« AnkstesnisTęsti »
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.
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 the material from cars on the trestle itself. The tre 3tle illustrated is interesting as conforming to the curve of the line, which in that country, the mountains of Colorado, was probably a necessity of location.
Where the direct turning of a line upon itself may not be necessary, there may and often must be bold work done in the construction of the road upon a mountain side. It must be supported where necessary by walls built up from suitable foundations, often only secured at a great depth below the grade of the road. Projecting points of rock must be cut through, and any practicable natural shelf or favorable formation must be made use of, as in the picture above. In some of the mountain
locations, galleries have been cut directly into the rock, the cliff overhanging the roadway, and the line being carried in a horizontal cut or niche in the solid wall. The Oroya and the Chimbote railways in South America demanded constant locations of this character. At many points it was necessary to suspend the persons making the preliminary measurements, from the cliff above. The engineer who made these locations tells the writer that on the Oroya line the galleries were often from 100 to 400 feet above the base of the cliff and were reached generally from above. Rope ladders were used to great advantage. One 64 feet long and one 106 feet long covered the usual practice, and were sometimes spliced together. The side ropes were and 14 inch in diameter, and the rounds of wood 14 inch in diameter, and 16 inches and 24 inches long. These were
Denver and Rio Grande Railway Entering the Portals of the Grand River Cañon, Colorado.
their ends knotted, is a particularly convenient seat to use where cliffs overhang to a slight degree. The riggers were generally Portuguese sailors, who
The boatswain's chair, consisting of a wooden seat 6 inches wide and two feet long through the ends of which pass the side ropes, looped at the top, and having
seemed to have more agility and less fear than any other men to be found. At Cuesta Blanca, on the Oroya, a prominent discoloration on the cliff served as a triangulation point for locating the chief gallery. Men were swung over the side of the cliff in a cage about 2 feet by 6 feet, open at the top and on the side next the rock. This was a peculiar cliff about 1,000 feet high, rising from the river at a general slope of about 70 degrees. The grade line of the road was 420 feet above the river. The Chileno miners climbed up a rope ladder to a large seam near grade where they lived; provisions, water, etc., being hoisted up to them. The first men sent over the cliff to begin the preliminary work were lowered in a cage and took their dinners with them, for fear they would not return to the work, and that unless a genuine start was made others could not be induced to take their places. It is safe to say that 80 per cent of the sixty odd tunnels on the Oroya and the seven tunnels on the Chimbote lines were located and constructed on lines determined by tri
angulation, and the results were so satisfactory that the method may be depended upon as the best system for determining topographical data or for locating and constructing the lines in any similar locality.
Where the rocks close in together, as in some of the cañons of our Southwest, the railway curves about them and finds its way often where one would hardly suppose a decent wagon road could be built. The portals of the Grand River Cañon, as seen on the opposite page, show such a line, passing through narrow gateways of rock rising precipitously on either side to enormous heights.
When such a cañon or a narrow valley directly crosses the line of the road, it must be spanned by a bridge or viaduct. The Kentucky River Bridge, shown above, is an instance. The Verrugas Bridge on the Lima and Oroya Railroad in Peru is another. This bridge is at an elevation of 5,836 feet above sea-level. It crosses a ravine at the bottom of which is a small stream. The bridge is 575 feet long, in four spans, and is supported by iron towers, the central