position. A very elaborate triumphal bridge carrying an unimportant footpath is likely to appear as absurd as a great stone arch carrying a highway over an insignificant rivulet. Unlike various structures which we have before discussed, a bridge is not seen to best advantage from the road or path which approaches it. If it be a covered bridge, or if there be some kind of pylon on each side of the way at the end of the bridge, there will be from the road a certain sense of an enframed entrance, to any one crossing the bridge, and the view up and down the water from the bridge may also in some cases be similarly enframed, particularly if the bridge is covered. It is in the views towards it across water that the bridge assumes its real value as an esthetic unit in landscape composition. (See Plates 28 and 32.) Almost inevitably it is the dominant object of an enframed composition with many lines converging upon it. Frequently tall planting on the shores from which the bridge springs will pleasantly increase this enframement and give an additional solidity to the abutment. It is never without its reflection in the water, clear or blurred as the water surface may make it, and the designer should remember that he is creating not the span of the bridge alone, but also its inverted counterpart in the surface below.

The shape of the bridge may be an arch or a series of arches, with Forms and any degree of proportion of rise and span, or it may be abutment and Materials of Bridges pier and gently cambered line of traffic-way over all, or exceptionally it may be a spider-web construction of steel cables and suspended roadway between two towers. All these shapes may be very beautiful. Modern knowledge of the use of structural steel has produced many other economically efficient forms as well. Many of them are inherently ugly; others we may learn to like, when our present knowledge of the possibilities of steel has passed into a feeling for proportion of parts as it has, long since, in the case of stone.

The form as well as the material will probably be forced upon the designer by considerations of cost, traffic, and local conditions. This form, however, should not only be actually sufficient for structural stability, but should appear to be so.† A bridge can be consistently

* Cf. Planting in relation to bridges, Chapter IX, p. 187.

For illustrations of various bridge forms see H. G. Tyrrell's Artistic Bridge Design. (See REFERENCES.)

Roads and
Paths

light or heavy, according as it may be a suspension bridge, a reënforced concrete bridge, or a stone bridge; but in each case a proportion should be preserved between the apparent strength of the parts and the work which they are doing, even though it might be structurally possible to save material at the expense of apparently functional form. If the designer has a free hand, he may choose to construct a low horizontal bridge in a flat marsh country; a high sharp-pointed arch between two rocky cliffs. If the bridge is to be considered as an architectural structure, perfect as far as may be in itself, it is certainly the fact that no bridge can be more unified than one of a single, well-proportioned arch, or perhaps of a series of arches justly related to the effect of the whole span.

Usually, even the smaller footbridges are structures for an obvious purpose, and they should be so designed. (See Plates 3 and 4.) In a rugged natural landscape, a bridge may well be built, for instance, of large rough blocks of unhewn stone, but these blocks should be laid to make a proper and reasonable bridge, and not in unequal and irregular arches, which do not make the bridge less a man-made structure, but succeed only in making it a bad structure. If it is important that the hand of man be not visible in a particular view, and if a way for traffic across a stream may be managed by means of rock masses which are apparently natural, this indeed may be legitimately done, and such an arrangement may form a very desirable feature, usually at a small scale, in naturalistic rock gardens or similar designs.

Except for the occasional use of a fallen log across a stream, it is practically impossible to make anything which could be called a naturalistic wooden bridge. It is nevertheless possible and often very effective to construct a small bridge of logs and poles, perhaps with their bark still on, which shall, by their surface and to some extent by their form, be congruous and not unduly conspicuous in a natural scene. (See Plate 12.) Usually, however, the quaint conceits of rustic work in gnarled branches and contorted roots are to be avoided, except as an occasional amusing eccentricity. Their forms are usually ugly, and they look, if anything, more like the work of man and less like natural objects than do straightforward bridges of similar material.

