Puslapio vaizdai
[graphic][merged small]

regions where very different measures enough to overcome the vertical height. must be taken to secure a location prac- This can often be accomplished by carticable for traffic. For instance, a line rying it up the valley on one side and at a high elevation approaches a wide down on the other. Tributary valleys valley which it must cross. The rate of can be made use of if necessary, and the descent is fixed by the established max- desired crossing thus accomplished. imum grade and the sides of the valley But at times even these expedients will are much steeper than that rate. Then not suffice. Then the line is made to the engineer must gain distance—that bend upon itself and wind down the hillis to say, he must make the line long side upon benches cut into the earth, or

rock, curving at points where nature affords any sort of opportunity, and reaching the valley at last in long convolutions like the path of a great serpent on the mountain side. These lines often show several tiers of railway one directly above the other, as may be seen in the illustrations on pages 4 and 5.

The long trestle shown in the latter illustration is an example of an expedient often of the greatest service in railway construction. These trestles are built of wood, simply but strongly framed together, and are entirely effective for the transport of traffic for a number of years. Then they must be renewed, or, what is better, be replaced by embankment, which can be gradually made by depositing

locations, galthe material

leries have from cars on

been cut dithe trestle it

rectly into the rock, the self. The trez

cliffoverhanging the roadtle illustrated is

way, and the line being interesting as

carried in a horizontal cut conforming to

or niche in the solid wall. Peña de Mora on the La Guayra and Carácas Railway, the curve of the

The Oroya and the Chimline, which in

bote railways in South that country, the mountains of Colo- America demanded constant locations of rado, was probably a necessity of loca- this character. At many points it was tion.

necessary to suspend the persons making

the preliminary measurements, from the Where the direct turning of a line cliff above. The engineer who made upon itself may not be necessary, there these locations tells the writer that on may and often must be bold work done the Oroya line the galleries were often in the construction of the road upon a from 100 to 400 feet above the base of mountain side. It must be supported the cliff and were reached generally where necessary by walls built


from above. Rope ladders were used from suitable foundations, often only se to great advantage. One 64 feet long cured at a great depth below the grade and one 106 feet long covered the usual of the road. Projecting points of rock practice, and were sometimes spliced must be cut through, and any practi- together. The side ropes were i and cable natural shelf or favorable forma- 14 inch in diameter, and the rounds tion must be made use of, as in the pict- of wood 14 inch in diameter, and 16 ure above. In some of the mountain inches and 24 inches long. These were




notched at the ends and passed through the ropes, to which they were afterward lashed. These ladders could be rolled up and carried about on donkeys or mules. When swung over the side of a cliff and se cured at the top, and when practicable at the bottom, they formed a very useful instrument in location and construction. For simple examination of the cliff, and for rough or broken slopes not exceeding 70 to 80 degrees, an active fellow will, after some experience, walk up and down such a slope simply grasping the rope in his hands. If required to do any work he will secure the rope about his body or wind it around his arm, leaving his hands comparatively free for

Denver and Rio Grande Railway Entering the Portals of the Grand River Cañon, Colorado. light work.

The boatswain's chair, consisting of a their ends knotted, is a particularly conwooden seat 6 inches wide and two feet venient seat to use where cliffs overlong through the ends of which pass the hang to a slight degree. The riggers side ropes, looped at the top, and having were generally Portuguese sailors, who

[graphic][merged small]

seemed to have more agility and less angulation, and the results were so satfear than any other men to be found. isfactory that the method may be deAt Cuesta Blanca, on the Oroya, a promi- pended upon as the best system for nent discoloration on the cliff served determining topographical data or for as a triangulation point for locating locating and constructing the lines in the chief gallery. Men were swung any similar locality. over the side of the cliff in a cage about Where the rocks close in together, as 24 feet by 6 feet, open at the top and in some of the cañons of our Southwest, on the side next the rock. This was a the railway curves about them and finds peculiar cliff about 1,000 feet high, rising its way often where one would hardly from the river at a general slope of about suppose a decent wagon road could be 70 degrees. The grade line of the road built. The portals of the Grand River was 420 feet above the river. The Cañon, as seen on the opposite page, Chileno miners climbed up a rope lad- show such a line, passing through narder to a large seam near grade where row gateways of rock rising precipitousthey lived; provisions, water, etc., being ly on either side to enormous heights. hoisted up to them. The first men When such a cañon or a narrow valley sent over the cliff to begin the prelim- directly crosses the line of the road, it inary work were lowered in a cage must be spanned by a bridge or viaduct. and took their dinners with them, for The Kentucky River Bridge, shown fear they would not return to the above, is an instance. The Verrugas work, and that unless a genuine start Bridge on the Lima and Oroya Railroad was made others could not be induced in Peru is another. This bridge is at to take their places. It is safe to say an elevation of 5,836 feet above sea-level. that 80 per cent of the sixty odd tunnels It crosses a ravine at the bottom of on the Oroya and the seven tunnels on which is a small stream. The bridge the Chimbote lines were located and is 575 feet long, in four spans, and is constructed on lines determined by tri- supported by iron towers, the central

[graphic][merged small]


one of which is 252 feet in height. The reaches narrow

gorge, a truss is construction was accomplished entirely thrown across—and the tunnel confrom above, the material all having been tinued. delivered at the top of the ravine, and the Nature's wildest scenery, the deep raerection was made by lowering each piece vine, the mountain cliffs, and the graceto its position. This was done by the ful truss carrying the locomotive and use of two wire-rope cables, suspended train safely over what would seem an across the ravine from temporary towers impossible pass, here combine to give a at each end of the bridge.

vivid illustration of an engineering feat. On the line of the same Oroya Rail- The location of a part of the Mexican road is a striking example of the diffi- Central Railway through the cut of Noculties encountered in such mountain chistongo is peculiarly interesting. Far country and of the method by which underneath the level of this line of railthey have been overcome. A tunnel way there was skilfully constructed, in

« AnkstesnisTęsti »