Safe Speed Forums

I see the end result of the following motorway scenario quite frequently. I do not often drive particularly long distances on motorways but do drive the busiest 10 mile stretch of the M25 twice every day. I'm interested in other views, especially any wagon drivers and resident BiBs.

Imagine a busy but free flowing motorway. A wagon in lane 1 is approaching the 1 mile marker to a junction, say a motorway interchange. He's on the limiter at 56mph. Somewhat timid driver in L2 behind, perhaps unsure of route, sees the 1 mile marker and decides to tuck in behind wagon. A little further back, there are a few cars in lane 2 at 70mph, who are also want that junction. They could go past car 1 and wagon but there's a middle lane resident ahead. So they too reduce speed and tuck in. Soon there's a dozen or so cars in single file behind the wagon and all at 56mph - and all bunched up. The wagon is still 3/4 mile from the junction.

A faster car coming up from behind in lane 2, having passed the 1 mile marker, sees the back of this convoy and thinks "uh-oh - that's a queue for my junction". Not wanting to jump the queue or risk missing his junction, he brakes heavily to join the back of the 'queue'. The heavy braking forces a ripple backwards and now the flow has been interrupted. Following cars in lane 1 are also forced to brake and the resulting drop in lane 1 speed forces wagons further back into lane 2. This of course means that two lanes of 70mph+ traffic are now forced into filtering past the wagon in lane 2 who is now passing lane 1 traffic forced to slow and bunch up because of the convoy further ahead.

Now, to traffic approaching the 1 mile marker from behind, the tail of the convoy really does look like a queue. So, inevitably, more people join it. Some drivers, perhaps with local knowledge, get past the wagons, see the tail off the convoy and decide to cruise on past in lane 2, and then slip into a space nearer the junction. Problem is, all the traffic is bunched up and the gaps to slip into look a bit on the small side. So they slow down, to make it easier to take advantage of a smaller gap. This slows down the traffic behind, that was starting to get back up to speed, having passed the wagons forced into lane 2 and so the lane 2 traffic now bunches up as well.

Now some cars, who were travelling much faster in lane 3, and were slowed to filter past the wagons in lane 2, start to get back up to speed. But wait, some of them want this junction and now they're approaching the half mile marker and the back of the convoy (still headed by the wagon on the limiter, who now has 1/2 mile of empty lane 1 ahead of him). And the gaps in the lane 2 traffic have all closed up so it's hard to get back into lane 2 now, never mind lane 1. A few of the bolder drivers (who also want this junction) actually accelerate, reasoning (correctly) that if they can get ahead of this congestion, there will be gaps further ahead. They sail past the head of the convoy, still 1/4 mile from the junction, congratulating themselves on their perspicacity.

Meanwhile the problems behind the convoy continue to build. Traffic has slowed in lanes 1 and 2 and gaps have closed up. Traffic which is trying to keep moving in lane 3 is passing the slower traffic in lanes 2 and 1 but the ones who want this junction are slowing down, increasingly anxious to find a gap to get into lane 2 and then into lane 1. There are still some bolder drivers who recognise the symptoms and press on in lane 3. Some of them make it comfortably but the later ones are now approaching the 300 yds marker. They have a problem getting into lane 2 and even more of a problem to get into lane 1, because that's full of slower traffic and other traffic which is also looking for gaps in lane 1.

These people become increasingly desperate. There are no gaps anywhere. They can't slow down because of traffic behind. Some maintain speed, hoping to find a gap where the slip road widens to two lanes. Some make it but others find their exit is cut off by slower traffic going straight on in lane 1 or by cars at the head of the convoy pulling out to overtake the lead wagon, now that the slip road has widened to two lanes. The gaps, of course, are still tiny. Meanwhile, at the head of the convoy, the wagon driver with open road stretching ahead of him is thinking "Why the f*** is nobody overtaking me?"

Not surprising, is it, that we have congestion around junctions and instances of cars 'cutting in'.

So what lessons can be learned? I suggest the following.

1. Leave decent gaps, especially around junctions. If another car wants to fill the gap, then let it. It's not slowing you down and may be avoiding congestion behind you.

2. Don't be a sheep. Before you tuck in at the back of a convoy, look ahead and consider whether you could comfortably get ahead of the convoy. It's not queue jumping and it will help to avoid congestion behind.

3. If somebody 'cuts in' to the gap ahead of you, consider whether the cutting in is actually because you didn't leave enough space for a comfortable merge.

4. The 'cutting in' driver, even the one who joins the slip road very late, may be acting selfishly or may have been unfortunately stranded when he was trying to keep things moving. You can't know what's in his mind so give him the benefit of the doubt.

