New kent " Turbo Roundabout" with "colour coded" routes

[Debaser]

I do like the roundabout-style arrow indications on the road. I think those are much better than the current arrangement of "left for left, ahead for just about anything else". They seem quite common in Europe and I don't think they're particularly confusing. Saw them in the US too on the odd roundabout.

I agree, pity the DfT doesn't. I've not seen an authorisation for them yet either which could be difficult for the highway authority if someone cocks up the basic task of following road markings.

We are so stuck in our ways in this country and there are supposed "policy experts" that know very little but seem to think exceptionalism is equivalent to being good. This is why we don't have signs the rest of Europe copes with, we still use weird excuses for not using turn arrows and segregation of vehicles, and why our roundabouts are usually complete disasters.

But if we mark right turn arrows on the carriageway on the approach to roundabouts drivers will automatically turn right onto the circulatory and there'll be mayhem! Never mind the bloody great 606 turn left arrow and 515 chevrons pointing to left, right in front of them.

[Bryn666]

I do like the roundabout-style arrow indications on the road. I think those are much better than the current arrangement of "left for left, ahead for just about anything else". They seem quite common in Europe and I don't think they're particularly confusing. Saw them in the US too on the odd roundabout.

I agree, pity the DfT doesn't. I've not seen an authorisation for them yet either which could be difficult for the highway authority if someone cocks up the basic task of following road markings.

We are so stuck in our ways in this country and there are supposed "policy experts" that know very little but seem to think exceptionalism is equivalent to being good. This is why we don't have signs the rest of Europe copes with, we still use weird excuses for not using turn arrows and segregation of vehicles, and why our roundabouts are usually complete disasters.

But if we mark right turn arrows on the carriageway on the approach to roundabouts drivers will automatically turn right onto the circulatory and there'll be mayhem! Never mind the bloody great 606 turn left arrow and 515 chevrons pointing to left, right in front of them.

I'd love to know who thinks those right turn arrows on the ground cause such a problem, if people can somehow turn right into a roundabout then that's a design problem because the entry deflection is clearly beyond wrong.

Maybe if we didn't still insist giant circulatory carriageways were viable junction ideas - the rest of the world is rapidly moving away from 40+ mph circles, except dear old exceptionalist Britain.

[SteelCamel]

I'd love to know who thinks those right turn arrows on the ground cause such a problem, if people can somehow turn right into a roundabout then that's a design problem because the entry deflection is clearly beyond wrong.

Also if that's really the issue, why can't we paint different arrows? I would have thought an arrow shaped like a backward question mark would make it quite clear that you should turn right by going left around the roundabout. You could even have a straight arrow with a kink for "ahead", in case anyone thinks they should drive over the island rather than going around the left side.

[Conekicker]

Right turn arrows on the approach to roundabouts you say?

Traffic Signs Manual Chapter 5 says (my highlighting):

6.7.2. It is possible that the use of a right-turn arrow on the approach to a roundabout might encourage some drivers, particularly those from overseas, to turn the wrong way into the circulatory carriageway. However, in most situations the clockwise direction of circulation should be apparent. Where the right-hand lane is dedicated to right-turning traffic, a right-turn arrow should not present any difficulties and will ensure appropriate use of the lane. There will be some situations, particularly where the roundabout has spiral markings (see 6.6.7) or is controlled by traffic signals, where it is likely to be more appropriate to use ahead arrows with destinations for all approach lanes.

[Bryn666]

Right turn arrows on the approach to roundabouts you say?

Traffic Signs Manual Chapter 5 says (my highlighting):

6.7.2. It is possible that the use of a right-turn arrow on the approach to a roundabout might encourage some drivers, particularly those from overseas, to turn the wrong way into the circulatory carriageway. However, in most situations the clockwise direction of circulation should be apparent. Where the right-hand lane is dedicated to right-turning traffic, a right-turn arrow should not present any difficulties and will ensure appropriate use of the lane. There will be some situations, particularly where the roundabout has spiral markings (see 6.6.7) or is controlled by traffic signals, where it is likely to be more appropriate to use ahead arrows with destinations for all approach lanes.

The previous iteration of DMRB (TD16/07) of course had a mandatory black box:

8.28 The use of right pointing arrows on lane dedication signs or as markings on the road is not permitted on roundabout approaches (except at mini-roundabouts). This is to avoid confusing drivers, particularly those from overseas, over which way to proceed around the roundabout. Where a right hand lane is dedicated to a specific destination, it should be associated with an ahead arrow on the approach. A right pointing arrow may be used on the circulatory carriageway.

