Tales From The Riverbank
In the summer of 2003 a simple stone bridge over the
Wiltshire Avon shared some of its secrets, 600 years ago one could journey
from the Hindu kush via mainland Europe to plantaganet England crossing
rivers by stone packhorse bridge designed & constructed from the same
pattern book as used in rural Wiltshire.
The bridge forms part of a astonishing wider complex of buildings, with
its famous tithe barn and associated agricultural buildings, Barton Farm
Grange formed part of a great estate owned by the powerful Abbess of Shaftesbury
which spread across much of the west country. The bridge is approached
from the nearby Cotswold scarp with its cornbrash geological formation
(which is particularly suitable for growing cereals as the small, easily
frost fractured stones near the surface provide shelter for germinating
seedlings). The Abbess would have collected a tithe or a proportion of
cereal from her tenants to fund the church and this grain would have been
collected, processed and stored at the newly built tithe barn. It is illustrative
that the quantities of grain being collected & carried would have been
so large that in bypassing the existing town bridge (with its toll levied
by the local corporation) a considerable cost saving would have been anticipated
even after the huge expenditure of building a new bridge (although the
Abbess did own the local quarries & land).
The bridge spans the river with four pointed arches. Three cutwaters were
added to the upstream side in the 15th century and railings added in the19th
century.
By 2003 The bridge was getting rather tired and in need of some care & repair.
The company which I run with my partner Andrew Sharland, Minerva Conservation,
was awarded the contract for works, church repairs are our staple however
we do enjoy the additional challenge of maintaining our conservative philosophy
on structures as environmentally akward as this. The structure was exclusively
used by pedestrians so Wiltshire County Council were able to adopt a more
hands off approach than it usually would toward bridges carrying vehicular
traffic. 
As
is usual with projects of this nature previous inappropriate attempts at
renovation had to be undone. Using an surprisingly stable pontoon system
we Peeled back the layers one by one, removing areas badly damaged and
jacked up by tree root growth, poor quality stonework & inappropriate
modern materials previously fixed by contractors in the 1970s from a rubber
dingy, (yes, its true ive seen the photos). We also removed the cracked
Tarmac carriageway and dismantled the cutwaters, again to remove trees!
Having previously worked extensively on the adjacent C18 Kennet & Avon
Canal it was a surprise to see many similarities in construction, Why bother
using lime mortars as a bedding & packing material when abundant locally
sourced clay would suffice? It is waterproof, works well in compression,
Much original stonework survived in the arches as
was evident by the adze marks left by the masons
who had quarried the stone only a couple of hundred
yards away, The fixing of the replacement stone in the barrel vaults could
only commence once the resident Daubentons Bat (also known as water or
fishing bats) maternity roost and their fledged young had been temporarily
moved on to the surrounding poplar trees.
Consecutive long evenings were
spent on the pontoon with the local bat expert while he sealed roost holes & cracks
(once the little critters had left to hunt for the night) this attracted
the local drunks & constabulary in equal measure and ensured a regular
food supply for the local invertebrates. Night was when the river really
came alive, a primeval soup of midges that appeared at night lived just
above the river & kept the large bat population well fed, by day squadrons
of damsen & dragonflies along with the odd kingfisher would alight
on the pontoon. Roosts
were recreated within the fabric of the arches and batboxes were created
within large lumps of ashlar which have now been successfully colonised.
Temporary formwork in the barrel vaults supported
stones adjacent to replacement elements. Limpley
Stoke Ground limestone was found to be a ideal match & was
cut, dressed & fixed by colleagues with whom we had worked at our
time at Salisbury Cathedral. The bridge was repointed & grouted using
a naturally hydraulic lime mortar (NHL5), a Cotswold limestone Thames aggregate
from Moreton Cullimore created a satisfying and texturally pleasing mortar,
it wasvital that we used a heavy duty mortar which could be guaranteed
to have achieved a set properly before the winter with its frost & floodwaters
which regularly rise above the bridge handrails.
Research into past surface materials of the carriageway suggested that
it was originally paved with crushed limestone which was replaced with
stone setts in the 19th century. The tarmacadam surface which was put on
in the 1940's was replaced with hydraulic lime concrete. This has created
a hard, durable surface which nevertheless allows evaporation of trapped
water in the bridge after it becomes saturated. The new carriageway is
also cambered to allow rainwater to run off via new Forest Marble cobbled
gullies. The railings are recognised as a good example of 19th century
rural craftsmanship and are in harmony with the original stonework. A new
wrought iron handrail was made and fitted on the upstream side, the railings
were left unpainted to allow the natural patina of the wrought iron to
develop
. 
In one of the Valleys feeding into the basin of the river Avon rolls
the mells river, its choc a bloc full of interesting structures that
have quietly survived here from the industrial revolution.The aggregates
levy fund has enabled us (working with volunteers and the Somerset Industrial
Archaeological society ) to begin to conserve some of these monuments,
last winter for example we begun worksto protect some Lime kilns. We
will soon be undertaking some basic structural repairs to the voussiors & Cutwaters of the
lonely & now rather sad Murtrys Aqueduct of the long defunct & uncompleted
Dorset & Somerset Canal which was planned to connect the Bristol and
English Channels from Bath to Poole, via Wincanton & Frome, it dates
from 1796 and was planned to to carry coal and the locally produced products
of Fussell's Iron and edged Tools over the Mells River.
A few hundred yards down strean sits Murtrys Packhorse
bridge, essentially C14. two of the original three
slightly pointed ribbed arches, remain, the bridge
was widened in 1817 but became obsolete when the railway
constructed a new bridge in about 1854. Sucessive winters
are now taking their toll and recent temporary protective
works are being washed away. It awaits further funding.
Another blessed business is bridges to make
In places uncrossable after great showers
what a pity to pull a dead body out of a lake
Who was baptised in a stone font, a fellow of ours
C15 poem recorded by Leland on his travels commemorating the construction of a new bridge
Barton Farm Bridge as it is today.
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