Some Engineering Problems Of The Panama Canal In Their Relation To Geology And Topography

RELATION OF DIFFERENT FACTORS TO ENGINEERING. Ci RELATION OF DIFFERENT FACTORS TO ENGINEERING PROBLEMS. TOPOGRAPHIC TYPES. What topographic conditions confronted the builders of the Panama Canal? The surface configurations of that part of the Isthmian land barrier that is within the Canal Zone fall under two chief types. They are: (1) The hill type of topography, developed in the interior and locally on the Pacific side and consisting chiefly of irregular angular hills, short ridges, and crooked unsymmetrical valleys and basins (Pls. I and II) ; and (2) the coastal-plain type, developed as low hills and swampy flats in the vicinity of Colon and locally on the Panama side (Pl. Ill) HILL TYPE. The hill type of topography is well developed in the central and southern parts of the Canal Zone. Ccrro Gorda, near Culebra, and Ccrro Balboa, near the old site of Gorgona, stand approximately 1,000 feet above sea level, and below this elevation are many lesser peaks. Seen from a position of commanding view, this topography is most striking in its irregularity and presents some likeness, in its green jungle-covered irregular hills and hollows, to enormous cross waves at sea. It is a type of land form not uncommon in the Repub- lic of Panama. Now, what relation does this type of topography have to canal construction? In building the Panama Kailroad and in building some of the dirt-train and other branch lines connected with canal construction the numerous hills had, of course, to be avoided, with the result that the sinuosity of the tracks added difficulties both to their construction and operation. The new line of the Panama Rail- road is relatively little curved, but it encountered some heavy cuts and fills. The canal passes between Gold Hill, 662 feet high, and Contractors Hill, 450 feet high, and a part of each had to be removed in the digging of Culebra Cut, thus adding to the amount of excava- tion. Conditions had to be studied in choosing the route, so as to strike the proper balance between minimum excavation and minimum curvature of the canal channel. On the other hand, most of the hills arc composed of tough hard rock which could not readily be worn away and cut into valleys by the streams. This stronger rock forms Gold and Contractors Hills, and these are strengthening pillars which hold back slides of weaker rocks. Ancon Hill, another high point of hard rock, furnished a convenient quarry for stone to be crushed and used in the concrete of the Pacific locks. The height and steepness of Ancon Hill is such that the whole rock product could be handled by gravity from the quarry, through the crushing plant, and then