A simple procedure could save many villages from being off during the monsoons
THE rural areas of developing countries
disadvantaged in many ways, one
rthem being access routes. Heavy
and flood conditions completely
Mdcte these remote villages when
Coa h roads are either washed away mud-swamped.
Richard Tufnell, International
R%C;@nator of the Dry Stone Walling
*Avociation of Great Britain has
a method which easily
mes the problem (Appro-
ftpeoTe,hnology, Vol 22, No 1).
Tafnell's option requires proper
"brPnisation and a little hard
work for a short time to build an
"Sorroach road which could
'n-andle traffic to and from
!11-oftages for many years with
minimal maintenance.
The dry stone causeway, as
the method is called, is similar to
Lb@w-bridge as it serves the same
arpose, but - it can be built on the
ftomagers' initiative using locally avail-
ahk material. This is not only inexpen
; @ut also does not require any engineering skills. About a hundred people
required to accomplish the feat in a
week's time.
Volunteers are first separated into
main groups - 'the stone gatherers
the builders. Each group has a
er to ensure proper management
organisation. The stones are
Led ftom nearby fields and should
cally be of three sizes. The sides of
causeway are made up of large,
11@vy boulders. Stones of sizes ranging
Ithat of a football to an orange
used for the centre of the causeway.
levelling purpose, small-sized
nes are required. The total weight
all stones collected should be
about 150-200 tonnes. The next step
Mvolves the marking of the site of the
useway. It could be the old track site
a new site where the river flows
4rough rocky outcrop or surface, not
1=1kr from the original path. Strings now
A causeway sketch: allowing free movement
have to be pegged to delineate the
causeway area.
The string is held horizontal to a
height of 30 cm from the river, on either
sides of the bank, by two individuals.
Once the first string is pegged to th?
ground, seven metres or seven large
paces are measured in the direction
where the causeway width is to lie. This
string is also pegged in the same
manner, but extra precaution is to be
taken in this case as the two strings have
to be at the same level.
The building process begins with a
large boulder being placed along the
string so that its top reaches the string
without actually touching it. The boulder can be pinned into place with the
help of small stones which are wedged
in the available gaps. Similarly, another boulder is placed close to the first one, making sure that the two are touching
each other and the gaps again filled up
by wedging stones in between. This is
done till a gap of 1-1.5m remains in the
centre. This gap is used for laying the
drainage pipeline.
The pipeline is placed in the centre
of the stream to deal with low volumes
of water and prevent silting of the causeway. Some 13-14 corrugated metal half
sections of diameter 60-70cm. are placed
in the middle of this drain. Each section
overlaps the one in front by some
20cm. This helps to lock them together.
Once the drain is laid, the layer is
completed by placing boulders
to lock the drain in place and the
centre of the causeway is filled
up with stones. These should
reach the height of the boulders,
but not above it, forming an
even level layer. The strings
are again raised by another
30cm over the boulders to form
the second layer. The same
procedure is followed with the
exception that the upper
boulder should rest on two lower ones. This is known as
'breaking the joints'. The procedure is
once again repeated to form the third
layer.
The final layering is done using
small stones and chippings to bind the
gaps and to give the causeway a smooth
appearance. Maintaining the causeway
involves annual repairs which must
be carried out each year before the
monsoon season.
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