practically the same as on the direct line, while at the point G it is somewhat lower, and the surface of the ground in the direction of J and K very irregular, it is quite clear through which village the main road should pass.

The route thus decided upon will therefore follow the letters A, D, E, H, F, and I to B. The point G may be connected by a line from there towards the main road A B at J or K, but as this would entail considerable extra haulage in a direction opposite to that in which the connecting road may be fixed upon, it is evident that this arrangement would affect the traffic from G to a considerable extent, and other means calculated to avoid this detour are obviously necessary.

This can be effected by laying down two branch roads G J and G K, and the point G may now be considered in as good a position in relation to the main road as the point F. It must be remembered, however, that the gradients, as has already been pointed out, from G to J and G to K are not so favourable to traction compared with the deviated part of the direct line H, F, I. The saving in transport on the shorter route will be proportionate to the tonnage carried, and assuming the distance saved to be one mile, it is evident that a saving of sixpence per ton at least would be effected on each ton of goods conveyed between these two points, which would represent a considerable sum of money per annum.

37. Laying out New Roads in actual practice. In the following instance, taken from actual practice, the object in view was to lay out a new line of communication to connect two existing roads running nearly parallel, and at a distance of about 1 miles from each other.

The existing roads are situated in separate valleys, with a hill or ridge intervening, and the only connection between them was formerly by a road having gradients at several points of 1 in 18, and at one or two points 1 in 10. By the construction of the new road a detour or saving in distance of 13 miles was effected.

The class of traffic to be accommodated consisted of fast and slow vehicles, in other words, mixed traffic, and a maximum gradient of 1 in 30 was therefore fixed upon as that fulfilling, under the circumstances, the conditions already laid down in this and the preceding chapter. Fig. 11, Plate I., shows the two existing and nearly parallel roads, A, B, C and D, E, F, while the cross road, which formed the only connection between these previous to making the new one, is shown at A D on plan. Owing to a continued and increasing traffic to and from the coast in a south-westerly direction, it was considered desirable to establish a more direct route, having gradients over which fast traffic could be conducted without much inconvenience to the prime mover. The first matter necessary to be determined was at what point the intended road should leave the existing one between A and C. Fig. 12 shows a longitudinal section of this road, and as the new road must necessarily start on a rising gradient, it is evident that

D

the most suitable spot of departure is at B, because it is the highest point on the existing road. This point, therefore, was fixed on as the starting-place for the intended road. The point of arrival on the road D F had likewise to be determined, and on referring to a section of this road, fig. 12, it would appear the further east, or in the direction of D, the junction was made, that the gradients would be flatter. No doubt this is the case, but, on the other hand, this would to a certain extent defeat the object in constructing the new road, namely, that of as direct a route as possible. By going too far in the direction of F an unnecessary ascent would have to be overcome which would only make the new road longer without any compensating advantage.

The point E was therefore fixed upon as the termination of the intended road and junction with the existing one, D F.

The first consideration in laying out a new road being that of a direct route, a trial line may be drawn on plan, fig. 11, between the point of departure B and the terminal point E, in order to show, in this particular instance, that the shortest route must be subservient to that having suitable gradients. A section of the intervening ridge between the existing roads situated in the two different valleys, made from the contour lines on plan, clearly shows that such a route is impracticable, owing to the steep ascents and descents on either side of the ridge. This can generally be seen at a glance, as the steepest parts of the surface of the ground are at right angles. to the contour lines. The route for the new road had therefore to be laid out along the slope of the hill in a direction tending towards E; and crossing the ridge at its lowest point or pass G, the line of road was then continued in a southerly direction to its termination at E.

On referring to the Ordnance Map, a reduced copy of which is shown in fig. 11, it will be observed that the summit level is 384 00 feet, while the height of the existing road at the point B is 134 00, or a difference of 250.00 feet. The approximate length of road between these points was ascertained to be about 8180 feet, giving a uniform gradient from B to G somewhat easier than 1 in 30. As this was the rate of inclination originally fixed upon, and as there would be no necessity under the circumstances to form a heavy embankment immediately south of the point B, where the ground is low, which would be the case if the maximum gradient were commenced from the existing road at that point, it was decided to lay out the portion from the point B for a distance of 289 yards with a gradient of 1 in 50.

The difference of level in comparison to the length of road also admitted, having regard to the maximum gradient fixed upon, of a short level stretch being introduced on the line of new road midway between the point B and the summit G.

