The Road — Story, Setting & Ideas

vantage of a gradient was avoided at great expense because a mass of traffic and merchandise made it worth while. London Bridge was carried on a great number of arches precisely in order to avoid this element of gradient. A side-effect of this was the blocking of the stream and great difficulty for boats in “shooting” the arches on a tide; but this drawback to river traffic was thought worth while as the price of a level road.

Another reason which often led to the expensive flat stone bridge was its replacing an old wooden pile bridge. The wooden pile bridge had no cause for creating a gradient. On the whole it was cheaper to keep it exactly level, and as low as possible consistent with the rise of the water. Where such a structure had preceded a stone bridge the habit of a level road was continued, even at the expense of many piles and arches.

A third effect of the bridge upon the Road, also due to its comparative expense, was the convergence of roads towards bridges, established or even only planned. You will perpetually find up and down Europe the approaches to a town from two or more directions merged into a common road just at the entry to a bridge, in order to save the expense of two crossings, though at an extra expense of space and time; thus, Abbeville, Caen (a very striking example, with _three_ converging roads on each side of the bridge), London--the chief example in Europe--Saragossa, with the two main roads from south and west converging on its bridge--all “gather” roads after this fashion.

But the effects of the bridge upon the mere trajectory of a road, upon its surface and contour, were far less than were its political and military effects. Though land armies were always tied to roads more or less, it was possible to leave the road for short distances under stress or for the sake of strategy. Cavalry continually did so for great stretches, and infantry could do so occasionally. But a bridge acted like a magnet. The defence of a bridge was the defence of a point which an army in force was always compelled to use, and the term “bridge head”--that is, the holding of the space on the _further_ side of the bridge, thus commanding the passage--is an example of its permanent military function.

A bridge was, for the same reason, a natural place of toll. Merchandise had to use it, and the same requirement of continual repair which often entailed a permanent post at a bridge gave the opportunity for using that post for the raising of taxation. All through the end of the Roman Empire and the Dark and Middle Ages this function of the bridge is most prominent.

But most important of all the effects of the bridge is its creation of a _nodal point_, that is, a knot or crossing of ways. The bridge effects this in two fashions: firstly by that tendency to a convergence of roads upon the bridge which I have just noted, and secondly, and much more important, by the transverse of the bridge and the river. A river is also a high road if it is in any way navigable. Therefore, wherever a land road crosses a river and establishes a bridge you get a crossways of communications. At such a point, where many avenues of approach meet, and whence opportunities of travel to different places radiate, you have what is called in political geography a Nodal Point.

Now, the nodal point is of such importance that it merits particular attention. The nodal point, especially if it is established by a bridge, has two great functions in history. It determines the strategy of campaigns (and alters even the tactics of actions), it determines the growth of towns. It has been said that London was made by its bridge. Whether there was a settlement (there probably was) upon the gravelly hill which approached the river from the north, before any bridge was thrown across the tidal Thames, we do not know; but it is certain that the throwing of this bridge gave London its opportunity for development, and what is true of London is true of Paris, of Rouen, of Maestricht, of Cologne, and of twenty other great urban centres in our civilization. Strategically, a commander holding a nodal point retains the opportunity of moving along any one of many lines of movement, and at the same time denies the opportunity of junction to his enemies. To put it in its simplest form, a commander holding a nodal point and concentrated there can prevent the concentration of two fractions of his enemy along any two roads radiating from that nodal point. He can himself march up each of these consecutively and defeat the two fractions of his enemy in detail. That is the simplest possible case, and it can be developed into any amount of detail and intricacy.

The bridge is the point where the commerce up and down stream crosses the road-commerce transversely to the river-commerce, and the nodal point of the bridge establishes a market. But that nodal point has other characters even more important to civilian life. It creates a point of _trans-shipment_, where goods must be transferred from the water vehicle to the land vehicle. In their transference you have the political opportunity of examination and toll, and, if necessary, interception; and you also have, of course, the whole of the middleman business of dealing with and passing through the goods--you have the depot and the warehousing and all the adjuncts of a built-up commercial centre and a market.

