_The Special Expenditure due to Forest: Roads which Skirt Woodlands:
Roads which have been Deflected by Forest: Proximity of Material
as a Final Main Cause Modifying the Trajectory of a Road: Cost of
Transporting Material and its Effects in Ancient and Modern Times._
i
The obstacle of vegetation, which is our next cause modifying the
trajectory of a road, is two-fold. There is the obstacle presented by
forests or permanent vegetation (which includes in some climates very
high grasses) and the obstacle presented by intermittent growths. We
are not, in this country and in modern times, well acquainted with
the obstacle of vegetation to a road and with the modification of
trajectory which it imposes. We have no _large_ forests left: we have,
in common with all Northern Europe, no exuberance of growth. The dense
population and very high road mileage of modern England have put this
factor in the development of communication out of sight, and it is so
unrecognized that the mention of it here may seem superfluous. But
it is still a grave element in the calculation of a road even in the
European world, and a graver one in the new countries. And it has
had its part in framing our own system in its earlier stages. In damp
tropical countries it is all important, and even in temperate climates
where large forests exist it has its place.
(a) _Forest._ Two special expenditures attach to this obstacle: First
the effort of clearing a way, second the effort of maintenance, and
particularly through the effect of wood upon surface. The effort of
clearing, always an expense, made the forest in very early times an
insuperable obstacle to any great or considerable road. The forest had
tracks, but the main road was compelled to skirt the denser woodland,
or at the least to take a tortuous trajectory for the advantage of
natural clearings. With the development of civilization that difficulty
disappeared, and it disappeared early, although I can call to mind
no broad primitive track through any dense woodland. The Roman roads
hewed their way through forests where it was necessary, and found in
the value of the timber felled an economic compensation for the effort
made. But even with them, and even with modern roads, it remains true
that the forest governs and modifies road construction. There is case
after case where a Roman road, and even a modern road, will skirt a
forest rather than be at the effort of overcoming the obstacle: for
instance, the case of the forest of Mormal in Northern France. Here
the main Roman road from the centre of Northern Gaul to the crossings
of the Rhine cuts along the edge of the great wood like a knife, with
no growth on its western side. Further, cause and effect reacting on
one another, the lack of roads preventing clearing, and the lack of
clearing keeping down habitation and so ways, there is no great forest
possessing a system of roads anywhere in Europe. All considerable
stretches of woodland, where agriculture or other economic effort has
not cleared them, have a minimum of roadway.
In our northern climate, the larger stuff once felled, upkeep is not a
grave economic matter. The use of artificial material, which comes in
at the very first stages of road-making, renders the problem here even
less important. But in other climates, and particularly in the tropics,
it becomes the dominating factor. There are whole districts--as,
for instance, on the Amazon basin, or, again, in Central and West
Africa--where the problem of communication consists not in the cutting
of the original track, expensive as that is, but in its maintenance;
and in the greater part of those districts even modern civilization,
with its immense material advantages, and with its strong economic
inducement to the transport of tropical material, has been unable or
unwilling to make and maintain forest roads, at any rate for ordinary
wheeled traffic.
With the railways it is otherwise. The economic effort required for the
construction of the track is such that the added expense of clearing
the forest is a much smaller fraction of the whole, and the type of bed
which has to be established for the track partially solves (but only
partially) the question of upkeep. Even the railway can be overcome by
the vigour of tropical vegetation, but it has a better economic basis
in the densely wooded country than has the Road.
One of the most curious facts in the history of roads due to the
obstacle of wood is the deflection of the Roman Road through this
cause after the decline of civilization. One can find many instances
of this even in England, light as is the afforesting of this country,
and small as are the districts affected. Thus the Great North Road
making for Stamford is a broad, unmistakable way raised high above
the neighbouring country, and looking like some great double rampart,
from the crossing of the Welland for miles to the north and west. It
approaches a small patch of wood on a hill and disappears. It remains
lost for a mile after its destruction by the wood, and is not found
again in anything like its earlier sharpness of outline till Stamford
is reached. That is because the upkeep through the wood became too
difficult in the Dark Ages, and men turned the obstacle by developing
a new road round it. Another very clear example is to be found on the
Stane Street north of Eartham, where the great _Nore Wood_ through
which the Roman road was driven usurped it in later times, overgrew
it, and deflected the modern road round by Duncton Hill. We have here
probably not so much a case of keeping down the new growth as of the
wetness of the track when artificial material ceased to be used, and of
the difficult going thus made between the trees. The occasional fall
of trees across the road left unremoved, and the danger in such times
from any close cover must not be neglected. But, whatever the cause,
woodland perpetually deflects a Roman road after the breakdown of the
old civilization. It deflects it almost as often as does the marsh of a
river valley.
