Safe Speed Forums

I'm very late to this thread but this is a huge pet-hate of mine.

On my drive home I have two lanes at 70mph, which merges into single carriageway at 60mph. Doesn't take a mathematical genious to figure out that the 60mph road can handle less cars per unit time than the 70mph 2 lane road before it.

Assuming that we have very heavy rush hour traffic, the 70mph road will only dispose of as many vehicles per unit time that the 60mph road can handle (including all it's junctions and thus average speed of approx 20mph*).

Once people accept that the 60mph SC is at the very limit of it's capacity, it's easy to see why the queue length on the DC is largely irrelevant. early merging, whilst wasting one lane, allows total traffic to leave the DC at 20mph*. Driving up two lanes and late merging does not increase the number of vehicles which can leave the DC in any given time, it just means that the queuing drivers must stop to let over-takers join, thus slowing the queue.

I accept that filling both lanes can clear DC junctions earlier, but it will seriously piss off drivers who queue.

The same problem lies behind anger towards drivers who perform 270's at roundabouts and other such manouvers to pass queues.

The reason for any queue is because the exit route is at capacity.

To pass the queue serves only to position one's self ahead of other drivers.

IF zip merging worked AND all drivers kept a safe distance AND other drivers did not abuse this buffer zone THEN zip merging would work and I would fully support the idea. As it stands, and knowing the British public, it hasn't got a snowball's chance in hell of working any time soon.

There's a piece of (joking) driving advice around Aberdeen that I'm sure plenty others will have heard also - "Never leave a safe distance - someone will fill it putting you into an even more dangerous position"

* 20mph is an arbitary speed but is typical of commuter routes round Aberdeenshire where most of my experience lies.

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I encounter 2 zip merges a day (on each side of a stretch of single carriageway) and there are times that leaving a gap for the person in lane 2 doesn't work out great, because you have a tailgater, so then the person behind the first car also pushes in... It's quite annoying and aggrevates the tailgater because you have to slow down to increase your distance... This particular queue can reach about 2 miles, which is by no means long, but it can take the guts for 45 minutes to make your way from the back to the end (and for Northern Ireland it's pretty long)... The problem is probably too much traffic, the single carriageway road is very busy, and it's a bus route with a school near one end, which doesn't help.

I feel fine letting one person in, as the merge in turn sign means... But it's just when you get someone chancing their arm after that and bullying their way in...

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Mike

the best solution for someone "chancing their arm" would be to call their bluff - easier if you have a crappy old car and don't mind the odd dent, perhaps. If their car is dent free and relatively pristine, maybe worth the attempt, if they are in a white van with multicolour patches at bumper level (despite white van men being above all criticism on this site ) maybe better to let them go.

Where does the law stand on this? Or perhaps more importantly, the insurers? Hoping that the other vehicle is insured (on balance, they probably are), I know that rear-enderd are usually blamed on the rear vehicle, is there a standard for side collisions?

Of course, this is all rubbish coming from me as I would probably let the chancers in - I've had my brush with a violent nob on the road, and ones enough thankyou very much!

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COAST Not just somewhere to keep a beach.

A young loner on a crusade to champion the cause of the innocent, the helpless, the powerless, in a world of criminals who operate above the law.

Yea Gods! No, no and thrice no. Becasue 'call their bluff' actually means trusting them not to cause a crash.

The correct approach may be 'bluff and cave' (frequently practiced in big cities). This is where you deliberately create the impression that you are not going to give way, but ultimately you give way meekly and completely before any risk of a crash presents itself. The advantage of 'bluff and cave' is that 9 times out of 10 you can win - it's a question of the quality of your bluff...

But never trust the other guy not to cause a crash. He just might be stupid enough and it simply cannot ever be worth it.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

No it's not, in the case of a typical 2 into 1 or 3 into 2 situation. It's the momentary capacity at the merge point. As you will have noticed, once vehicles have entered the constricted stretch, traffic speed picks up. Merging early is inherently inefficient and stupid.

Until you reach the physical point of lane closure, both lanes are open and available for use, and we should therefore be free to use the road space fully.

Those who choose at an early stage to confine themselves to the lane that remains open beyond the point of the constriction, are delaying themselves of their own free will.

To my mind the best answer to this potential source of conflict is to deploy signs instructing drivers to "use both lanes then merge in turn" or words to that effect.

Although I basically agree with the Observer, I think it is often regarded as pushing in by some drivers, so it is advisable to make your move in a fairly orderly and unhurried manner. This can make the difference between causing an upset and getting away with it reasonably harmoniously.

It ain't what you do, it's the way that you do it?

Best wishes all,
Dave.

Glad you agree.