But the bridge as a nodal point has yet another occasional function which has marked all history. That function it exercises when it is the lowest bridge upon a great navigable river. Such a bridge--the bridge of Rome for instance, the bridge of London, the bridge of Gloucester, the bridge of Newcastle, etc.--has been the making of inland ports. It must be remembered that before the advent of the railway, or at any rate before the organization of rapid and easy road travel, it was to the interest of sea-borne trade to penetrate into the heart of the country as far as possible. You avoided the cost of trans-shipment, and you had a much cheaper means of conveyance than anything that went by land. But the first permanent bridge across a waterway blocked the further progress up-stream of sea-borne traffic. Therefore there was a tendency to keep this first bridge well up-stream. Further, whenever it was made, it tended to create a glut of traffic at this point of section. The cargoes from the sea came here and could go no further, and this last function of the bridge is perhaps of all its historical functions the most important. Even where a river is very rapid, as the Tiber, the first bridge has some effect. Where it is tidal it is, of course, as in the cases we have just quoted, of the greatest effect, and usually on the great tidal waterways the first bridge will be found not indeed at the limit of the tide, for there the water would be too shallow, but in the last reaches. There are cases (Rochester is one) where the road has proved more important than the stream, where a bridge was imposed very low down in the tideway, but it has there fulfilled the same function of creating a market and a town. There are cases (Antwerp, Bordeaux, and Philadelphia are examples) where a secure harbour and good wharfage made the inland market and town in the absence of such an obstacle as the first bridge; but in the greater number of navigable rivers, even in so narrow a stream as that of Seville, the bridge makes the port and the town, as one can see by adding to the examples already given Nantes, Montreuil, Glasgow, etc.

There is a little note on the crossing of water courses which is curious and interesting in the history of roads. Since the crossing is always an effort, or, in economic terms, an expense, to be avoided as much as possible, the Road naturally avoids a _double crossing_, but, on the other hand, an island is a stronghold, and even a peninsula where two rivers meet is a potential stronghold. Therefore you have in the history of all early European roads a sort of dilemma, the first travellers debating, as it were, whether the occasion were sufficiently important to warrant the double crossing of the stream. At Reading, Lyons, Melun, notably at Paris, and in dozens of other places, the presence of the stronghold made it worth while for the Road to visit the place in spite of the double crossing, whether to an island or to the meeting of two streams. But in much the majority of cases the Road was deflected from its simplest line to a point below the meeting of two streams so as to avoid the double effort, and the occasion explains many a deflection which otherwise would seem to have no reason.

CHAPTER III PASSABILITY

_The Choice of Soils: Following the Gravel or the Chalk: Conditions in the South and East: The Obstacle of Gradient: The Early Vogue of Steep Gradients “The Other Side of the Hill”: The Modern Importance of Gradient: Passes or Gaps in Hill Country._

To the next physical factor modifying the formula of the Road we have given the name: DIFFERENCES OF SURFACE OTHER THAN MARSH AND WATER COURSES. The differences of surface other than marsh or water courses affect the trajectory of a road in several ways: first and originally in its passability to human travel on foot or with beasts of burden, or later with wheeled vehicles, and here the two factors were hardness and evenness. But there was a great contrast in the obstacles of the North and the South of our civilization. In the North, and especially in England, damp was the enemy. For a trajectory to be used in all seasons and in all weather sand and chalk at once suggested themselves. Clay can be used only in the dry season. The various soils determined the first trackway and impose themselves visibly upon the map of our oldest roads.

For instance, the road down the upper Wey to Farnham is, in its oldest form, a deliberate picking out of long gravelly stretches in the bed of the valley. On a geological map you can trace this road picking its way from gravel patch to gravel patch almost as a man crosses a stream by stepping stones. It leaps, as it were, from one gravelly stretch to another, and in each keeps to the gravel as long as it can. For the same reason a primitive road will follow the South, or sunny, side of a wood or of a ridge of land, so that the surface may dry as soon as possible after rain.

When the use of artificial material for the surface of the track became common this question of quality of soil was somewhat modified, but its essential was retained; for what made bad going (in the North, and particularly in Britain) being heavy soil, that same kind of land, which interfered with foot or pack-horse travel, swallowed up material. It was a less grave inconvenience than in the times before artificial material was used, but it was still an inconvenience expressed in the shape of expense; and nearly all the original trackways continued to take account of this factor long after the use of artificial material had been introduced. The earliest of all, of course, follow the dry ridges, and in particular the chalk.

One may say, with slight exaggeration, that the chalk was the essential factor in the building up of British communications before the Roman civilization came. If you take a geological map of England you may see the great chalk ridges radiating in a sort of whorl from a centre in Salisbury Plain, and providing dry going to the Channel, the Straits of Dover, and across the Thames valley at Streatley right on to Norfolk.

Another example of a road taking advantage of dryness of surface is the straight line leading to Lincoln northwards, everywhere following that peculiar isolated ridge, with low-lying ground upon the left and marsh upon the right. Another very striking one is the Hog’s Back, where from one low-lying point to another (Guildford to Farnham) the primitive track deliberately rises and follows the summit of a high hill between rather than the wetter ground upon the slopes, though here there is an alternative upon the southern, or sunny, slope where the trackway leads through to St. Catherine’s Chapel. This is a modern example of the way in which a primitive track imposes itself upon posterity. To this day your motorist climbs up that roof of a house out of Guildford and goes down the steep on to Farnham because countless generations ago his ancestor could only be certain upon that height of dry ground.