The method followed in laying down the approximate route was to start from the fixed point G, and stake out the maximum gradient line, on

the surface of the ground, down hill on the north side of the ridge. A somewhat similar process was carried out in fixing the direction of the line between the summit and the point E, being the lowest point of the valley at the stream, and requiring an embankment of considerable height.

The whole length of the proposed route was then surveyed, and the horizontal position of the gradient pegs carefully plotted on the plan as shown, with dotted lines between them. The method here pursued, owing to the irregular formation of the ground, necessitated the route following a sinuous course.

The final line was then adjusted on the plan, following the position of the gradient pegs as near as possible, in giving the line a regular course with straight lines and easy curves, regard being paid, with a view to a moderate outlay of capital, to equalize as much as possible the cuttings and embankments. The alignment of this road, although following to a considerable extent a sinuous course, does not add in any appreciable degree to its length compared with a practically straight road along and down the side of the hill. A sinuous course is in most cases a decided advantage, from a maintenance point of view, as on a winding road the wheel traffic spreads over the whole surface, which seldom takes place on a straight road, especially when level horizontally.

The route was then staked out on the ground, and the final detailed or working section prepared, with numerous cross-sections taken at convenient points, to determine exactly where retaining walls were necessary to supplement the earthworks in forming the road. The longitudinal section in such cases should also have marked on it the level of the ground, the level of the proposed work, and the height of embankment or depth of cutting, at numerous points, where the level of the ground has been taken; these should be found by calculation and not by measurement from the plans.

The trial-section of this road showing the gradients is illustrated at fig. 12, Plate I., and the working-section of a portion of the road is shown at fig. 12A, Plate I. Detailed drawings of bridges, culverts, retaining walls, and the road covering should be provided, and a detailed written specification prepared showing the manner in which the embankments, excavations, masonry, and other works are to be executed.

38. The principles laid down in this and the preceding chapter equally apply to carrying out improvements of gradients on existing roads which, in hilly districts in most parts of the country, have to a great extent been laid down with only one object in view, namely, that of a direct line. The great sacrifice thus entailed, through steep gradients, in the cost of transportation, is a serious one, which could have been avoided in many cases by a little scientific knowledge of what is necessary in laying out a new road, so as to accomplish the greatest amount of work in haulage at the least expenditure of motive power. In other words, a lasting benefit would

have resulted had these roads been properly laid out when constructed, in the form of greater facility for travelling, avoiding wasteful expenditure of power in the conveyance of goods, less wear of horses, and repairs to vehicles, as well as a saving of time. The surface is less damaged by the traffic on roads having easy gradients, and involves less expenditure for maintenance.

39. Improving Gradients on existing Roads.-The following example of a cross-country road is a case in point where had the route followed the proposed line, one horse could, without any great exertion, have hauled an ordinary load, which requires two horses to perform over the existing road at present.

On the plan, fig. 13, Plate II., the existing road, so far as where the steep gradients are situated, is shown at A B, which it will be observed is nearly straight from point to point. On referring to the longitudinal section of this road, fig. 14, Plate II., it will be seen that the gradients are very steep on either side of the first ridge with a valley and ridge beyond. This case, like many others situated in similar circumstances, may be taken as analogous to the road between London and Barnet already mentioned, and as an instance of laying out a road with useless ascents when a subsequent descent must be made. The number of feet actually ascended is most unnecessarily increased when such height once gained is lost again. The improvement referred to is shown on plan, at A, C, B, fig. 13, the length of deviated road compared with the present one being about 180 yards longer. This additional length to be traversed is of little consequence, however, when the improved gradients are taken into consideration. A longitudinal section of the proposed road is shown in fig. 14, Plate II., and also the surface of the existing road is represented on the section by dotted lines.

The proposed new road, after leaving the existing one at A, branches slightly towards the west on a rising gradient of 1 in 38, and attains the ridge of the first hill at C; as the surface of the ground falls considerably between that point and D, it is necessary to introduce a minimum gradient in order not to lose any height already gained. By this means the point D is reached, where, owing to the ground rising somewhat abruptly towards the north, it is necessary to curve the line towards the east, and crossing the existing road at E, is gradually curved backwards till it joins the present road at the point B. The gradients on the deviated line of road, it will be observed, are such that a horse, by a slight effort, could surmount the steepest incline readily, even with what is usually considered a load on a level road. In connection with this subject, it is necessary to bear in mind that a horse can, for a short time, exert an effort two or three times greater than that which he can keep up steadily during a day's work. Steeper ascents for short distances can therefore be surmounted, while excessively steep ones may be overcome oftentimes by the horses voluntarily pursuing a zigzag course in search of an easier gradient.