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WhiteBlueRed wrote: ↑Fri Feb 03, 2023 09:16
Probably not so botched, given that it is legal to turn across a double white line in the UK. What I don't get is why they continued the double white line across the junction, when right turners are clearly allowed to turn, judging by right arrow. Wouldn't it have been cheaper to have a gap in the line, aswell as more logical? https://www.google.com/maps/@52.74347,- ... 384!8i8192
A gap would have made overtaking legal at that point, which would be a bad idea. It's probably quicker just to keep painting doubek lines than have to change to a default centre dashed line and back a few yards later.
In practical terms it wouldn't as passing the wrong side of a keep left sign is an offence.
The chances of confusion about overtake rules are pretty much zero I'd say. Although I think the double line either side of the chevrons after is a botch.
The chances of confusion about overtake rules are pretty much zero I'd say. Although I think the double line either side of the chevrons after is a botch.
I feel the increased use of double white lines with chevrons is unnecessary. It has led to botches with double double white lines, increases the amount of paint on the road and looks less aesthetically pleasing.
When traffic queues back beyond the turning lane, they lead to the choice of either disregarding the double white lines or impeding flow of straight through traffic.
WhiteBlueRed wrote: ↑Fri Feb 03, 2023 09:16
Probably not so botched, given that it is legal to turn across a double white line in the UK. What I don't get is why they continued the double white line across the junction, when right turners are clearly allowed to turn, judging by right arrow. Wouldn't it have been cheaper to have a gap in the line, aswell as more logical? https://www.google.com/maps/@52.74347,- ... 384!8i8192
A gap would have made overtaking legal at that point, which would be a bad idea. It's probably quicker just to keep painting doubek lines than have to change to a default centre dashed line and back a few yards later.
I seem to recall double white can be crossed to enter another road anyway, but many councils and highways engineers have dashed lines here (not sure what the prescribed variant is).
Actually, that raises a point: in UK law, is it illegal to *cross* the double white line, or to remain on the wrong side of it? The Highway Code says "do not cross or straddle" the line, but it doesn't say anything about remaining on the wrong side to complete an overtake (except for slow vehicles with otherwise excellent visibility). I've always taken the latter as being illegal, and of course quite dangerous, but is it actually specifically illegal?
WhiteBlueRed wrote: ↑Fri Feb 03, 2023 09:16
Probably not so botched, given that it is legal to turn across a double white line in the UK. What I don't get is why they continued the double white line across the junction, when right turners are clearly allowed to turn, judging by right arrow. Wouldn't it have been cheaper to have a gap in the line, aswell as more logical? https://www.google.com/maps/@52.74347,- ... 384!8i8192
A gap would have made overtaking legal at that point, which would be a bad idea. It's probably quicker just to keep painting doubek lines than have to change to a default centre dashed line and back a few yards later.
I seem to recall double white can be crossed to enter another road anyway, but many councils and highways engineers have dashed lines here (not sure what the prescribed variant is).
Actually, that raises a point: in UK law, is it illegal to *cross* the double white line, or to remain on the wrong side of it? The Highway Code says "do not cross or straddle" the line, but it doesn't say anything about remaining on the wrong side to complete an overtake (except for slow vehicles with otherwise excellent visibility). I've always taken the latter as being illegal, and of course quite dangerous, but is it actually specifically illegal?
TSRGD defines the offence as not being to the left of the line. Crossing is not prohibited (even though its in the title of Schedule 9 Part 7 Item 9) which is why its use in tunnels etc between lanes in the same direction has no meaning.
Bomag wrote: ↑Fri Feb 24, 2023 00:51
TSRGD defines the offence as not being to the left of the line. Crossing is not prohibited (even though its in the title of Schedule 9 Part 7 Item 9) which is why its use in tunnels etc between lanes in the same direction has no meaning.
Interesting - thanks. I'd never quite thought about it in the context of road tunnels, that poses even more questions now.
Bomag wrote: ↑Fri Feb 24, 2023 00:51
TSRGD defines the offence as not being to the left of the line. Crossing is not prohibited (even though its in the title of Schedule 9 Part 7 Item 9) which is why its use in tunnels etc between lanes in the same direction has no meaning.
Going back to this, I suppose this means the double whites on the M1's first junction in London are of no meaning. Well, certainly they don't seem to trouble the odd German luxobarge driver.
Bomag wrote: ↑Fri Feb 24, 2023 00:51
TSRGD defines the offence as not being to the left of the line. Crossing is not prohibited (even though its in the title of Schedule 9 Part 7 Item 9) which is why its use in tunnels etc between lanes in the same direction has no meaning.
Going back to this, I suppose this means the double whites on the M1's first junction in London are of no meaning. Well, certainly they don't seem to trouble the odd German luxobarge driver.
