Hi Folks,
I always find it useful to do a bit of arithmetic in order
to convert statistical figures to a more imaginable scale.
For example, the daily amount of urine secreted in
Manchester -- of the order 1,000,000 x 1.5 litres, i.e.
(11.5 m)cubed -- is enough to fill a volume about equal
to the combined volume of your house and your neighbour's
(or your house alone, if large).
That's something I can grasp, while "1.5 million litres"
somewhat escapes me. Brings it home, as it were.
Today's Guardian carries an article on road congestion [1]
which states that
"On these islands there are 24m cars and 28m motorists.
That's 10 times as many cars as there were in the 1950s;
enough to jam a 12-lane motorway, nose to tail, from
Birmingham to Beijing."
Hmmm. Say 5 yards per car on average, so
5 x 24,000,000 / 1760 = 68,182 miles
which on a 12-lane motorway implies 68182/12 = 5,682 miles.
About right: from my Pocket World Atlas,
Birmingham-Beijing appr. 115 deg Long at appr. 45 deg Lat
= 2 x pi x 4000 x (115/360) x cos(45) = 5677 miles
(this close agreement is a coincidence, by the way: the
"5 yards", "115 deg" and "45 deg" were chosen before the
calculations were done!).
However, while it sounds impressive, a 12-lane traffic jam
from Birmingham to Beijing is somewhat outside my experience,
so I find it difficult to relate the concept to implications
for UK roads.
Hence my question, which is the reason for the above preamble:
Can one find out the road mileages in the UK, counting multiple
lanes (e.g. 1 mile of 6-lane motorway, 3 lanes in each direction,
counts as 6 miles of road)? Preferably broken down by type,
No of lanes, region, etc?
According to data I did manage to find on the DfT website [2],
there is a total length (UK or GB? can't make out) of all
types of road of 392,321 km or about 245,000 miles: enough
to get from Birmingham to Beijing 40 times over.
However, I can't make out either whether this counts simply
the length of road "as a single line on the map" or whether
it counts driveable length (i.e. once for each lane in each
direction). I suspect simply "line on map".
On the reasonable assumption that on average there are at
least two lanes (one each way), then our road network is
equivalent to Birmingham to Beijing at least 80 times over.
More likely at least 100, or more.
This somewhat pulls back into perspective the high-impact
journalistic statement in the Guardian. Converting back
from the "12-lane motorway from B to B'", this suggests
that if our entire car population were evenly spread over
our road network, there would be at least (100/12 = 8) x 5
= 40+ yards per vehicle, at which density they might just
manage to keep moving!
Of course the real problem arises from local congestion
at particular times of day due to people all converging
on the same area, which involves a much more sophisticated
inspection of data. But calculations like the above are
useful in getting things into proportion -- as opposed
to the Guardian article which simply succeeds in evoking
a totally misleading vision.
After all that: I'd be grateful for a pointer to more
detailed data, as described above.
[1]
http://www.guardian.co.uk/transport/Story/0,2763,1377280,00.html
[2]
http://www.dft.gov.uk/stellent/groups/dft_transstats/
documents/page/dft_transstats_031812.pdf
(all one line)
=========================
[PS]
To come back to the opening theme,
http://society.guardian.co.uk/environment/story/0,14124,1377328,00.html
is another Guardian article today, according to which, every month,
between 304,000 (lowest figure quoted) and 12,000,000 (highest)
cubic metres of "raw sewage" are pumped into the Thames in London,
the average since Jan 2001 (48 months) being 240,000,000/48
= 5,000,000 cu.m./month
This is a daily average of 167,000 cu.m. = (55 m)cubed, not such
a big block after all (especially considering it will have been
substantially diluted since emerging from source), enough to fill
the Chamber of the House of Commons some 25 times over; perhaps
the undiluted amount at source would do the job just once.
It is also about 1/35 of the mean daily discharge of water from
the Thames (about 5,800,000 cu.m./day).
This last is one figure I can really relate to. In relation to
swimming in the Thames, think in terms of getting into a fairly
standard bath of 150 litres (1.5m x 0.5m x 20cm), to which has
been added some 150/35 = 4.3 litres of toilet flush ...
[Christmas Quiz]
It turns out to be a bit needle-in-haystack to find information
about the dimensions of the Chamber of the House of Commons.
Your Christmas Quiz is to come up with the best online resource,
and length, widdth and height.
Happy Christmas to all,
Ted.
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Date: 20-Dec-04 Time: 16:12:39
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