In the South (which does not concern this essay) the great obstacle in the way of soil is not marsh, but sand. That is something of which we have here no experience, but the tracks of nearly all Western Islam are dependent upon it. Drift sand is not so impassable as marsh by any means, but it is terrible going. North and South of Atlas the knowledge of how this kind of soil may be avoided is half the business of establishing a primitive road.

An interesting case of surface (but one which is rarely met with in this country) common in dry countries where the rare rainfall is sudden and intense, and where temporary water courses carve out the friable soil, is the inconvenience due to what are called in some parts of the East “nullahs”--that is, the dry beds of such water courses or the sudden depressions made by what were formerly water courses now dried up through a change of climate. The banks of these are often so steep and their depth so considerable that the making of a plain, straight trajectory across such a country would, even under modern conditions, not be worth the labour expended. It would mean continual bridging, or continual embankment. One of the effects of this type of surface is the inordinate winding of all the roads, and even, alternatively, the absence of roads perpendicular to the fall of the land, and the establishment of communications along the line of fall rather than across it. One can see this very conspicuously in Morocco, where there are whole districts, a couple of days’ march across, the trails of which are determined by this accident. A special example of the same kind of thing is to be found in any hill range where a number of narrow spurs project towards the plain. The Road hardly ever runs parallel to the range across these spurs. It nearly always runs down the valleys or along the plain at their foot, and that although there be, as there usually are, in each valley centres of population which need to be linked up with the neighbouring parallel valleys.

GRADIENTS. The obstacle of gradient the “minimum of vertical effort” is the most evident of all the factors which modify the trajectory of a road; yet it is, upon the whole, the most complex. To determine the minimum of effort you have to find a formula consisting of many factors, some of which I have already enumerated in the opening words of this essay. In the first place, you have to consider the _average_ nature of the travel to be served. The Road used by men on foot without burdens, by men on foot with burdens, by pack animals, by wheeled vehicles, etc., must conform itself, on the whole, to the _least_ gradient useful to those who travel by it, but that “on the whole” least gradient is a factor by no means easy to determine. It depends not only upon the nature of the instruments of travel, but upon habit, upon vigour, and to some extent upon surface. It depends also on the proportionate use of the Road. You cannot sacrifice ninety-nine travellers to the special weakness of one.

There is also the question of durability. A primitive road, taking a very steep gradient, will be more durable than one taking a lesser gradient round the slopes of a hill and subject to falls from above and to degradation down the slope below; it will need less upkeep, for it is always shorter--and this last consideration explains what would otherwise be inexplicable: the extraordinarily steep gradients which primitive roads and even the roads of a high civilization will take.

One of the best examples of this in England is the behaviour of the Fosse Way in the neighbourhood of Radstock in Somerset. Here the original road was presumably a prehistoric track, but we know that it was carefully remodelled by the high Roman civilization. It must have been used for the great mass of travel during four hundred years from the first occupation of the West of England by the Romans about A.D. 50 to the breakdown about 450, and right on into the Dark Ages--that is, for not less than one thousand years. During the first half of this time (and especially during the first third) it had to carry the travel of a very full, well-developed, and complex society to one of the most important centres of its wealth, the town of Bath. Yet the road goes up the most astonishing gradients.

Somehow or other, these gradients were normally used--but it is a puzzle to say how. The modern road has frankly abandoned the effort, and takes a long sweep round both sides of the valley at a gradient of about 1 in 12. Even so, it is quite steep enough for our modern methods of travel.

The question of gradient is complicated, again, by another variable which makes the solution of the problem much more intricate than the discovery of minimum effort upon a particular gradient. You have to consider not only the uphill or downhill upon a given slope, but the type of further uphill and downhill to which your road, once established on that slope, is leading you. It is not enough to determine your best formula under such and such conditions of travel for overcoming one side of the obstacle. You have also to ask yourself whether, having got your best uphill road, you may not have led the traveller to an impossible position on the further side. Extreme cases of this one often sees in the Jura range, where the hills are shaped like waves in a storm: a steep escarpment upon the eastern side, very difficult to go up or down, and an easy slope upon the western. Here you have to balance the advantage of your gradient upon the one side with the advantage of the gradient that you will find upon the other, and, of course, to direct your line principally with a view to travel on the more difficult steeper side. That is why you often find yourself following in the Jura a road which goes up the easy western side by an apparently over-steep trajectory: you wonder why the road does not take some obviously easier line which lies below you. The reason you only discover upon reaching the summit and seeing the precipitous escarpment overhanging the eastern valley--your road has made for some exceptional advantage down this cliff, some cleft, which an easier advance from the west would not have hit. A balance has to be struck between the advantage of gradients on both sides of the hill, save in the rare cases where a range (such as the Vosges) is symmetrical and gives you equal gradients upon either slope.

That balance is always a matter of careful calculation. Where it has been brought to a fine art is, of course, in surveying for a modern railroad, for there the slightest differences of gradient make such a vast difference in the expense of working that the discovery of a true minimum over an obstacle of hill country is of the first importance.