Ah, but that's where you are wrong.

No, that's where he is right - an 18 year old youth died proving it on the very stretch of road which I used to illustrate my point in this thread (Jan 27th) http://www.safespeed.org.uk/forum/viewtopic.php?p=64412#64412
He either left it too late, or somebody failed to let him in - consequently he struck two vehicles coming the other way, and was killed.
It's a sad way to prove a point, but there you are.

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Time to take responsibility for our actions.. and don't be afraid of speaking out!

Whilst remaining respectful of the fact that someone lost their life in the case Ernest mentions, I don't see that zip-merging on a DC is the same at all as you don't have the on-coming traffic / danger element in the same way.

I think the basic fundamental point about zips is that thre's space between the links when the zip is unfastened, but when they're zipped up they contact each other.

Unless someone can think of a workable system whereby drivers leave 3 times the distance between cars on a DC compared to a SC then L1 will always need to slow down after the merge to allow cars in front to move ahead to restore the distance between cars.

This IS what happens and thats why L1 always ends up crawling IF a few people use L2.

When L2 is blocked (a crash at the merge and a police car in attendance shows this off beautifully) then L1 carries on past the merge at the same speed as the SC following.

Leaving that alone for a moment, what are other people's comments on the roundabout queue jumpers? Or is that a selfish way of making progress too?

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jamie duff for President. There is no need to push in, I've just checked my mirrors and there appears to be loads of space AT THE BACK OF THE QUEUE

It depends on what you mean, if you mean using the right lane to go all the way round to take a left or a straight on then that probably is wrong in most circumstances since you are blocking the exits for traffic that shouldn't have anything to do with your manovore and ulitmately taking one of the spaces from the road that you have come from.

However I have no problems with use the right hand lane of a roundabout to go straight on with only 1 exit lane providing it can be done safely, and preferably with justification, for example it may be the only appropriate opportunity to get past a slower car. I have no problems if I'm the one being overtaken either, providing they don't then pootle on holding me up afterwards!

Jamie,

When I leave my place of work at night there is a roundabout at the bottom of the road, the traffic queue’s back for about a mile sometimes, About 500 yards before the roundabout the road spreads into two lanes to allow for people who want to turn right. Lots of drivers enter the right hand lane indicating to turn right only to use the roundabout as a U turn to turn left. This really gets my goat, the only thing is I sometimes wonder should I do the same thing, and who's the mug? I haven't yet and it is to me selfish to think like this, but that is the (selfish) society we live in.

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Useless laws weaken necessary laws.

Suppose that's true... Any attempt to merge EARLY will effectively extend the limited capacity section and make matters worse.

(Imagine that everyone dutifully joins the L1 queue 1 mile before the single lane section - we now have an extra mile of single lane section...)

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

This does not happen in every case, but as long as there is a chance this might happen, then merging at a SAFE distance from the pinch, with a margin for error would appear to be the best policy.

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Time to take responsibility for our actions.. and don't be afraid of speaking out!

Original post was about zip-merging in dual carriageways. The two situations (Ernest's and on DCs) are vastly different and I don't think it's fair to compare the two. Leaving it late in the case above when two lanes become one with on-coming traffic as the barrier is dangerous and foolish to the extremes. You haven't got the same danger with static signs so the issue becomes more one of "queue jumping" (or not) rather than life and death (which it unfortunately was in the case above).

Glad we all agree on roundabouts then



Without any intention of sarcasm on my part, do you think that spacer chevrons on the road on both lanes could effectively space cars to allow zip merging to work? I'd be willing to give it a fair go

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As I posted earlier. Zip merging has been introduced on the A629 just outside Halifax and it works perfectly well.

This is at the end of a DC. The zip point is well in advance of any danger from opposing traffic.

So the idea that it couldn't work in the UK is clearly nonesense.

Don't know about other areas , but A444 heading north at J3 of M6, has 3 lanes mreging into 2, with sign in great big letters "merge in turn" - get in the outside lane and try - the attitude seems to be "you're q jumping" ---try to merge reasonably on the M6/M1 - same attitude - perhaps it's a southern thing - i don't know , only that the attitude here and south sems to be that it's all about not letting a car in front of you.

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lets bring sanity back to speed limits.
Drivers are like donkeys -they respond best to a carrot, not a stick .Road safety experts are like Asses - best kept covered up ,or sat on

Part of the problem (I think) is that beacause some people merge very early (like 600yds early for roadworks ), drivers who were always in L1 have probably already each let quite a few people in by the time they get to the merge, and consequently think "Well, I've let five people in, why should I let anyone else in?"
I'm in no way blaming early mergers, but they probably use up L1 residents 'generosity ration'.