A decent gap between vehicles is vital on motorways. If everyone maintained at least the two second gap and looked for brakelights of cars at least 600 to 800 metres ahead, and reacted accordingly then we would have much less of a flow problem. Likewise if someone moves into your gap, open the gap again as reasonably quickly as you can.

Your advice as ever is spot on Observer, and it exhibits the importance of anticipation and planning in your driving. The best use of these skills can only be with full awareness of what is going on around, both in front and behind. Good regular mirror checks and horizon 'drawback' view for assimilation of hazards will give you the almost immediate awareness of what options you have when approaching a busy junction.

One of the most important points in planning is to look for your gap. If you can see a gap ahead which your speed relative to the other vehicles will allow you to move into then make the most of it. It is NOT selfish, it is making the best use of the motorway space.

You must always however be aware and anticipate the possibility of a junction queue tightening because of the sheer volume of traffic actually at the junction, ie stationary traffic backing back on to or towards the motorway. In these situations, your advanced observations will have advised you that your rightful place is at the back of the queue, (unless your local knowledge says you can progress without 'bullying' into the queue ahead), and you should be able to tuck in with the least of fuss.

It would be nice in these 'potential conflict' situations to have 'courtesy' and 'consideration' as the default attitudes, rather than 'antagonism' and 'aggression' as is often the case. If for the best of reasons and intentions, your efforts to reduce the junction peristalsis fails and you have to move into someone elses two second gap, then the usual courtesy signs should help. The chap behind should be able to see from your subsequent driving behaviour that you're one of the good guys .

_________________
Fixed ideas are like cramp, for instance in the foot, yet the best remedy is to step on them.

Ian

Funny how one always seems to get convoys of nose-to-tail wagons in lane 1 just when one's exit is coming up - however if the other lanes are reasonably clear then one can always speed up a bit and get past the convoy in good time.
It's worse when there are also wagons in lane 2, then there's only one lane left in which to pass - and if someone's sitting in lane 3 at 70mph then you've got little or no chance, except to wish you were still two miles furher back.

Cheers
Peter

True - Ian. If only folks out there realised that early planning is essential on motorways - simply because a lot can happen in a short space of time at high motorway speeds. (In a way this is linked to burnbanks' sorry tale - when according to his story - he misjudged the approaching speed of the faster car when he pulled out to overtake the lorry).

As usual Observer and yourself pass excellent comments and advice. I would simply add that you should aim to look at least mile ahead or as far as the next curve if that is less - and maintain all observation and mirror skills to take in all points in-between - you should never be staring at the bumper bar in front of you (unless in the standard Bank Holiday queue... ) and you should always be looking for the slightest evidence that the slip road could become blocked.

Ideally the two second gap at the very least should be maintained - doubled in bad weather conditions and extended even more if you observe the occurrence of bunching. You should also be aware of acute bends at the end of some of these slip roads as well...

Observer has already mentioned this in the substance of his post - but perhaps it needs spelling for browsers:

Too many do not appreciate how the signs are used on the motorways: this can aid planning techniques. If you are planning to leave the motorway - the first sign for the exit you require is one mile from the exit road and the second one a half mile from the required exit road.

Inevitably some will cut across your path form L2 and L3 on very busys motorways and it is a case of being alert , tolerant and courteous. Was with one of the Swiss this weekend. He was in L2 and not overly familiar with the road. The first marker was obscured from his view by 3 nose to tail HGVs and he noted the second one in a clearing. I was in the passenger seat and he simply looked straight ahead - spied a gap, indicated his intention, maintained a steady speed which matched the road condition he was in, and gave one of those cheeky wide smiles to the person in L1 as he nipped into the space about 500 yards from the slip road - causing very little inconvenience to any other driver. If he had found he was unable to join this slip road - he would have just acknowledged an error and continued to the next exit and doubled back - he does have Sat Nav as well to assist...complete with every speed trap in Europe downloaded into it.. or at least for the countries where his other useful gadget is illegal.

_________________
Take with a chuckle or a grain of salt
Drive without COAST and it's all your own fault!

A SMILE is a curve that sets everything straight (P Diller).

A Smiley Per post
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Approach love and cooking with reckless abandon - but driving with a smile and a COAST calm mind.

Here here (or is it hear hear?). The queue mentality is one of the worst British traits. You see it when joining a congested motorway too. People crossing the chevrons even to get in the queue as soon as possible. USE THE WHOLE SLIPROAD NUMPTIES!



It's not always true.

