ii
I maintain that of the two theories the second is just: that a gradual experimental growth in its roads, a method coincident with local caprice, burdens with imperfect communication the society adopting it; that conscious design is essential to efficiency. And this [I propose to illustrate by a single example]. Take two points A and B, such that a line joining them must lead across a marsh, a river, and a range of hills. Let some primitive wanderer make his way from A to B, knowing, when he is at A, the direction of B by, let us say, a distant peak overtopping the range between. That primitive wanderer would first of all skirt about the marsh and, finding its narrowest place at C, would set to work and make his causeway there. Having crossed it, he would come to the river. He must either swim or ford it. Supposing him to prefer, through the necessity of a pack or what not, to ford it, he casts about for a ford. He finds one at D, and perhaps he also, if he takes time to look about him, finds another deeper one at E and another at F, but as his causeway is near D he takes that ford.
Sketch I.
Then he has to make for the hills. We will suppose that the peak directing him from beyond B is still visible. He takes his new direction from it and looks towards the base of the hills at G. There, in the direct line to the peak, the contours are so steep that the trouble of getting up would more than counterbalance the shortness of the cut. He casts about for a better chance, and at last finds a gradient just worth his while at H. He climbs up that; but though the gradient is easy on the A side at H on the far side it is very difficult, so he turns along the ridge to K, where he finds an easier down gradient: a spur leads him on by its gentle slope, and from the bottom of the spur he makes straight for B, which is now right in front of him and plain sailing.
Now, look at that track as established by our primitive wanderer and see how lengthy and inconvenient it is, how ill fulfilling the object of the traveller compared with what would have been established by even a moderately intelligent and cursory survey of the ground as a whole and the making of a plan. To begin with, it would have paid our traveller to take a little more trouble in crossing the rather wider gap in the marsh at L and the rather deeper ford at F, because he would have gained very much in time and space with comparatively slight extra effort had he surveyed the whole ground and thought things out. He was only led on to the ford at D because it was suggested by the crossing of the marsh at C. The first opportunity made the second. But to continue the plan: F is nearly opposite the easier up gradients of the hills, but, having surveyed that bad steep on the far side, he slightly modifies his road, crossing the ridge at M behind a summit which hid this way from the first traveller. Then he goes down the practicable, though steep, slope at N, and so reaches B. The first road produced haphazard by successive chances gives the lengthy and roundabout trajectory A—C, D, H, K—B. The second, with very little extra labour, gives him the far shorter and better trajectory A—L, F, M, N—B.
We see from this elementary example how the thinking out of the theory of the Road is of advantage in practice. It may be urged that the discovery of advantages as time goes on gradually improves the Road, and in this way half-conscious development will always give you the best road in the long run without studying its theory. But history is against that view. Europe is full of roads thus established haphazard, confirming themselves by use and by expenditure, and for centuries neglecting opportunities which would have been present to the eye of the most cursory and moderately intelligent survey.
This conflict of principle between growth and design in the creation of the Road is at the root of half our modern crises in road-making. The real issue is between those who would gradually add to or develop from custom and those who would radically impose new plans, and on a right decision the economic future of this country may well depend.
When we come to consider even the first of succeeding modifications we see still more clearly the complexity of any road-formulæ and the corresponding advantage of plan over habit. The marsh, the river, and the hill are but the beginning of the affair. There is a modification due to the fact that the marsh may not be permanent, nor the depth of the river; that the Road may be of special use at moments when the river is shallow or flooded, when the marsh is dry or, exceptionally, impassable. There is the modification of surface. Clay, for instance, is fairly good going in dry weather, but the worst in wet. There is the modification due to vegetation: the balancing of the effort involved in going round a dense scrub against that of cutting through it and of maintaining the cutting when it is established. There is the modification introduced by the instruments and science available for construction and for cutting. In one stage of development it will pay to take a road by a bridge across a deep river where in earlier stages of development it would have been necessary to seek a ford. In one stage of development it would pay to make a cutting through a scar too steep to climb where, in a lower civilization, it would have paid to go round it. The whole formula increases in complexity the more we examine it. It is a formula for the discovery of a minimum of effort. But in the establishment of that minimum you have to consider not only a very great number of factors, but the respective value of each to the whole, and your success in establishing the Road depends upon the accuracy of your judgment both as to the presence and as to the comparative value of all those factors.
CHAPTER II
THE CROSSING OF MARSH AND WATER
Physical Factors Modifying the Formula of the Road: Marsh as the Chief Obstacle to Travel: The Political Results of Marshes: The Crossing of Water Courses: The Origin of the Bridge: The Effect of Bridges upon Roads: The Creation of a Nodal Point: The Function of the Nodal Point in History.