From: Cynic on 21 Dec 2009 12:39
On 21 Dec 2009 15:44:56 GMT, Adrian <toomany2cvs(a)gmail.com> wrote:
>> The benefit is that it mitigates some human error.
>Not quite. It attempts to workaround one symptom of it.
We cannot prevent humans from making errors. We can only make some
errors less likely to occur, and/or make the consequences of the error
>> Human error happens,
>Yes, it does. But this is the kind of "human error" that really
>_shouldn't_ happen if there is the slightest bit of attention being paid
>to the task in hand.
No error, by definition *should* happen, so you are stating the
obvious. You cannot guarantee that a driver will not be distracted by
something or other and fail to see something that he should be paying
attention to. You can however make it less likely that he will fail
to notice something important, by making the warning or notification
more prominent and attention-grabbing.
>> whether the cost of mitigating it is in all circumstances worthwhile, I
>> don't know.
>Something must be done.
>This is something.
>Therefore, this must be done.
Nonsense. That saying is used when the measure being proposed is
unlikely to have any effect on the thing it is attempting to prevent.
In this case the warning is almost certain to greatly reduce the
frequency of the human error in question. The only question is
whether the number of accidents that occur because of the error, and
would thus be prevented by the measure are sufficient to justify the
From: Cynic on 21 Dec 2009 12:44
On Mon, 21 Dec 2009 13:30:48 -0000, "Doctor Watson"
>>> It could be that height detection systems and warning lights should be
>>> placed on the approaches to bridges less than some specified height.
>>> I've seen such systems in use in some places.
>> There is a very simple system in use at most multi-story car parks I
>> have visited. A board hanging from chains above the entrance. If
>> your vehicle hits the board, it's too high. Adding a switch to the
>> board that will sound an alarm or lights if the board is struck would
>> be trivial.
>> I see no reason why a gantry could not be erected either side of every
>> low bridge - it would cost little more than a road sign.
>Better still why not be aware of where their lorries are going and how
>tall they are?
*Who* should be aware? Obviously the drivers should be aware of both
those things, but clearly that is insufficient to prevent the
occasional human mistake.
If the sat-nav were programmed with the height of the vehicle and the
clearance of all bridges, it would probably go a long way to
preventing such incidents by acting as a back-up to the driver's
awareness of the situation.
But I suspect that equipping all busses with suitably programmed
sat-nav warning systems would be more expensive than erecting the
road warning system proposed.
From: Cynic on 21 Dec 2009 12:47
On Mon, 21 Dec 2009 15:32:51 +0000, Denis McMahon
>I think the systems used on highways tend to be an optical beam across
>the carriageway on poles, possibly so there's no risk of it being hit
>and falling across the carriageway.
A better, but more expensive system.
>Any sort of hanging barrier system would have to be tested to ensure
>that, in this case, it wouldn't have smashed the windows at the front of
>the top deck.
Good point. I think busses are fairly standard heights, so I should
think the hanging barrier could be shaped so as to make it safe for a
bus to hit.
From: Conor on 21 Dec 2009 13:18
In article <d1dvi5d1cl3l249i5gc4c9rb1m01p4aq45(a)4ax.com>, Cynic says...
> >I think the systems used on highways tend to be an optical beam across
> >the carriageway on poles, possibly so there's no risk of it being hit
> >and falling across the carriageway.
> A better, but more expensive system.
Not really. The one on the road from Shrewsbury to Minsterley(A422??)
just off the A5 spends more time broken than working. The southbound one
seems quite good but the northbound one has hardly ever worked.
What does work is a bar with chains dangling down. Can't fail to miss
that and it works in the absence of power.
I'm not prejudiced. I hate everybody equally.
From: Cynic on 21 Dec 2009 14:10
On Mon, 21 Dec 2009 17:09:06 GMT, James Martin(a)hgvu.com wrote:
>>The trouble is that there are idiots who just blindly follow the
>>directions, however stupid they are.
>In that case why if they cannot be totally relied on why waste money
>on one ? .
For the same reason that you have spent money on a computer, and
probably a mobile phone despite the fact that they do not work
reliably all the time.