This was just another example of how out of touch the DMRB is with reality. Regrettably this guidance is now taken as gospel by many designers who aren't bothered that Chapter 5 says otherwise. You still get "checkers" in NH who'll kick off about right arrows on roundabouts.

[Peter Freeman]

Also if that's really the issue, why can't we paint different arrows? I would have thought an arrow shaped like a backward question mark would make it quite clear that you should turn right by going left around the roundabout. You could even have a straight arrow with a kink for "ahead", in case anyone thinks they should drive over the island rather than going around the left side.

Shapes like this?
https://www.signspotters.hobbiesplus.co ... 020010.JPG

(edit: link corrected)

[Conekicker]

Right turn arrows on the approach to roundabouts you say?

Traffic Signs Manual Chapter 5 says (my highlighting):

6.7.2. It is possible that the use of a right-turn arrow on the approach to a roundabout might encourage some drivers, particularly those from overseas, to turn the wrong way into the circulatory carriageway. However, in most situations the clockwise direction of circulation should be apparent. Where the right-hand lane is dedicated to right-turning traffic, a right-turn arrow should not present any difficulties and will ensure appropriate use of the lane. There will be some situations, particularly where the roundabout has spiral markings (see 6.6.7) or is controlled by traffic signals, where it is likely to be more appropriate to use ahead arrows with destinations for all approach lanes.

The previous iteration of DMRB (TD16/07) of course had a mandatory black box:

8.28 The use of right pointing arrows on lane dedication signs or as markings on the road is not permitted on roundabout approaches (except at mini-roundabouts). This is to avoid confusing drivers, particularly those from overseas, over which way to proceed around the roundabout. Where a right hand lane is dedicated to a specific destination, it should be associated with an ahead arrow on the approach. A right pointing arrow may be used on the circulatory carriageway.

This was just another example of how out of touch the DMRB is with reality. Regrettably this guidance is now taken as gospel by many designers who aren't bothered that Chapter 5 says otherwise. You still get "checkers" in NH who'll kick off about right arrows on roundabouts.

Sadly, CD 116 is at variance with Chapter 5, (and thus, importantly, DfT's views on the subject), as it prohibits the use of a right turn arrow on the approach in section 3.27. Ooops.

Something for someone to bring to the attention of the owner of CD 116?

[SteelCamel]

Also if that's really the issue, why can't we paint different arrows? I would have thought an arrow shaped like a backward question mark would make it quite clear that you should turn right by going left around the roundabout. You could even have a straight arrow with a kink for "ahead", in case anyone thinks they should drive over the island rather than going around the left side.

Shapes like this?
https://www.signspotters.hobbiesplus.co ... 020010.JPG

Yes, that's pretty much the shapes I had in mind, though I was thinking of arrows painted on the road rather than on a sign.

Though it seems that painted arrows in Victoria don't have the kink - there's a simple right-pointing arrow, and not even a "turn left" sign, just chevrons - yet it seems drivers are able to understand that they need to go around the far side of the roundabout.

[Peter Freeman]

Shapes like this?
https://www.signspotters.hobbiesplus.co ... 020010.JPG

Yes, that's pretty much the shapes I had in mind, though I was thinking of arrows painted on the road rather than on a sign.

Though it seems that painted arrows in Victoria don't have the kink - there's a simple right-pointing arrow, and not even a "turn left" sign, just chevrons - yet it seems drivers are able to understand that they need to go around the far side of the roundabout.

Yes you're right: we have your desired shape, but on vertical, post-mounted signs, not painted on the road. The backwards-question-mark one for turn right might be hard to fit on the road in the lane width, though Kent intends to do it. FYI, AU has lower emphasis on road-painted direction signing than the UK, especially road numbers. I've a feeling that by the time you're in a busy roundabout, there's little spare attention to devote to reading the asphalt.

Our chevron placements on the central island, opposite an entry, are the same as UK. I think they're pretty obvious, and clear in their intent.

A class of AU roundabout signs that we have discussed previously on Sabre is this:
https://www.google.com.au/maps/@-34.927 ... &entry=ttu
These work really well, but are used only at places where correct advance laning is especially important. Generally, Vic and the rest of AU uses pole-mounted 'map type' signs on roundabout approaches, much like the UK's.

BTW, I meant to add above that the new turbo-rbt in Kent should include a sign, early on the southbound approach, that reads "Use either lane for London". And, BTW, I am optimistic about this improvement.

[freebrickproductions]

Shapes like this?
https://www.signspotters.hobbiesplus.co ... 020010.JPG

Yes, that's pretty much the shapes I had in mind, though I was thinking of arrows painted on the road rather than on a sign.

