‘Dual Carriageway Ahead’ Signs

[Conekicker]

Confirmation, there is no start of dual carriageway sign and some dopy drivers may not notice.

If that were the case, such signs would be present at the start of every dual carriageway, which given that "Start of dual carriageway" signs don't exist, makes "confirmation" an incorrect assumption.

Most start of dual carriageways are obvious so don't need to tell dopy drivers. I was about to say you don't need one here but then I saw one. Not one here

As with almost all traffic signs, there's no legal requirement to actually install them.

[Glenn A]

The A66 has them 2 miles before the start of each section. It's maybe to remind drivers not to overtake on the dangerous S2 sections between Penrith and Scotch Corner and not to treat the Embleton by pass like a race track when it's quiet. Also being stuck behind a tractor at 10 mph, the signs remind you Farmer Palmer can be overtaken in 1 or 2 miles safely.

[KeithW]

The A66 has them 2 miles before the start of each section. It's maybe to remind drivers not to overtake on the dangerous S2 sections between Penrith and Scotch Corner and not to treat the Embleton by pass like a race track when it's quiet. Also being stuck behind a tractor at 10 mph, the signs remind you Farmer Palmer can be overtaken in 1 or 2 miles safely.

With rising traffic on the A66 there was a rapid rise in accidents onS2 sections. In the last 10 years there have been 70 people killed on the A66 , the problem is not just that its S2 but the number of flat junctions like this one.
https://www.google.co.uk/maps/@54.47638 ... 8192?hl=en

[jnty]

How about this "2 miles to dual carriageway" sign situated approximately 500m before a dual carriageway?


https://maps.app.goo.gl/PwJTdGSR1Esk7jy26

[KeithW]

How about this "2 miles to dual carriageway" sign situated approximately 500m before a dual carriageway?

https://maps.app.goo.gl/PwJTdGSR1Esk7jy26

They are short sections of dual carriageway on the Berwick bypass for junctions, there are a lot of them along the A1, it can be useful to let one or 2 cars past a slow moving load but that is not the main purpose .

[SteelCamel]

How about this "2 miles to dual carriageway" sign situated approximately 500m before a dual carriageway?

https://maps.app.goo.gl/PwJTdGSR1Esk7jy26

They are short sections of dual carriageway on the Berwick bypass for junctions, there are a lot of them along the A1, it can be useful to let one or 2 cars past a slow moving load but that is not the main purpose .

Yes, looks to me like the intent is that the right lane is for passing traffic slowing for the turn (or joining from the turn), not slow vehicles on the A1. To further discourage overtaking, there's a speed camera at the end! So although this is technically a dual carriageway, in practice it's more of an extended traffic island.
There's another section at the next junction, but the "2 miles" is clearly counting to the A1167 roundabout where a 2.5 mile stretch of dual carriageway starts.

[Chris Bertram]

... the signs remind you Farmer Palmer can be overtaken in 1 or 2 miles safely.

Get orf moy laaaand!

[jnty]

How about this "2 miles to dual carriageway" sign situated approximately 500m before a dual carriageway?

https://maps.app.goo.gl/PwJTdGSR1Esk7jy26

They are short sections of dual carriageway on the Berwick bypass for junctions, there are a lot of them along the A1, it can be useful to let one or 2 cars past a slow moving load but that is not the main purpose .

Yes, looks to me like the intent is that the right lane is for passing traffic slowing for the turn (or joining from the turn), not slow vehicles on the A1. To further discourage overtaking, there's a speed camera at the end! So although this is technically a dual carriageway, in practice it's more of an extended traffic island.
There's another section at the next junction, but the "2 miles" is clearly counting to the A1167 roundabout where a 2.5 mile stretch of dual carriageway starts.

The 2+1 section continues on so I think some overtaking is expected. The speed camera is what drew my attention to this section, as I happily went past it at a legal 70 once only to immediately see the road go down to S2+1 and wonder if I'd misinterpreted the layout. It's certainly a bit of an odd one.

[swissferry]

Glad the car I was overtaking on the former short D2 (now D1) on the A9 near Pitlochry didn't accelerate when there was a Talivan at the junction. Immediately afterwards I wondered if the police regarded the limit as 60 (long traffic island) or 70 (short dual carriageway). Passed at 70 and never heard from them.