Yes, if they wanted to stop traffic moving from lane 2 to 1 and vv the prescribed marking is Diagram 1042 (as used for tiger tails). If you can not fit in Dia 1042 in then there should be no need to restrict lane changing at this point.
It's fairly obvious that the intent is to stop lane changing into the free-flow lane when the roundabout is blocked, or vice versa, which suggests there has been a historic safety issue at this location.
Perhaps the fact the only way to stop unwanted lane changes on motorways at junctions and their approaches is using needlessly spatially wasteful tiger tail markings is another example of a failure within the TSRGD and DMRB. Literally the rest of the planet copes without tiger tails on exits, preferring to just use a solid line or signs. We have come up with an unworkable situation that causes more problems than it solves, as witnessed by the amount of last second lane swoops across the chevrons witnessed at virtually every tiger tail exit in the country.
But hey, us mere mortals without more letters after our names than within them know nothing about traffic behaviour so I'm wasting my time pointing this out.
Bryn Terminally cynical, unimpressed, and nearly Middle Age already. She said life was like a motorway; dull, grey, and long.
This one at the exit from the Dartford Tunnel is possibly unique as it's dashed on one side. The intent is obviously to prevent traffic from the right hand tunnel from weaving across to take the exit but is often ignored (I even once saw a police car cross it).
Interestingly enough the right hand carriageway of the Dartford Tunnel, which was the old southerly route for the A282, has a longer stretch of double whites on the northern side of the river. My guess is that the intent here is that this be useful for contraflow working when the bridge is under maintenance as the contraflow paths merge right as the double whites begin. This must be one of the few sets of road markings that has a different intention when operated in a temporary flow condition? I may be talking out of my a*** here but it looks like an odd thing to do otherwise!
Slip was reopened with short merge and no double whites, congestion increased
(Slip was reopened just before Glasgow hosted COP27 - the slip being a useful route between the conference venue and Edinburgh hotels - surely just a coincidence otherwise COP27 could be accused of increasing congestion for the past 16 months)
Can't quite recall at which stage the extra lane was added after junction 18 but I think the double whites still helped by
Allowing traffic on slip and main line more time to match speed and get into staggered formation
Ensure merging happened on straight rather on bend
Slip was reopened with short merge and no double whites, congestion increased
(Slip was reopened just before Glasgow hosted COP27 - the slip being a useful route between the conference venue and Edinburgh hotels - surely just a coincidence otherwise COP27 could be accused of increasing congestion for the past 16 months)
Can't quite recall at which stage the extra lane was added after junction 18 but I think the double whites still helped by
Allowing traffic on slip and main line more time to match speed and get into staggered formation
Ensure merging happened on straight rather on bend
A set of botched markings trying to fix an ineffective layout. Even with (unlawful) raised ribs there is a considerable amount of overunning. The use of cylinders looks to be consistent with Detail G, H or K from Chapter 8; however, they found the same problems as we get at road works.
It comes down to the basic problem, shown up over 15 years ago, that a full width Dia 1042 tiger tail (2.0m) is both effective and safe. If it is thought that you need double while lines then that solution is between one and two magnitudes less effective (and less safe). Even with something like MMA it is an unacceptable maintenance liability. Perhaps they could have tried some proper lane use signs and ADS. Even better would be to design layout changes to DMRB, even accounting for some of the more questionable IANs we still have the safest motorways, particularly considering the traffic flows. This is because of DMRB, not in spite of DMRB. There are some Druidic naysayers but the forum settings send them to Yns Mons.
tom66 wrote: ↑Mon Feb 27, 2023 17:49
Interestingly enough the right hand carriageway of the Dartford Tunnel, which was the old southerly route for the A282, has a longer stretch of double whites on the northern side of the river. My guess is that the intent here is that this be useful for contraflow working when the bridge is under maintenance as the contraflow paths merge right as the double whites begin. This must be one of the few sets of road markings that has a different intention when operated in a temporary flow condition? I may be talking out of my a*** here but it looks like an odd thing to do otherwise!
Been there done that, I think its now seven times in the last 20 years where the markings on the A282 are the cause of the problems they are asking us to fix. Hindhead tunnel has the authorised hazard marking for use in normal and contraflow layouts.
Bomag wrote: ↑Tue Feb 28, 2023 01:10Hindhead tunnel has the authorised hazard marking for use in normal and contraflow layouts.
I wouldn't hold that up as a paragon of good design - it's extremely ambiguous as to whether it's a dashed line or a solid line, since the breaks are tiny and appear to be only for cats eyes. There is no parallel in the Highway Code so I don't know how drivers are meant to be able to interpret them, and there's a running argument in my family about whether or not changing lanes is permitted.