Though it seems that painted arrows in Victoria don't have the kink - there's a simple right-pointing arrow, and not even a "turn left" sign, just chevrons - yet it seems drivers are able to understand that they need to go around the far side of the roundabout.

Yes you're right: we have your desired shape, but on vertical, post-mounted signs, not painted on the road. The backwards-question-mark one for turn right might be hard to fit on the road in the lane width, though Kent intends to do it. FYI, AU has lower emphasis on road-painted direction signing than the UK, especially road numbers. I've a feeling that by the time you're in a busy roundabout, there's little spare attention to devote to reading the asphalt.

Our chevron placements on the central island, opposite an entry, are the same as UK. I think they're pretty obvious, and clear in their intent.

A class of AU roundabout signs that we have discussed previously on Sabre is this:
https://www.google.com.au/maps/@-34.927 ... &entry=ttu
These work really well, but are used only at places where correct advance laning is especially important. Generally, Vic and the rest of AU uses pole-mounted 'map type' signs on roundabout approaches, much like the UK's.

BTW, I meant to add above that the new turbo-rbt in Kent should include a sign, early on the southbound approach, that reads "Use either lane for London". And, BTW, I am optimistic about this improvement.

I do know at least some of the painted roundabout arrows here in the US do have the curved stems on them, such as the ones around this multi-lane roundabout in Chattanooga, TN:
https://www.google.com/maps/@35.0701216 ... ?entry=ttu

Per the MUTCD, both normal and curved stem arrows may be used on the approaches to roundabouts:

Section 3D.06 Arrow Pavement Markings for Roundabouts
Guidance:
01 Lane-use arrow pavement markings should not be used on single-lane approaches to circular intersections.
02 Lane-use arrows should be used on approaches to circular intersections with double left or double
right turns.
Standard:
03 Lane-use arrow pavement markings shall not be provided between a crosswalk and a wide dotted line
across the lane(s) entering the circular roadway.
Option:
04 Where lane-use arrows are used on the approaches to a roundabout, they may be either normal or curved-stem
(see Drawing F in Figure 3B-21).
05 An oval or circle may be used with the lane-use arrows to symbolize the central island (see Drawing F in
Figure 3B-21).
Guidance:
06 If lane-use arrows are used on the approaches to a roundabout, the style used should match the style of the
lane-use arrows (normal or curved-stem) used on the regulatory lane-use signs on the approach.
07 If lane-use arrow pavement markings are used within the circulatory roadway of multi-lane roundabouts,
normal lane-use arrows (see Section 3B.23 and Figure 3B-21) should be used.
Support:
08 Details and sizes of the standard and curved-stem arrows that can be used for circular intersections are
contained in the “Standard Highway Signs” publication (see Section 1A.05).

[Peter Freeman]

I do know at least some of the painted roundabout arrows here in the US do have the curved stems on them, such as the ones around this multi-lane roundabout in Chattanooga, TN:
https://www.google.com/maps/@35.0701216 ... ?entry=ttu

Per the MUTCD, both normal and curved stem arrows may be used on the approaches to roundabouts: ...

Those Chattanooga ones look great. So they do fit ok on the road.

Interestingly, they include a dot (circle) to suggest the rbt's central island, which is very good and ought to be included in AU's vertical versions. It is similar to the AU vertical signs that are like this:
https://www.google.com.au/maps/@-37.789 ... &entry=ttu

[Ruperts Trooper]

I'm a driver, not a road engineer - from a drivers' view, lane markings painted on the road don't work! When a junction is busy, the markings are hidden from view by all the traffic - when traffic is light it doesn't really matter which lane you're in (within reason).

I know that vertical signs on posts create a lot of visual clutter but that's better than road markings which don't work.

With road-painted lane markings it's far too common for strangers to be in the wrong lane, which causes annoyance to regulars and adds to congestion while these strangers sort themselves out - that's for car drivers, anyone in a bigger vehicle has even more difficulty negotiating the junction if they aren't familiar with it.

[Chris5156]

Yes, that's pretty much the shapes I had in mind, though I was thinking of arrows painted on the road rather than on a sign.

That’s exactly what is proposed at the roundabout under discussion - if you open the plans up thread you’ll see them.

[Peter Freeman]

Yes, that's pretty much the shapes I had in mind, though I was thinking of arrows painted on the road rather than on a sign.

That’s exactly what is proposed at the roundabout under discussion - if you open the plans up thread you’ll see them.

Amongst my praise for this improvement, I have one trivial niggle: the on-road-painted guidance doesn't correctly represent the roundabout. It has five arms, but the diagrams show only four. To include the extra would not be too difficult.