(b) The obstacle to the making of a road due to intermittent
vegetation is one which plays no part in our system, and is unknown
to our climatic conditions. Nor is it of any great effect save in a
few special highly characterized regions of the world. The track,
once established, can commonly keep down even the riot of spring
vegetation in open land. Such exceptions as there are, due to the
exceptional development of grasses, affect no part of the world where
communications need high development. The factor exists, but needs no
more than a mention.
ii
The last main cause modifying the trajectory of a road is the relative
proximity of material for its construction, using the word “proximity”
in the wider sense to include all economic effort: what to-day we call
the “cheapness” of the material.
Even in the very simplest and most primitive form of roadwork
material enters. There is always the necessity of hardening some bit
of soft ground or of smoothing some bit of unevenness, and from the
beginning of travel you have had the transportation of material to the
established road for the improvement of its surface, for the bridging
of its water obstacles or flooring of fords, for the making of its
causeways over marshes.
In what may be called the middle period of road construction--that is,
in periods of high civilisation, but civilisation not provided with
modern instruments--the immediate neighbourhood of material introduced
a considerable modifying factor into the trajectory of a road. This
was often masked, from the fact that the same soil which provided good
going and therefore developed early tracks usually also provided, in
the nature of things, good material for hardening the surface, for
the building of causeways, and even for the throwing of bridges. It
was also masked by the fact that the bridge, if it were to be built
of wood, could get its material from a considerable distance, as the
river was its avenue of supply. But though transport of material has
gone through a revolution in the last hundred years, and material for
road-making is now brought half across the world (_e.g._ Colonial wood
pavement), yet the way neighbourhood of material tells can still be
seen everywhere upon the road map of Europe. Thus the absence of main
roads in the Fens for centuries was not only due to the necessity of
continual artificial work, embankments, and bridges (this would not
have deterred the Roman road-makers nor the great effort of the early
Middle Ages from attempting a full network of roads). It was rather
due to the absence of hard material. And you have the same phenomenon
in the Landes of South-western France, where to this day only one
great road serves an immense district whose loose and sandy soil fails
to provide a cheap and sufficient material. The traveller in Holland
notices the same thing: here are roads ultimately depending upon brick
paving and narrow, where, had there been abundant material available,
they would have been broad, for they had to carry a great deal of
traffic. The alternative water traffic by their side was largely
developed by the difficulty of making the road.
The Romans fought this difficulty with singular tenacity. They made
all their great public constructions to last, as it were, for ever;
and they made their roads with such a strong political and military
object that they would not be deterred save, as in the Fenlands, by
the gravest difficulties in the obtaining of material. Thus in such of
their roads as start anywhere near a sea-beach of shingle you will find
them using that material up-country for miles, and they will make deep
foundations for roads that have to cross clay, using, sometimes, hard
stone brought over a couple of hundreds of miles of sea and some thirty
of land travel. It is a difficulty which has not disappeared to-day.
It has been very greatly lessened by modern means of transport, but it
still appears. We see it throughout modern Europe: for instance, in the
varying surfaces of the different soils. The ideal surface of broken
granite is not nearly universal even in England, as one would think
modern transport would have made it long ago, over such a small area
with such masses of granite close at hand and accessible by sea. The
relative cost of transport still makes diversity of surface the rule.
One can make a sort of economic barometer based on the use of granite.
It extends farther and farther from the sources of supply as public
wealth expands, and recedes towards them as public wealth diminishes.
We have a first-class example of this in the case of flint versus
granite. Flint has its advantages over all other material in hardening
a roadway. It is at once hard and easily broken: it is superficial, and
therefore cheap: it is abundant in supply in the districts where it is
used. On the other hand, it has the gravest possible disadvantage for
modern motor traffic, which is its effect upon the tyres indispensable
to that traffic. One could draw a graph, I think, to cover the last
ten years showing the fluctuations of this material and granite upon
the main roads of Southern England, and the curve would follow the
opportunities of supply and of public expenditure as affected by the
Great War.