich.

See this page showing the road and explaining the limit on the Cheshire scameraship website.

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"Show me someone who says that they have never exceeded a speed limit, and I'll show you a liar, or a menace." (Austin Williams - Director, Transport Research Group)

Any views expressed in this post are personal opinions and may not represent the views of Safe Speed

It would make sense to put repeaters on all roads to eliminate the need for ridiculous threads like this one. If the locals can't work it out what hope does a foreigner have?

Two enforcement policies on the same bit of road. And they wonder why people don't take them seriously as far as road safety goes?

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Make everything as simple as possible, but not simpler - Einstein

Can you help as to where that is precisely defined Peter, as the definition given in the regs is a little woolly, defining it as

(a) any land between the carriageways of a road comprising two carriageways; or
(b) any permanent work (other than a traffic island) in the carriageway of a road

which separates the carriageway.

Thanks,

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Fixed ideas are like cramp, for instance in the foot, yet the best remedy is to step on them.

Ian

I don't have any further knowledge beyond that - but I would interpret "any land" as meaning a strip of territory that is different in character from the carriageway, such as a grass strip. Central hatching would be on the carriageway, rather than dividing two carriageways.

_________________
"Show me someone who says that they have never exceeded a speed limit, and I'll show you a liar, or a menace." (Austin Williams - Director, Transport Research Group)

Any views expressed in this post are personal opinions and may not represent the views of Safe Speed

Not sure if this will help but as I understand it a dual carriageway is a road with either a raised portion of land seperating the traffic travelling in each direction or a fixed barrier.

If it's just raised land the speed limit is 60mph

If it's a fixed barrier the speed limit is 70mph.

These speed limits only apply if no other speed limit is signed and the national speed limit sign is used to indicate that either 60 or 70mph is the limit.

If so then I speed more often than I knew - I've always treated them as exactly the same. Any source for that? I have to say it doesn't sound right - if there was going to be different NSLs for different types of dual carriageway that really should be in the Highway Code. While the HC is a bit vague on what makes a d-c it seems to be clear on NSLs. It also doesn't seem like a good definition in principle (though would probably be alright in practice). What if it's raised kerb height but separates the carriageways by 200 yards? I doubt there's anywhere quite like that , but in principle if it did exist it probably would be better than a barrier. The other question that comes to mind is if the lower limit for an un-barriered d-c is purely because of the risk of cross-over collisions, is it really going to make any difference? I'd imagine a cross over crash is going to be about as nasty at 60 as it is at 70. And if Somerset Scammers really are treating the single carriageway non-barriered Ilminster bypass section of the A303 as d-c for enforcement they've really got it wrong if they're treating it as 70. Mind you, being scammerati they're anyway.

Going off at a slight tangent, anyone know the A320 between St Peter's Hospital in Chertsey and J11 of the M25? For those who don't it's a dual carriageway that used to have a central reservation consisting only of a shallow gravel filled ditch between the carriageways. No raised kerbs or anything, just a few feet of gravel between the two streams of traffic, and I'm pretty sure it was NSL at the time. A few years ago they improved it by putting armco down the length of the central reservation - which might have been because you got the occasional muppet doing a U turn across the gravel when the road bunged up in the rush hour. So the road became safer, but around the same time the limit dropped to , which predictably enough seems widely ignored when it's safe to go faster (a lot of the time in other words). I'm surprised I've never seen a talivan in the layby there.

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Make everything as simple as possible, but not simpler - Einstein

Are you talking about the 4-lane single carriageway bit between M6 and M56?

There is a problem with these signs since (AFAIK) the speed limit for certain HGVs is 50mph.

It is on my route to the office and yes, I do ignore the ludicrous limit when traffic permits.

Even more nonsensical is the Staines bypass between Crooked Billet and Ashford. That was NSL D/C without barriers but they reduced it to 50 because of a few (2-3) crossover collisions in the space of a few years. Then they improved the sightlines by cutting back vegetation in the central reservation; then they installed barriers. Result - a perfectly good, safe stretch of semi-rural D/C; no houses or other buildings, junctions, driveways, pavements or pedestrians and very few cyclists, but still limited to 50. Yet - by way of absurd contrast, the remaining stretch of the A308 up to Sunbury Cross (or just before) remains 50 limit even though it is heavily built-up and has multiple junctions, driveways, shops, traffic lights, pedestrians etc.

The 4-lane single-carriageway extends further south than the M6 as well.

I think you'll find that the speed limit for HGVs is 40, not 50 - it's the same limit as for any other single-carriageway road.