Thursday, 23 September 2010

On why lorry drivers overtake each other on dual-carriageways.

One of the most common things I am asked when I tell people I am a lorry driver is 'why do lorry drivers insist on overtaking each other on dual-carriageways when they are doing roughly the same speed, thus blocking the road for car drivers for ages?' So here's the answer: Well, if you are only a car driver you probably won't accept any of this as a justifiable answer but at least you'll have a bit more of an idea why.

These are the factors:

The speed limiter - laden goods vehicles (LGVs) over 7.5 tonnes, and some under this weight, are limited to 56mph. There is a mechanism in the engine which means that when you try and accelerate past this speed, nothing happens, the acceleration just stops. So, what is the point of trying to overtake each other then? Good question, but the fact is they are not all set in exactly the same place. Some don't go much beyond 54 some you can get up to 56.5. The supermarkets are often limited to 53 as this is supposedly optimum fuel consumption speed. If you take the A34 connecting the major transport hub of Southampton to the Midlands, many lorries are travelling the full length of it. It is 110 miles from Southampton to Northampton, a distance that would be travelled almost exclusively on dual-carriageways. A difference of 2 miles an hour would make a difference of 4 minutes on the overall journey. This may not seem like much but it brings me onto the next point -

Time pressures - lorry drivers are under pressure for time both from their transport offices and from the tachograph regulations. Most long-distance lorries are satellite tracked so their transport office knows what speed they are doing and if they are not doing the speed they could be doing, the office will want to know why. Routes are worked out according to how long it ought to take and if you are not sticking to time, connecting routes will be thrown out of schedule (this is especially the case for things like Royal Mail, DHL etc.). Routes are also worked out to make sure that your tacho breaks fall at convenient times for the deliveries. You can drive for 4.5 hours before you have to take a 45 minute break. Last week 5 minutes was the difference between me making it home on time at and me being stuck in the Midlands for 45 minutes, thus making all the post I was carrying late.

The other factors that influence my choice of whether or not to overtake and block the road for ages are:

Load differences and hills - a vehicle that is heavily laden is not going to make it up the hills as fast as one that isn't. However, while some vehicles have a feature where the exhaust brake kicks in automatically to make sure you stay at the speed the limiter is set to, many do not. This means that a vehicle that is heavily laden will actually go faster down the hills that one that isn't. Frighteningly fast in fact! (69 is the fastest I have ever got a laden lorry to go, I tried to break the speed limit for cars but I didn't quite get there. It was fun but scary and I certainly won't be doing it again!). When deciding to overtake you have to make the decision about whether overall you are going faster than the one in front or not. The A34 is hilly, so if you are overtaking downhill (or uphill, depending on which one of you is laden) you also have to decide whether you are going to make it past the lorry in front before the gradient changes again. Personally if I'm being overtaken uphill and the lorry overtaking hasn't managed to get back in by the time we are going downhill again and going the same speed, I tend to brake to let them in to get the road moving smoothly, as long as I accept that overall they are going faster than me. If I don't think they are, and think they were just being aggressive, I won't slow down because I know that sooner or later I will probably have to overtake them again. This may well end up as a scrap that blocks the road for ages.

The final factor is cruise control. Let's take the A31 coming out of Bournemouth towards Southampton through the New Forest. It has some very long steep hills and at certain times, is very busy. If you are driving a lorry up a hill on cruise control and suddenly realise there is a slow-moving vehicle ahead and brake, thereby taking the cruise control off, your speed could drop by 20mph in an instant, which is dangerous, and it can take miles on the A31 to get that speed back. If you pull out straight away and get past it, it takes seconds and everyone is happy. This is a very thinly veiled way of saying 'Oy! Car drivers! Let us pull out!'.

So anyway, these are the reasons why. Having said all that, the speed limit on dual-carriageways for LGVs over 7.5 tonnes is actually only 50 mph but I have heard from a retired policeman that there is an unwritten agreement between the police and the LGV industry that truckers won't be prosecuted for driving at the limiter on dual-carriageways. I certainly know of truckers who have been stopped doing 56 and the police have not batted an eyelid about the speed and I have never known anyone be prosecuted for it but you never know.


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  2. Great post Jenny. Makes sense written down in a coherent fashion (still bloody annoying though!!). I'll probAbly tone my swearing down a bit next I get stuck behind duelling lorries.