Does this matter? Not much, but it is possible that someone on approach might interpret the diagram literally and count the exits, thereby ending up for example in exit 2 when he actually wanted exit 3. Rather like counting exits when listening to your satnav's instructions. Other, more precise, roadside signage of course should prevent this error.

[AnOrdinarySABREUser]

<snip>

I know that vertical signs on posts create a lot of visual clutter but that's better than road markings which don't work.

<snip>

In my opinon, this turbo roundabout near the Ashford Designer Outlet gets it right, though it would be preferable if it were signed overhead rather than on the side per what you said. There should also be physical lane segregation to minimise confusion, but I think the chevrons are enough. Before the pandemic, the junction was a standard roundabout. This is one of those cheap but cheerful upgrades which major roundabouts across the country should receive, especially when dual carriageways are involved.

[Peter Freeman]

In my opinon, this turbo roundabout near the Ashford Designer Outlet gets it right, though it would be preferable if it were signed overhead rather than on the side per what you said. There should also be physical lane segregation to minimise confusion, but I think the chevrons are enough. Before the pandemic, the junction was a standard roundabout. This is one of those cheap but cheerful upgrades which major roundabouts across the country should receive, especially when dual carriageways are involved.

Yes, that looks good, and GMaps shows it as zero congestion. I agree that a conversion to turbo (or, closely related, spiral) of many poorly performing rbts would be in order.

Are there many turbo's in the UK now? I've never encountered one.

Observation: this one's not 'pure-turbo'. With only two circulatory lanes but three 2-lane exits, there remains some in-roundabout lane changing/crossing. That number of exit lanes should require 3-lane approaches and at least three single-lane circulatories. But that wouldn't be 'cheap-and-cheerful', and is unnecessary here. It works.

Digression, with apology: the LILO-GSJ about 600m east looks rather extravagant, in the circumstances!
https://www.google.com/maps/@51.1262864 ... ?entry=ttu

[Bryn666]

In my opinon, this turbo roundabout near the Ashford Designer Outlet gets it right, though it would be preferable if it were signed overhead rather than on the side per what you said. There should also be physical lane segregation to minimise confusion, but I think the chevrons are enough. Before the pandemic, the junction was a standard roundabout. This is one of those cheap but cheerful upgrades which major roundabouts across the country should receive, especially when dual carriageways are involved.

Yes, that looks good, and GMaps shows it as zero congestion. I agree that a conversion to turbo (or, closely related, spiral) of many poorly performing rbts would be in order.

Are there many turbo's in the UK now? I've never encountered one.

Observation: this one's not 'pure-turbo'. With only two circulatory lanes but three 2-lane exits, there remains some in-roundabout lane changing/crossing. That number of exit lanes should require 3-lane approaches and at least three single-lane circulatories. But that wouldn't be 'cheap-and-cheerful', and is unnecessary here. It works.

Digression, with apology: the LILO-GSJ about 600m east looks rather extravagant, in the circumstances!
https://www.google.com/maps/@51.1262864 ... ?entry=ttu

We have 0 turbo roundabouts, none of the three that have been built - in Bedford, Ashford, and this one, meet the Dutch definition.

They are advanced spiral roundabouts, and will improve safety (but not capacity, as there will still be problems posed by poor lane discipline and high circulation speeds), but it is a complete misnomer to call them a turbo roundabout.

[ellandback]

I watched a YouTube video about this last night. It was hard to tell, as he was quite subtle about it, but I got the impression the creator was not a fan of DMRB. Name seemed vaguely familiar ...

[Nathan_A_RF]

In my opinon, this turbo roundabout near the Ashford Designer Outlet gets it right, though it would be preferable if it were signed overhead rather than on the side per what you said. There should also be physical lane segregation to minimise confusion, but I think the chevrons are enough. Before the pandemic, the junction was a standard roundabout. This is one of those cheap but cheerful upgrades which major roundabouts across the country should receive, especially when dual carriageways are involved.

It's not a turbo roundabout, it's a roundabout with some paint. That signage is also horrific and unauthorised. It is the wrong colour, wrongly incorporates a warning sign, tells you to get and stay in lane at the same time, and wastes space & causes confusion by duplicating all the destinations. Not to mention the strange arrows, which could be designed better, and the fact this sign comes before the actual direction sign.

[wallmeerkat]

A77 at Monkton has a right turn arrow

https://www.google.com/maps/@55.5217777 ... ?entry=ttu

albeit probably reinforcing that you need to get into the right hand lane to stay on the A77