Chris Boyle ([info]shortcipher) wrote,
@ 2008-01-24 00:54:00
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Current mood: irritated
Current music:Keane - Can't Stop Now
Entry tags:driving, geek, lazyweb, rant

A naive question about lorries
Prompted by my driving to Coventry and back today (I haven't done that for a while). I've never quite understood this one; someone explain it to me please? ([info]gerald_duck, I'm looking mainly at you here.)

How, on $DEITY's green earth, have we ended up in the situation where all HGVs appear to be limited to very slightly different speeds around 60mph and it is legal (AFAIK) for them to attempt to overtake each other on two-lane roads such as the A14, painfully slowly, over the course of about a mile, jamming up dozens of following vehicles? The total time lost to occupants of following vehicles due to this phenomenon seems large. More importantly, so does the increase in accident risks, considering typical impatiently short following distances.

Have there ever been any attempts to get a law passed banning overtaking with a speed difference of less than ~4mph (at least, when there are only two lanes)? If so, what was the outcome?


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[info]captain_aj
2008-01-24 01:37 am UTC (link)
I don't think it's the lack of a law, I think it's lack of enforcement. As far as I know, it's already some sort of offence to unnecessarily impede overtaking. I think this might apply here, but I might be wrong - unnecessarily can be a very vague word.

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[info]linamishima
2008-01-24 02:16 am UTC (link)
I'm also fairly certain there are rules about such things. large and long vehicle overtaking with limited lanes is ringing some small bells....

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[info]lostdreamer666
2008-01-24 08:22 am UTC (link)
HGVs ain't allowed in the outside lane of a motorway if that is what you are thinking...

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[info]crazyscot
2008-01-24 09:03 am UTC (link)
They are not allowed in the outside lane of a three-lane motorway, nor in lanes 3 or 4 of a four-laner.

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[info]pizza.maircrosoft.com
2008-01-24 02:20 am UTC (link)
Have there ever been any attempts to get a law passed banning overtaking with a speed difference of less than ~4mph

i reckon that would be better as a percentage. joggers should be able to overtake pedestrians, for example...

... not that that is really a concern on the A14.

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[info]deborah_c
2008-01-24 11:36 am UTC (link)
about a mile

I think you have the wrong order of magnitude there. I spent just short of ten minutes sitting grumbling behind a car transporter on the M11 on Sunday, as it very very slowly overtook two consecutive lorries.

This is actually not uncommon; worse is when, as the overtaker gets past, the back one of the queue that it's just overtaken pulls out...

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[info]shortcipher
2008-01-24 11:37 am UTC (link)
Funny, I originally wrote "a few miles", then thought I'd exaggerated and edited it.

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[info]atreic
2008-01-24 12:13 pm UTC (link)
If you drove to Coventry, surely you will have noticed that the Highways Agency is trialling just that idea?

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[info]shortcipher
2008-01-24 12:37 pm UTC (link)
I did, but as Clive says, it's just a short uphill stretch in each direction, so although I used it once during the relevant hours (Westbound), I didn't get much information. Also, I don't think doing it on just the uphill stretches will help much (they still spend ages overtaking on the flat trying to exploit minuscule differences in speed limiting), nor do I think a blanket ban on them overtaking on two lane roads is sensible (as Clive says, the lorries will drive too close together).

The law I'd like to see is something like: vehicles whose speed is artificially limited in this way may only overtake when the overtakees are travelling at least 7% below said limit. Or possibly just a time limit on overtaking: you must pull back after 30 seconds. The idea being, a passenger in a car stuck behind can take cameraphone snaps/video of this pointless overtaking lasting 10 minutes or so, and it's fairly simple for the police to look at this and put points on the overtaker's license. There's enough frustration and there are enough cameraphones around now for passengers to bother doing this, and there would be enough fear of this to deter the pointless overtaking.

Edited at 2008-01-24 12:55 pm UTC

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[info]gerald_duck
2008-01-24 12:20 pm UTC (link)
The real solution, of course, is a few more lanes.

I'm assuming that what set you thinking was the "average speed trial" up the far end of the A14, where they ban lorries overtaking on the uphill sections during the daytime. Sadly, I never drive that section of the A14 in the relevant hours, so can't judge how well it works.

In Germany, they often have two-lane Autobahnen where lorries are prohibited from overtaking, then quite frequent crawler lanes up hills. On the uphill stretches they have minimum speed limits on lanes 2 and 3 (from memory, 80km/h on lane 2 and 100km/h on lane 3). This strikes me as entirely sensible.

People keep demanding that lorries be prohibited from overtaking on the Cambridge-Huntingdon stretch of A14; the stock answer is that this would alter the distribution of traffic so as to make it impossible for traffic to merge at junctions, though personally I doubt that.

Yes, I suspect slow overtaking manoeuvres do increase accident risks. Unfortunately, if prohibited from overtaking, lorries would probably end up following one another dangerously close, anyway.

In Spain, there is — or, at least, used to be — a law that the speed limit on single-carriageway roads is 20km/h higher for people who are overtaking. That at least encourages people to get it over with quickly, if not mandating it, but doesn't apply to dual carriageways. The Highway Code also indicates — or, at least, used to indicate — people shouldn't accelerate while being overtaken and should leave room for overtaking vehicles to pull back in, though this isn't mandatory.

Personally, I would like to combine a variant of that Spanish law that also applied on dual carriageways with a law that no vehicle may ever overtake unless it is capable of reaching the overtaking speed limit on that road (note that the capability rule doesn't imply it actually needs to reach it).

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[info]shortcipher
2008-01-24 12:46 pm UTC (link)
The problem I see with a higher speed limit when overtaking is that on a dual carriageway, it can be somewhat ill-defined what time period counts as overtaking. If you pass two vehicles, how far apart must they be for it to count as two overtakes and for you to presumably need to slow down in the middle? Would this be defined; would there then also be a requirement to pull in? Would the limit variation be lane-based? If it's not lane-based, it seems too vague to ever enforce the lower limit successfully on a moderately busy road.

Edited at 2008-01-24 12:47 pm UTC

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[info]gerald_duck
2008-01-24 01:13 pm UTC (link)
If the speed limit became progressively higher in lanes to the right and it was illegal rather than merely deprecated to use those lanes other than when overtaking then the distinction would evaporate. I guess safe stopping distances would need to be the guide to what constituted lane hogging rather than overtaking. That would give people the margin between the two-second rule and safe stopping distance (205 feet and 315 feet respectively at 70mph) in which to move back legally and safely.

Maybe they could double the speed limit while they were at it. (-8

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