[jnty]

Glad the car I was overtaking on the former short D2 (now D1) on the A9 near Pitlochry didn't accelerate when there was a Talivan at the junction. Immediately afterwards I wondered if the police regarded the limit as 60 (long traffic island) or 70 (short dual carriageway). Passed at 70 and never heard from them.

The "experimental" 50mph S2 HGV limit ends and restarts before/after this section, so it's obviously regarded as D1 by the designer of that scheme.

It's now within an average speed camera section and I always wonder how they factor in the D1 bit. You could presumably do the maths, but I wonder if to keep things simple (and comply with relevant regulations?) they time the whole section as if it were a 70mph limit or just don't bother enforcing on it at all.

[MotorwayGuy]

Glad the car I was overtaking on the former short D2 (now D1) on the A9 near Pitlochry didn't accelerate when there was a Talivan at the junction. Immediately afterwards I wondered if the police regarded the limit as 60 (long traffic island) or 70 (short dual carriageway). Passed at 70 and never heard from them.

The "experimental" 50mph S2 HGV limit ends and restarts before/after this section, so it's obviously regarded as D1 by the designer of that scheme.

It's now within an average speed camera section and I always wonder how they factor in the D1 bit. You could presumably do the maths, but I wonder if to keep things simple (and comply with relevant regulations?) they time the whole section as if it were a 70mph limit or just don't bother enforcing on it at all.

I'm not sure legally what the deal is with speed limit changes within average speed zones, normally you'd have a camera stalk either side of the change but as the section of dual carriageway and northern section of S2 are so short it'd be pointless to do so. If they have calculated it in, what point does the 70 become 60? One would assume where the central separation ends, but in this case HGVs would have to slow down for the short sections between the experimental signs!

[jnty]

Glad the car I was overtaking on the former short D2 (now D1) on the A9 near Pitlochry didn't accelerate when there was a Talivan at the junction. Immediately afterwards I wondered if the police regarded the limit as 60 (long traffic island) or 70 (short dual carriageway). Passed at 70 and never heard from them.

The "experimental" 50mph S2 HGV limit ends and restarts before/after this section, so it's obviously regarded as D1 by the designer of that scheme.

It's now within an average speed camera section and I always wonder how they factor in the D1 bit. You could presumably do the maths, but I wonder if to keep things simple (and comply with relevant regulations?) they time the whole section as if it were a 70mph limit or just don't bother enforcing on it at all.

I'm not sure legally what the deal is with speed limit changes within average speed zones, normally you'd have a camera stalk either side of the change but as the section of dual carriageway and northern section of S2 are so short it'd be pointless to do so. If they have calculated it in, what point does the 70 become 60? One would assume where the central separation ends, but in this case HGVs would have to slow down for the short sections between the experimental signs!

Yes, I've wondered the same. I generally treat the end of HGV limit signs as the start of the D2 70 limit along the whole road but there is definitely a lot of "slack" in their positioning.

[Glenn A]

The A66 has them 2 miles before the start of each section. It's maybe to remind drivers not to overtake on the dangerous S2 sections between Penrith and Scotch Corner and not to treat the Embleton by pass like a race track when it's quiet. Also being stuck behind a tractor at 10 mph, the signs remind you Farmer Palmer can be overtaken in 1 or 2 miles safely.

With rising traffic on the A66 there was a rapid rise in accidents onS2 sections. In the last 10 years there have been 70 people killed on the A66 , the problem is not just that its S2 but the number of flat junctions like this one.
https://www.google.co.uk/maps/@54.47638 ... 8192?hl=en

I was driving on there yesterday and it's a stressful experience, made worse by the flat junctions, at grade junctions and people overtaking just before the D2 sections end. Not quite on topic, but the average speed cameras at Kirby Thore and some of the S2 sections being downgraded to 50 mph must have made a difference.

[ais523]

It's now within an average speed camera section and I always wonder how they factor in the D1 bit. You could presumably do the maths, but I wonder if to keep things simple (and comply with relevant regulations?) they time the whole section as if it were a 70mph limit or just don't bother enforcing on it at all.

