OCR

Hard Rock-- Mainly granites, diorites, anesites, and breccia pipes. Some 72% of the total excavation required was encountered in the two latter categories of material. Final quantities, based on a design cut section of 4.40 meters bottom width with slopes as steep as material would stand and a fill section of 5.0 meters top width with 1 1/2 : 1 slopes, are as follows: Cut 792,5GB cubic meters ( ,146,305 CY) Borrow - 863,415 cubic meters (1,139,347 CY) Detail of further design criteria for the railroad: Maximum adverse grade, Smelter to Mill, 3% Maximum adverse grade, Mill to Smelter, Maximum curvature, 20° or 87.5 meter radius, grade compensated 0,04 percent per degree. All curves spiralled, maximum superelevation, 2 l/2". Original location plans called for a total of 7 tunnels and approximately 13,000 cubic motors of rubble masonry retaining walls; however, careful field line relocations eliminated all such structures. One bridge was constructed along the line at the Ilo river crossing on the coast. Two hundred and eighty foot in length from abutment to abutment, the bridge was of conventional plate girder design, eight spans of 35 ft. each supported on reinforced concrete piers, The bridge was full timber docked for emergency road vehicle traffic during periods of high water. Some l,647 lineal meters, or 5,400 lineal feet, of various size culverts were installed under fills, detail as follows: Reinforced, concrete culvert, double 4' x 6' box 60 L.M. Corrigated metal pipe culvart, 2l" and 30" diameter l/5 L. M. Corrugated metal pipe culvert, 48" diameter 840 L.M. Multi-plate pipe arch cuivert, from 6'-4' span & 4'-9" rise to 12'-4" span a 7'-9" rise 602 L.M. Total for 32 culverts 1,647 L.M.