Merge in turn signs - special authorisation required?

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Bryn666
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Re: Merge in turn signs - special authorisation required?

Post by Bryn666 »

Conekicker wrote: Mon May 30, 2022 21:06 It might be, if one were to squint hard enough, that the permitted variants of Diagram 818.4 (S12-28-22) are enough for a sign stating "Merge in turn" to be permitted. Possible relevant text in larger text picked out below:

1. The legend above the “weight limit” symbol, indicating the nature and location of the prohibition, restriction or requirement, may be varied as appropriate;
2. The “weight limit” numeral may be varied;
3. The “weight limit” symbol may be varied to a symbol shown in column 3 of the sign table in Part 20 at items 25, 27, 33, 34 or 35 or omitted;
4. A distance to the location of the prohibition, restriction or requirement may be shown in accordance with Part 3 of Schedule 18;
5. An arrow pointing horizontally to the left or to the right may be added (and where an arrow pointing to the right is added, the lorry symbol is reversed);
6. “ahead” may be added after any distance where an arrow has not been added;
7. The legend below the “weight limit” symbol, indicating an alternative route, may be omitted or varied in accordance with column 3 of the sign table in Part 3 at item 8 and may include the words “Alternative route via”

Although it could well be that I'm stretching things "a little" (cough) there. One for someone to ask DfT about I think, if anyone is that concerned.
Note that 818.4 includes what was the old 818.2 from TSRGD 2002, where legends such as "No right turn at High St" were permitted. So perhaps "Merge in turn" is OK. Perhaps...

Having said all that, why a Diagram 872.1 (S11-2-15) isn't used would be worth asking of whoever is designing the scheme, given it's an appropriate sign.
The ones in Blackburn are using 872.1 with "merge in turn" in a separate blue panel in case they ever got told to cover them up. If only they still had someone competent enough to push envelopes to their limit there...
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Klepsydra
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Re: Merge in turn signs - special authorisation required?

Post by Klepsydra »

Bomag wrote: Sat May 28, 2022 22:26 Merge in turn signs are not prescribed and while can be used at works under TSRGD Schedule 13 Part 9 has no legal meaning - see D6.23 in Chapter 8 Part 1:2009. As the A2500 in non-primary the signs shown (Diagram 872.1 Schedule 11-2-15) needs to black on white Sch 11-5-27.

Merge in turn signing should never be needed for a permanent layout, if offside traffic cannot merge into nearside traffic then the layout is neither safe nor effective. In this case the issue is likely to be insufficient merge length and/or insufficient downstream capacity - merge in turn will not make the capacity increase. The ADS signing on the A2500 from the A249 is wrong and should be corrected, lane designation sign chould put A2500 traffic in lane 1 and B3221 in lane 2. The merge lane on the A2500 EB exit can be removed.
I assume that (as so often) the Blackwall Tunnel is a special case then?

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Bomag
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Re: Merge in turn signs - special authorisation required?

Post by Bomag »

Klepsydra wrote: Tue May 31, 2022 14:43
Bomag wrote: Sat May 28, 2022 22:26 Merge in turn signs are not prescribed and while can be used at works under TSRGD Schedule 13 Part 9 has no legal meaning - see D6.23 in Chapter 8 Part 1:2009. As the A2500 in non-primary the signs shown (Diagram 872.1 Schedule 11-2-15) needs to black on white Sch 11-5-27.

Merge in turn signing should never be needed for a permanent layout, if offside traffic cannot merge into nearside traffic then the layout is neither safe nor effective. In this case the issue is likely to be insufficient merge length and/or insufficient downstream capacity - merge in turn will not make the capacity increase. The ADS signing on the A2500 from the A249 is wrong and should be corrected, lane designation sign chould put A2500 traffic in lane 1 and B3221 in lane 2. The merge lane on the A2500 EB exit can be removed.
I assume that (as so often) the Blackwall Tunnel is a special case then?

https://www.google.com/maps/@51.4961788 ... 384!8i8192
No, it's because the tunnel operator (at least since 1999) has no competency in traffic signs. The unlawful double white lines being a issue, the operator said the markings stop people crossing, it while the TSRGD actually prohibits being on the offside in the direction of traffic.

A M-I-T sign on a three lane carriageway is a bit amusing. What is traffic in lane 3 supposed to do given that the instruction applies to them as much as it does for traffic in lanes 1 and 2?
welly_j
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Re: Merge in turn signs - special authorisation required?

Post by welly_j »

Bryn666 wrote: Mon May 30, 2022 17:01 Isn't a lot of this problem caused by signal modellers ploughing their lovely maximum saturation flow through a junction straight into a bottleneck immediately beyond. Why does no-one ever seem to raise this as an issue?