As a consequence you routinely see people getting frustrated with each other: some motorists will cross the line to overtake and others will play policeman, using horns and flashing lights to try to enforce what they think is a solid line. You also see - about 50% of the time you pass through the tunnel during day time - people going slowly in the right hand lane, who won't move left because they think they're not allowed, followed by a convoy of frustrated motorists. Worse, it's reallynot unusual to see people move left, pass on the left, then move right again to get round them. That would be reckless on the open road but it's a serious hazard in a tunnel. I don't excuse the poor driving but I understand why it happens: the markings are ambiguous. It either needs to be clearly a solid line or clearly dashed so that it communicates a single message to everyone.
Say what you like about double white lines in tunnels, they are at least well understood - and isn't that the point?
Bomag wrote: ↑Tue Feb 28, 2023 01:10Hindhead tunnel has the authorised hazard marking for use in normal and contraflow layouts.
I wouldn't hold that up as a paragon of good design - it's extremely ambiguous as to whether it's a dashed line or a solid line, since the breaks are tiny and appear to be only for cats eyes. There is no parallel in the Highway Code so I don't know how drivers are meant to be able to interpret them, and there's a running argument in my family about whether or not changing lanes is permitted.
As a consequence you routinely see people getting frustrated with each other: some motorists will cross the line to overtake and others will play policeman, using horns and flashing lights to try to enforce what they think is a solid line. You also see - about 50% of the time you pass through the tunnel during day time - people going slowly in the right hand lane, who won't move left because they think they're not allowed, followed by a convoy of frustrated motorists. Worse, it's reallynot unusual to see people move left, pass on the left, then move right again to get round them. That would be reckless on the open road but it's a serious hazard in a tunnel. I don't excuse the poor driving but I understand why it happens: the markings are ambiguous. It either needs to be clearly a solid line or clearly dashed so that it communicates a single message to everyone.
Say what you like about double white lines in tunnels, they are at least well understood - and isn't that the point?
The rest of the world manages to use double and single solid white lines in tunnels and everyone gets what they mean; as ever we see the "innovation squad" here in the UK re-invent a wheel that doesn't need re-inventing for what purpose exactly?
Well, I can tell you, job preservation. If you follow internationally recognised practice there's no need for innovators and their money-go-round consultancy cartels dry up. And That's Terrible.
If tiger-tail diverges (whereas tiger-tail merges are good) are so great, why does no-one else rush to have them? If the Hindhead marking is so great, why does no-one else rush to have it?
Bryn Terminally cynical, unimpressed, and nearly Middle Age already. She said life was like a motorway; dull, grey, and long.
jnty wrote: ↑Tue Feb 28, 2023 21:55
I wonder how by motorists actually have any idea about the general concept of "more line = more hazard"?
It's certainly not really part of my driving toolbox, so to speak.
They don't, not least because most "designers" default to just using long lengths of 1004.1/1004 everywhere, including on motorways where it really isn't warranted either. What we have is a classic example of "We Are The Experts, Therefore You Are Always Wrong" coming up with things and not actually bothering to confirm if it aligns with anyone's real world experience. It's this sort of thing that fuels the likes of Michael Gove.
Bryn Terminally cynical, unimpressed, and nearly Middle Age already. She said life was like a motorway; dull, grey, and long.
Bomag wrote: ↑Tue Feb 28, 2023 01:10Hindhead tunnel has the authorised hazard marking for use in normal and contraflow layouts.
I wouldn't hold that up as a paragon of good design - it's extremely ambiguous as to whether it's a dashed line or a solid line, since the breaks are tiny and appear to be only for cats eyes. There is no parallel in the Highway Code so I don't know how drivers are meant to be able to interpret them, and there's a running argument in my family about whether or not changing lanes is permitted.
As a consequence you routinely see people getting frustrated with each other: some motorists will cross the line to overtake and others will play policeman, using horns and flashing lights to try to enforce what they think is a solid line. You also see - about 50% of the time you pass through the tunnel during day time - people going slowly in the right hand lane, who won't move left because they think they're not allowed, followed by a convoy of frustrated motorists. Worse, it's reallynot unusual to see people move left, pass on the left, then move right again to get round them. That would be reckless on the open road but it's a serious hazard in a tunnel. I don't excuse the poor driving but I understand why it happens: the markings are ambiguous. It either needs to be clearly a solid line or clearly dashed so that it communicates a single message to everyone.
Say what you like about double white lines in tunnels, they are at least well understood - and isn't that the point?
If the DWL were properly understood then all vehicles would be in the left hand lane. The warning line in Hindhead works as intended in both normal and contraflow conditions. In normal conditions the standard keep left unless overtaking applies. I don't think Hindhead uses cats eyes, I think we did a statutory Type Approval for Philips studs.