M62 E J26, markers at at 2/3mile and 1/3mile - catches out a lot of drivers so obviously many are aware of the standard signing.

Worse is M62 W J24. The junction is the type where the left lane becomes the sliproad and is signed at least two miles away. It is also one of the steepest uphil stretches of that motorway (hence the 4 lanes). The result is traffic which should be in L1 moves over far too early (mainly trucks struggling up the hill) making the extra lane near to useless. The road flattens before the junction and traffic spreads out. One can usually find a good gap between the half mile and 300yrd markers but then you have to watch for people who got themselves in L1 two mile back and are now undertaking the slower L2 traffic.

I've noticed others around the country which don't conform to the 1mile/half mile rule. the M60 around manchester is bad for it and Hartshead Moor services is signed at two and a half miles.

Forgot about the dreaded M60 and thos two junctions on the M62. Also the M1 where it joins A14 and the M6/M55 junctions...

Blame the road engineers - though hear the M1 in the Midlands is to become a 4-laner. Hope they get the engineering right this time....

_________________
Take with a chuckle or a grain of salt
Drive without COAST and it's all your own fault!

A SMILE is a curve that sets everything straight (P Diller).

A Smiley Per post
FINES USfor our COAST!

Approach love and cooking with reckless abandon - but driving with a smile and a COAST calm mind.

The word 'queue' is unfortunate when applied to traffic.
In a supermarket, bank or whatever, Each person ahead of you in the queue means an extra wait of several minutes, and so queue-jumpers are (rightly) frowned upon.
The same doesn't (or shouldn't) hold true about traffic. Every driver ahead of you will (or should) extend your journey time by two seconds, if at all.
You do get people who barge in ahead of you, only to hold you up - ut these are thankfully in the minority.
Most so-called 'queue jumpers' are simply trying to make better use of otherwise-wasted roadspace. But they are nonetheless frowned upon - to the extent that even overtaking slow traffic quite safely is likely to elicit howls of indignation (flashing lights, hooting etc)

Cheers
Peter

The truck speed limiters play a large role in this problem. We have to evaluate the safety benefits properly and then decide if we should keep them. There must be enough data around after about a decade.

Taking the perspective of an individual driver, I'll often plan my approach to the exit from L3 in busy conditions. (meaning adjusting speed to find L2 and L1 gaps, not meaning doing the three lane swoop) At least this way I can avoid being part of the problem. On occasion, with a nice gap up ahead, accelerating to acquire the gap and doing the three lane swoop isn't a bad solution.

Of course if all three lanes are chocka then moving to L1 early can be the best strategy. In extremely busy conditions a mile may not be enough to change lane twice if you insist on decent gaps.

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

This isn't necessarily the best thing to do. If someone moves into your gap for a short while, like when they're making for an exit or passing an obstruction, it's probably best not to back off and just drive with extra caution with a reduced gap - unless there's nobody behind you.
If you back off it means that everyone behind also has to back off, in order to maintain their gap, and this is exacerbated if several cars are tring to get into the lane at the same time. The result is too often a complete breakdown in traffic flow. It only takes 14 cars overreacting by slowing down by just 5mph too much, for 70mph traffic to be reduced to a standstill.

Cheers
Peter

Sorry, Peter
The 'reasonably' was meant to imply all those other considerations. Occasionally I try to use one word in place of one hundred, but it sometimes doesn't read quite the way it was intended.

Thanks for the clarification.

_________________
Fixed ideas are like cramp, for instance in the foot, yet the best remedy is to step on them.

Ian

Yep Pete - happens a lot round J1/2/3 on the M6(and usually L3 has a q of sales rep types ) - someone in another post suggested a solution if stuck - "ask a convoy member for help" - i think it was a truck driver who said it - indicate left and wait - more often than not a trucker in the convoy in L1 will respond , create a gap and let you in. Be nice to see the majority rather than the minority of car drivers doing this as well - called courtesy in olde worlde terms.
Mention was made of shorter than normal spacing between junctions - add M6 J10 to list, from memory i believe it is only about 2/3 mile from J9-J10.

Do our resident BiBs (and anyone else) think it is reasonable to use some measured acceleration where safe (and possibly exceed the speed limit) to overtake the "queue"? This seems to be one of those times where you can justifiably accelerate out of potential trouble and inconvience others less.

Sam - that's where we use most discretion!

_________________
Take with a chuckle or a grain of salt
Drive without COAST and it's all your own fault!

A SMILE is a curve that sets everything straight (P Diller).

A Smiley Per post
FINES USfor our COAST!

Approach love and cooking with reckless abandon - but driving with a smile and a COAST calm mind.