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Dorset Diggers CAG

#01 Thoughts on Roman Transport Strategy in Dorset and South Somerset

The water debate, Richard Hood : February 2015

This article was prompted by my reading of Raymond Selkirk’s 1983 published book The Piercebridge Formula.  In this book Raymond provides evidence that many of the Roman forts in the north of England were serviced by the canalisation of existing waterways and more controversially that the Romans used pound locks, generally not thought of being in use until the building of the Exeter canal in the 16th cent.

The figures quoted here are from the book in question and I have not verified them back to their original source.

Roman roads in Britain are considered to have been built by the military for the military.  They were primarily for the fast movement of troops and the speedily despatch and receipt of important documents.  They were where possible straight, built up steep gradients to climb hills, not very wide and to take a maximum load of 1500 Roman pounds, 1000lbs.  This meant they were not well suited to the movement of heavy goods that would be needed to supply permanent forts or expanding towns.  Large mules could carry a load of about 270lbs and the largest wagon pulled by oxen, the Plaustrum, could carry 1000lbs. Heavy wagons may well have had problems ascending and descending steep hills.  Faster four wheeled carts such as the raida had a capacity of  667lbs.   Marching troops would not be pleased to have to pass slow moving vehicles on route and due to the Roman road type of construction, with ditches either side of the road, it would be difficult to park carts out of the way.

This brings us to the alternative as suggested by Raymond Selkirk; water transport.  Though the Piercebridge book only concerns itself with the north of England I have looked at the rivers of Dorset and South Somerset on both maps and Google Earth to try and see if they may have been suitable with some degree of canalisation to supply forts and towns.  Even if we ignore the possibility of the Romans building pound locks, some straightening and the construction would have been needed.  This may not however have been more costly than road construction, where every foot of road has to be built from scratch.

The first river to be considered and probably the favourite would be the Yeo to Ilchester.  At present the Yeo leaves the river Parrett just south of Langport and continues about 8 miles to the Roman Oppida and fort of Ilchester.  Langport was the limit for seagoing ships in medieval times and was probably the limit for the Roman large vessels.  The river today is reasonably straight and has three weirs.  I would suggest that a load on a boat of up to 5 tons would have been possible to Ilchester.  From Ilchester the river becomes twisty with the sites of old water mills and weirs.  It would however probably been possible to take a load of a ton to a landing where about 50 soldiers would have been sufficient to carry goods up to the fort at Nether Compton.

The river Frome from Wareham to Dorchester seems a less likely candidate.  It meanders along its course to the sea and though the straight distance from Wareham to Dorchester is about 15 miles the river distance must be nearer to 40.  There is no sign today on Google Earth of any straightening that would have made the river more navigable and with a drop of about 30m a number of weirs would be needed to be  constructed.  At least there are a number of weirs still extent.  Perhaps the biggest problem is that Dorchester is only about 8 miles from the probable Roman port of Weymouth, though there is a steep climb of 140m to be conquered leaving Weymouth. 

Another contender is the river Stour from Christchurch to beyond Wimborne.  This river is also bendy today, however there are signs of dried up cut offs.  The river is of a fair size up to the Roman fort at Lake Gate just south of Wimborne and the large Roman fort at Crab Farm near
Shapwick.  Again the problem may be that Shapwick is only about 8 miles north of the Roman port of Hamworthy, making a fairly short road trip.

The last large river, the Avon from Christchurch, does not travel near to a Roman fort though it does eventually meet a major Roman road at Salisbury.  Though not promising as a major means of water travel it is interesting that along the banks of both the Stour and Avon have been found both Iron Age pottery and coinage that could have been brought along the rivers in small boats in the Iron Age. When Josiah Wedgwood transferred the transport of his pottery from pack horses to barges, the cost of transport fell dramatically as did the number of breakages.  One thing that may help in considering the use of rivers is that they seem to have deteriorated with time as they have silted up and 1500 to 2000 years ago may have been more navigable than today. 

The last rivers to be considered are the Axe and the Isle.  There were Roman villas near to the Axe at South Chard and at Wadeford about two miles from the Isle, which itself flows into the river Parrett, they could have been used by small craft similar to the Parrett Flatners, a 20 foot boat, which were navigated on the Parrett and its tributaries for many years.  

To give some indication on what could be carried on a small river, some quick calculations would indicate that a 6m long by 2m wide flat bottomed boat carrying a metric ton of goods would draw about 125mm of water. A crew of four could easily tow this up river and could unload the goods at weirs before dragging the boat over the weir and reloading.  This compares favourably with the loads carried by carts and the cost of beasts for haulage and their feed.  Slaves for hauling boats would have been relatively cheap in the Roman Empire. 

I hope this article is of interest and might lead to some debate on the subject.