  3. The A34 I know it well and spend a lot of time behind the rolling road block of lorry drivers. I see your point about the extra mile an hour shaving a couple of minutes off your journey, but the flipside being the reduction of my speed by 20 mph adds a lot more to mine. Surely the trucking companies should base their calculations on the 50mph speed limit for dual carriageways and anything over that speed should be a bonus.
    As for satellite tracing, if questioned as to why you were doing 50mph instead of 56, the speed limit should be an acceptable answer, otherwise they are insisting you break the law.
    I know my views are purely selfish but if the outside lane wasn't blocked by the duelling Lorries I could probably do my commute in 3 hours rather than the 4 it usually takes me.

  4. That is interesting - I always thought it was some kind of "we own the road" posturing :-))

  5. Fil - to be fair, it is possible to do the Royal Mail routes at 50mph but they are worked out on best case scenario which is almost impossible to achieve during the day so it is an opportunity to make up some time. Added to that, this problem arises on 2 lane stretches of motorway too where the speed limit is 60 for trucks.

    I like the notion of duelling lorries and accept that in some cases there is an element of competition between truckers although I would say this is a very small minority of the overtaking manoeuvres.

    The fact is, for the vast majority of truckers pissing off car drivers is not the primary motivation for their actions. As I write, a Twitter friend of mine is on hour 15 of a 12 hour shift - this is not uncommon. Most of them just want to get to where they are going as fast as they can so that they can go home in time to have some sleep before getting up again.

  6. Pretty comprehensive, well put.

    I've got a slightly different experience, as my employers have chosen to base their run times on a 50mph maximum speed on all M-ways and dual carriageways, so very rarely have need to overtake anyone. This may be specific to my depot, as I've not really questioned other depots drivers about it. Why they've chosen to do this, I believe (but never had it officially confirmed), is to more easily accomodate hold ups & temporary restrictions alongside the problems they appear to be incapable of eliminating at the depot end. This may well have something to do with generally moving staff from standard warehouse duties to the transport and planning departments, instead of recruiting experienced transport staff from outside, and certainly points to a reason for some of the stranger decisions made by the department.

  7. Lorry drivers are not doing it for charity. It's ok on multi carriageways but should be banned on dual carriageways because it is simply driving without consideration under the RTA. The limiters and all that I am against but they do not excuse breaking the law never the less. What makes it worse is that they always pull out into my 'safety gap' to do it too. Often simultaneously pulling out and signalling at the same time. I then have to drop even further back to maintain the gap.

    We are not interested in your problems Jenny. All drivers have a problem and we cannot make driving allowances for them. Bad driving is bad driving.

  8. Keith - I have made no mention of overtaking into the path of oncoming vehicles. I am only talking about overtaking on 2 lane roads at all. It takes a lorry a long time to overtake and frequently I may pull out into perfectly big enough gap and a car comes up behind me and has to wait until I've finished the manoeuvre. That's the way it is. Everyone's journey would be considerably faster if it weren't for all the other vehicles on the road.

    And as you may or may not be aware, I'm a driving instructor, fleet driver trainer and truck driving instructor so I am well aware of safe driving distances. The point of the post was merely to explain to drivers who have never driven lorries the factors which influence lorry drivers' decisions on whether or not to overtake.

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  12. With the technology we have available today, perhaps a variable limiter could be developed? The sat-nav in my car is aware of the area speed limits and is very accurate. So when lorries get to dual carriageways or motorways the limiter makes an adjustment to 60 mph?
    In all honesty, I would like to see freight back on the tracks, utilising the motorway system we have, freight trains in the centre between carriage ways.
    Lorries breaking down and being involved in accidents are too common.... causing absolute chaos.

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  14. I agree with Unknown (29 Jan)

    Freight needs to be back on the fantastic rail infrastructure we once had. There are already a ridiculous amount of car drivers on the road (I often wonder how a large majority of them passed their tests) Lorries have a huge impact on an already weak infrastructure. There are good and bad drivers in all vehicle types it's just that bad drivers in lorries are highlighted significantly more as a result of the impact they have and the size of the vehicles.

    The temptation to pull in-front and slam on the breaks is hard to resist but I have manged it so far. (I am referring to the ones who simultaneously pull out and signal at the same time whilst i am just meters from passing them)

  15. So basically you inconvenience other people for your own convenience (so you can get home on time). Cheers for that.