I don't know how this particular section is done, but if you wanted to do the maths, it would be incredibly simple: think of it not in terms of speed but in terms of journey time. If you get from A to B in a shorter time than a hypothetical car driving at the speed limit would have been able to get from A to B, you must have been speeding somewhere along the route. This reasoning works no matter what the speed limit is or how often it changes (just imagine your hypothetical comparison car is always moving exactly at the speed limit and accelerates/decelerates instantly when it changes) – the only requirement is that there isn't a faster alternative route between the same two points.

[jnty]

It's now within an average speed camera section and I always wonder how they factor in the D1 bit. You could presumably do the maths, but I wonder if to keep things simple (and comply with relevant regulations?) they time the whole section as if it were a 70mph limit or just don't bother enforcing on it at all.

I don't know how this particular section is done, but if you wanted to do the maths, it would be incredibly simple: think of it not in terms of speed but in terms of journey time. If you get from A to B in a shorter time than a hypothetical car driving at the speed limit would have been able to get from A to B, you must have been speeding somewhere along the route. This reasoning works no matter what the speed limit is or how often it changes (just imagine your hypothetical comparison car is always moving exactly at the speed limit and accelerates/decelerates instantly when it changes) – the only requirement is that there isn't a faster alternative route between the same two points.

The problem with doing that obviously isn't the theory of working out the appropriate journey time for each length, which involves high school level maths, but defining in a legally watertight way what those lengths are. Presumably the authorities do not want to be drawn into a court case where every traffic island is measured to the metre and expert witnesses argue about distances round a curve. I would imagine that if they do try to set the journey time appropriately then very generous definitions for where the D1 starts and ends are chosen.

A heterogeneously limited section also seems like the sort of thing which might either not be provided for or expressly forbidden by the relevant regulations.

[orudge]

It's now within an average speed camera section and I always wonder how they factor in the D1 bit. You could presumably do the maths, but I wonder if to keep things simple (and comply with relevant regulations?) they time the whole section as if it were a 70mph limit or just don't bother enforcing on it at all.

I haven't checked the specifics here, but let's assume the average speed camera section is 10 miles long, that 0.4 miles of it is 70mph D1 (which seems to be roughly how long that section is), and 9.6 miles is 60mph S2. If you did precisely the speed limit for the entire length, you'd get an average speed of 60.4mph, which presumably is well within the tolerance the cameras have.

If you were doing 67mph on the S2 and 78mph on the D2 (assuming average speed cameras have the same tolerance that many other cameras are meant to have), then your average speed would still only be 67.44mph.

Of course, if the distance between cameras is just 5 miles, then the figures will be a bit different, but certainly on the A90, the average speed cameras are generally spaced fairly infrequently.

[FtoE]

Glad the car I was overtaking on the former short D2 (now D1) on the A9 near Pitlochry didn't accelerate when there was a Talivan at the junction. Immediately afterwards I wondered if the police regarded the limit as 60 (long traffic island) or 70 (short dual carriageway). Passed at 70 and never heard from them.

I’ve often wondered what that short section was for and idly wondered if it was some kind of emergency lane in case someone pulled out of the junction ahead of you. A few months back that’s exactly what I saw happen - a Dutch car pulled out turning left (north) and the car ahead of me used the lane to avoid a collision.
(I’m sure that’s not its intended purpose but it saved a crash that day)

[AndyB]

A SPECS system can have several speed limits between the first and last cameras, but the three things you will not find between cameras used for timing are speed limit changes, traffic lights and any variation on a give way line.

No speed limit changes because enforcement decisions can’t really be taken if you can’t tell which speed limit has been exceeded, and there is no point timing traffic which at most of times of day has to slow down for the junction so that their average speed is nowhere near the speed limit, let alone in excess. They are very much set up for flying traffic.

[Glenn A]

... the signs remind you Farmer Palmer can be overtaken in 1 or 2 miles safely.

Get orf moy laaaand!

Ho, ho, you won't get past me for the next 10 miles( a common problem on the A595).

[MotorwayGuy]

This has to be one of the strangest ones I've come across, and it looks brand new. Looking back it appears they have replaced a very old faded sign with this new one, why it was deemed necessary to replace it and the pole rather than just remove it is a bit baffling, especially none of the other intersecting roads have them or even no entry signs.