OCR

Earthwork The major portion of the earthwork was carried out with rubbertired machines. On the other hand, in the bad terrain which was found at the bottom of some ditches, it was necessary to use caterpillar tractors with scrapers and even draglines. The compacting done by the earthmoving equipment was deemed to be sufficient, with the exception of the upper portion of the fills, which had to be specially compacted. Although this work did not run into any particular difficulty up to Station PK 135, this was not the case from there on. The presence of terrains impregnated with water and quicksand rendered the performance of the earthwork extremely difficult and necessitated security measures which completely changed the face of the project. At numerous points, some excavations had to be considerably widened in order to permit the building of ditches and retaining wall gabions. The cut slopes also had to be flattened, sometimes two and one-half to one, and intersected with large berms to improve their stability and reduce the action of erosion. In certain places the bottom of the excavations had to be completely cleared of muddy earth and refilled with considerable quantities of laterite materials in order to make a sound sub-base for the railroad track. This additional work considerably increased the volume of the earthwork forecast in the original plan, bringing it up to 11,400, 000 cubic - meters. Laying the Track The tracklaying was done with a gantry crane, traveling on the roadbed and transporting the 24-meter track panels fabricated in the shop. These panels were brought to the worksite by trains of lorries, on which they were stacked in groups of six. The traveling crane, with the help of two electric hoists, lifted the top panel, moved forward 24 mts. and placed it on the road- bed; after straightening and connecting it to the preceding panel, the load was moved forward 24 mts . and the operation repeated. The laying operations were followed by the welding of the track in sections of 144 mts. in length. After the ballasting was completed, these sections were then welded together from station to station, except on certain of the curves. The ballast, which was fabricated at Station Km. O, was hauled at the rate of 40 cars per day. The ballasting was done by the successive use of light tampers and heavy tampers to complete the tamping. The general progress of the tracklaying worksite attained a rate of 1,000 mts. for each 8 hours worked.