Roads and paths, like all the other elements of landscape composi

tion which we have been discussing in this chapter, are differently handled by the designer according as they form a part of a humanized or of a naturalistic composition.* With roads and paths, this difference is greater than with most of the other objects, because in formal and some man-made informal landscape design, the roads and paths are made to be seen and to take their part as important elements in the composition, whereas in a natural or naturalistic landscape, they are usually a necessity to be tolerated, not a beauty to be displayed. In a naturalistic landscape, as far as it is possible, the road should Roads in Naturalistic seem to lie upon the surface of the ground without interruption of the Landscape natural modeling. The surface of necessary cuts and fills should simulate the natural surface where possible; where this is impossible their modeling should still be as sequential and unbroken a continuation of the natural surface as the designer can arrange. Usually, if the road lies somewhat below the adjoining surface, it will be less conspicuous. Where a road must cross a view over an open area, in a naturalistic scheme, it may be impossible to conceal the road by planting without thereby interrupting the view. It may be still possible to lead the road across the open space in a depression, deep enough at any rate to conceal the road surface, perhaps deep enough to conceal the traffic as well, and in any case so arranged that the line of sight passes from a surface on the nearer side, related to the whole open area, to a surface on the farther side, apparently continuous with it, and the mind is thus led to suppose that the intervening surface, not seen, is of the same character.

Where a road is to be inconspicuous, its surface should be as little noticeable in color as possible and its edges should not present a clean, hard, and definite line. These considerations make the use of a road material like gravel or broken stone esthetically preferable to that of brick or cement. Asphalt-bound roads, as we have seen, may be constructed with a surface not much different from macadam, and with sufficient care the sharpness of their edges need not be too conspicuous. Such a surface may be modeled into gutters on the sides, but macadam and gravel surfaces are too soft to serve as gutters on any considerable

* For some discussion of roads and paths in the design of the estate, the park, or land subdivision, see Chapter XI.

Form of
Roads

slope. A gutter of cobble-stones or kidney-stones may be constructed which will make a sufficiently irregular line along the edge of the road. In many cases, however, the better arrangement is to throw the water off the surface of the road on to the adjoining grass surface, carrying the water away from the road, where this is possible, and elsewhere. constructing a broad, shallow turf gutter, its outer side joining the natural ground surface by insensible and varied modulations, its inner side joining smoothly to the curve of the crown of the road.

The maximum gradient of the road will be determined by the character of the traffic and the character of the road surface.* Its location upon the topography will be determined as a matter of economics by the directness and cheapness with which the road can be run to the point it seeks without exceeding the maximum gradient and without turns too sharp to be readily followed by the traffic. As a matter of esthetics, however, the road should, as we have said, seem to fit the topography with the least possible disturbance and should seem to go as directly as may be from one point of interest to another. If it vary from directness, it should be only for a sufficient obstacle, hill or valley, or outcropping ledge or foliage mass. (See Plate 15.) If the road be unimportant in character like a country lane, continuity or cleanness of curvature in its line is not essential, and indeed, often not desirable. If the road is important enough to be, whether the designer desires it or not, a considerable feature in the landscape, at least when seen by the traveler upon it, then the unity of its curvature must be considered. (See Plate 31.) Too great an insistence on this unity, particularly through considerable portions of the length of the road, may very unhappily increase the relative importance of a road which should be subordinate in a design; but sequence of curve, smoothness of flow of one curve into another, is certainly desirable, if for no other reason than its obvious adaptation to the passage of traffic. When a

* There is not space here for a discussion, at a scale to be useful, of the interacting economic considerations of road-gradient, cross-section, and surface in relation to the various traffic requirements, flow of surface water, sub-surface utilities, and cost of construction and maintenance. For discussion of these topics, particularly in relation to larger public roads, see such books as Blanchard and Drowne's Highway Construction or Frost's Art of Road Making.

road turns about an obstacle, it should not of course turn so sharply as to discommode the traffic; on the other hand, having turned as sharply as it conveniently can, it should set off directly for its next necessary point of turning and should not lie upon the landscape in a series of broad and unnecessary loops. It should be remembered in designing a road on plan that it is seen in reality in sharp perspective, and that a slight curve, so long as it is virile and definite, is likely to be of sufficient effect.

sections

Where a road comes into or intersects another, the first considera- Road Intertion is the smooth flow of traffic in plan and in profile from each road into the other. The practical considerations, then, of gradient, pos

sible radius of turning of an automobile, and view from one road to another to prevent accidents, must come first. If the curved continuation of the side-line of one road into that of another undesirably increases the road surface at the junction, then it may perhaps be well to lead the roads into each other by still more gentle curves and so to produce islands between the branches of the roads, which may be covered with low planting to conceal any undue amount of road surface. (See Drawing XXVIII, above.)