Tunnel No. 7. Through crest of river-bluff two-thirds of a mile above Holcomb's Rock. Length, 600 feet. The total tunnel length on the first division is 4,150 linear feet; on the second division 990 linear feet, or on both divisions one mile approximately. All of the tunnel-material is limestone, except that of tunnel No. 7, which is a kind of granite. The road-bed widths used in the estimate of quantities, were for earth-excavation, 30 feet; for rock-excavation, 28 feet; and for embankment, 26 feet; and the corresponding side-slopes were mostly to 1, 1 to 1, and to 1. In many of the excavations, however, where the material would plainly be in great part rock, side-slopes of to 1 were used, and in corresponding embankment, 1 to 1. In large through cuts and tunnel-approaches, a certain depth of earth overlying rock was assumed, and the sectional area taken accordingly. The classification of excavation when to 1 slopes were used, was, in all cases, two-thirds rock. The tunnels were estimated as 28 feet wide, and 21 feet in length, or 18 cubic yards of excavation per linear foot. Masonry was estimated as 26 feet in width for undergrade, and 34 feet for overgrade bridges. At several points below Pattonsburgh where the line runs along cliffs close to the canal, retaining-walls are needed and are included in the estimate. At Lick Creek, section 4, where the embankment is over 60 feet in height, a comparison of cost of earth-work and iron trestling was made, with a result so much in favor of the former that borrowed material has been estimated for in all cases of excess of embankment on both divisions. Two exhibit-sheets accompany this report, one for each division, containing quantities, prices, and amounts for graduation, masonry, and bridging on each section; also a profile of each division, and a topographical map on a scale of two and one-half miles to the inch, showing the corresponding alignment. The field-maps, on a scale of 100 feet to the inch, showing in detail the topography and the railroad location on which the following estimate is based, will be forwarded with the remainder of the field-notes and estimate details. Exhibit of work to be done upon the first division of the United Cubic yards. Price. Total graduation to be done. States Government Freight Railroad, State of Virginia, 1874. 16 00 16.00 46,558 829 7.00 1,500, 36, 554 37, 800 158, 411 5 16.00 8,971 222, 281 1,208 3 16.00 79, 773 1,819 32, 989 632 43, 552 538 4.00 2, 152 34, 166 458 4.00 1,832 22, 446 40, 015 6 400 37, 439 680 16, 526 1, 110 439 7.00 22, 298 216 15, 593 336 8 16.00 15,728 5,485 27, 628 142 4.00 7,740 39, 886 600 1,227 7 00 193, 217 18 16.00 13, 717 74, 724 2,963 105, 696 4,000 16, 597 544 497 7. 00 7 96, 791 16 00 5, 159 16.00 39, 674 1,845 136 16.00 43, 020 1,544 105 700 3 16.00 9,505 1,463 6,676 5,556 19, 231 S. Ex. 19, pt. 2-2 TOTAL AMOUNT OF SECTION. |