This one causes no end of fun at rush hour: https://goo.gl/maps/QhK1BqMAmoJQHfjn8
That stretch from there to the M60 junction deserves to be smart motorway (would be low cost). The hard shoulder could be used as a lane; rush hour speeds are already low, but would be controlled. The M602/M60/M62 junction from this angle needs to be remodelled though - too heavily weighted in traffic joining the M62 at the moment.
cb a1
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Re: Merge in turn signs - special authorisation required?

Post by cb a1 »

Bryn666 wrote: Mon May 30, 2022 17:01Isn't a lot of this problem caused by signal modellers ploughing their lovely maximum saturation flow through a junction straight into a bottleneck immediately beyond. Why does no-one ever seem to raise this as an issue?
Many people who use signal modelling software aren't modellers but software users.

There is a massive demand for competent modellers. The software is generally very usable and very configurable because those who can model need flexibility. However, this doesn't stop those who don't understand what they're doing from testing something that won't work in practice. Also, this type of modelling is often given to very junior staff.

Whilst there are things that the modelling community can do, at the end of the day we need whoever is signing off on the overall design to have the competence to be able to do that competently.
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Re: Merge in turn signs - special authorisation required?

Post by WHBM »

Bomag wrote: Wed Jun 01, 2022 13:56 No, it's because the tunnel operator (at least since 1999) has no competency in traffic signs. The unlawful double white lines being a issue, the operator said the markings stop people crossing, it while the TSRGD actually prohibits being on the offside in the direction of traffic.

A M-I-T sign on a three lane carriageway is a bit amusing. What is traffic in lane 3 supposed to do given that the instruction applies to them as much as it does for traffic in lanes 1 and 2?
The tunnel double white line markings are a TfL policy in all tunnels. They are spreading elsewhere. National Highways uses them on the A282, north of the Dartford Tunnel.

https://www.google.com/maps/@51.4780852 ... 384!8i8192

Regarding the Merge sign on a 3-lane carriageway, it is surely intuitive from the sign, and works well as intended.
pjr10th
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Re: Merge in turn signs - special authorisation required?

Post by pjr10th »

Kevin Roads wrote: Sun May 29, 2022 09:28
Bomag wrote: Sat May 28, 2022 22:26 In this case the issue is likely to be insufficient merge length and/or insufficient downstream capacity - merge in turn will not make the capacity increase.
From Darren's post the issue is the standard British driver's lack of understanding of merging i.e. to leave spaces between vehicles in the joining lane and for merging traffic to match speed and position to slot into those spaces, coupled with the view that anybody who sensibly decides to use the full length of road available (the meging lane) is 'pushing in' or queue-jumping. All this adds up to the classic situation described here with all vehicles stopped at the start of the two lanes and blocking the roundabout.

There's a similar situation here https://maps.app.goo.gl/Pu39pWnXZdSCfkP19 that I occasionally encounter but try and avoid whenever possible. I think the GSV shows it under construction as there are permanent merge signs now (I didn't realise that these shouldn't be used, Bomag) but it isn't really a merge, it's a lane-change which is only needed if the destination requires it.
Needless to say, all vehicles stop immediately after the traffic lights if they want to change lane which causes the usual tailbacks. A solid white line has been painted between the lanes for a short length to try and encourage drivers to change lane further along but this obviously is ignored. I've driven through the lights and remained in the same lane as I didn't need to change and had the expected horn-blasting, shaken fist etc because I didn't stop and 'let them in'.
Jersey replaced many of these 'continue in lane' (of which there are comparatively quite a few on the island) with 'filter in turns' (give way signs with that text on it, giving the meaning merge in turn).
https://maps.app.goo.gl/uPmkFN2UirHxukVg8
https://maps.app.goo.gl/9nDicF4D5f9fWmCs9


I imagine it was down to people having good visibility of oncoming traffic and sitting at the point where the lanes merge rather than continuing through and trying to weave at speed. It also means at the remaining proper merge points (all lane gains) people tend to wait at the start of the merge for a gap if changing lanes and merge in turn is normally applied if there is enough traffic.
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Re: Merge in turn signs - special authorisation required?

Post by wallmeerkat »

In Belfast - when a 2+bus lane turns into a 2 lane

https://www.google.com/maps/@54.5956864 ... 384!8i8192

Nearby merge sign in white - https://www.google.com/maps/@54.5957083 ... 384!8i8192

Elsewhere 2 lanes just become 1 and it's up to traffic to self regulate https://www.google.com/maps/@54.5865178 ... 384!8i8192
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