The final effect would be the relief of congestion upon the typically narrow winding roads which cover the surface of England. They would be relieved, in the case we have quoted, not only of the great mass of urban traffic between London and Birmingham; they would be also relieved of the very considerable local traffic—not entirely relieved, of course, but relieved in a proportion large enough to make a very sensible difference to modern communications.
Though the thing still remains pure theory and though the political and social obstacles to it are very serious indeed (any trajectory you name in this crowded island would destroy much which all our people—let alone the owners—love to preserve), yet it is worth while to analyse the conditions of such roads, because only thus can we establish the main rules which, under whatever modification, must ultimately govern the change that should come.
iii
We need five things:
(1) A very strong foundation, upon which depends—
(2) A permanently good surface;
(3) The avoidance of sudden curves (in which is included the avoidance of obstacles hiding the approaches to any curve);
(4) Great width;
(5) A fifth point, almost as important as these first four, the necessity for the providing of crossings. The great arterial road reserved to the internal combustion engine would be, for people who had to cross it, an obstacle a great deal worse than a railway. Our forefathers protected in all sorts of fashions the road crossing the railway at a level crossing—by insisting on gates and an attendant, by compelling the road, if possible, to pass above the railway upon a bridge, and so on. More attention was paid to this point in England than in any Continental country, and we benefit by the results of that care to-day. But the arterial road would be far more dangerous. It would have a continual stream of very rapid vehicles in both directions, and the scheme had better not be envisaged at all if the cost of providing for cross traffic is not faced. The problem is by no means an easy one. It means, necessarily, embankments for bridges, or tunnelling, at every crossing, and these will have to be more numerous than the road crossings: they will have to serve rights of way and private approaches as well. I think it will be found, when the scheme is first attempted, that this obstacle will prove the most serious of all.
It is for experts in the science (of which I know nothing, and allusion to which I have therefore kept carefully out of this essay) to decide what these details of surface, width, foundation, etc., mean in practice: their expense and character.