TUNNEL. 545 TUNNEL. Diame- ter, tt. Length, tt. Cost Capacity, gallons Lake View Chicago Ave....^ Twelfth St. or) Four-mile ( H.Tde Park or I Sixty -eighth -< St I Northeast 6 e 7 7 8 6 7 5 6 10 9,999 10,067 10,660 10,908 9,139 ) 25,200/ 12,353 8,132 V 6,026 14,108 $701,792 46-1,806 415,709 299,897 1,104,744 741,371 610,660 45,000,000 1 170,000.000 95,000,000 106,000,000 200,000,000 Total (21.97) miles.. 115,992 »4,338,939 615,000,000 rotary boring machine which cut out the passage- 1.5.92 miles of hind tunnel. The subaqueous way to full size at one operation. Except for tunnels are as follows: the Mersey Tunnel, which is a passenger tunnel, all the tunnels previously described an- for rail- way purposes. They are also all rock tunnels. Ainona the man}' important railway tunnels which have been built through .soft ground only two will be mentioned. The Baltimore Belt Tunnel, 8350 feet long, in Baltimore, ild., was excavated through water-bearing sand, loam, clay, and gravel by the German method of soft-ground tunneling. It provides for a double- track railway line. The l<nint Clair Tunnel carries the double tracks of the Grand Trunk Railway imder the Saint Clair River between jMichigan and Canada. In 18SG the .Saint Clair Tunnel Company was formed to build this tunnel. .^t jNIilwaukee, Wis., there is a water-supply Borings showed the materials to be penetrated to tunnel .3200 feet long and T^A feet in diameter be a soft blue clay throughout at the site chosen, lined with brick masonry throughout, completed which was just below Sarnia and Port Huron, in 189.5. At Cleveland, O., a water-supply tunnel The excavation consisted of an open cutting on 26,000 feet long and 9 feet in diameter has recently the American side 2500 feet long; a tunnel (iOOO been constructed, and two other older tunnels are feet long under the river, and an open cutting on also in use. one being 5 feet in diameter for GG62 the Canadian side 3100 feet long. Work was be- feet and BYs and 6 feet in diameter for 2580 feet, gun by means of two shore shafts in ISSS, but and the other being 7 feet in diameter and these were abandoned, and in 1889 work was com- 9200 feet long. One of the most notable water- meneed on the cuttings. These were completed so supply tunnels in the world is that which brings that shields were started on the tunnel proper in water to New York City, and which is known the same year. The shields used were 21% feet as the Croton Aqueduct. ( See Aqueduct. ) This outside diameter, and the cylindrical shell con- tunnel is 33 miles long and about 14 feet high si-ted of 1-inch steel plates. The cylinder was and 14 feet wide; it was built through rock. The stifl'ened by five diaphragms dividing it into Yyrnntj Aqueduct, 77 miles long, for bringing twelve cells. In front the shield had a cutting water to the city of Liverpool, England, has edae, and at the back it was prolonged 4 feet to three tunnels. The first and longest is the cover the lining of the tunnel. As the shield was Hirnant Tunnel, 2 miles 3 furlongs in length shoved forward a paste of cement and water was through solid rock. The second is the Cynynion forced out through holes left in the lining to fill Tunnel at mile 16. It is seven furlongs long; the space left between the lining and the elav. but the aqueduct only comes out of the tun- The excavation was done in front of the shield's, "l to pass in a siphon across a valley, entering which were then forced forward bv hvdraulic tile Llanforda Tunnel, which is one mile long, jacks, and the erection of the permanent cast- These tunnels are circular in section and 7 feet iron lining followed up. the ring being erected in- '". diameter. The third tunnel is that under the side the tail of the shield. There were 24 hv- Riyer Mersey, which is 805 feet long and lined draulie jacks at the back of each shield, each ^y'*'^ """" ""§** 10 f<^<^t '" diameter on the out- capable of exerting a power of 125 tons, but the ,t-. , . greatest total power used did not exceed 1800 , ^^ tlun recent years many important tunnels tons. The lining is 21 feet in outside diameter. ••'^" '"^" constructed to carry rapid transit rail- Each ring of linine is 18 inches long, measured on l^'^^^ ""'l'"'" "^^ f*^*^- ^9'"^ °J "^T' '"': Vu^ the line of the tunnel, and is made up of 13 seg- L°"' 9" t"""^' J'^T^ been deep tunnels but oth- , J „ 1 ,. „•„ T? 1 J- • i?„ ers. like those at Boston, Pans, and New lork, ments and a kev piece. Each segment weighs ,', ^ ^ i j, , ^ ii_ ,„-„ ■ 1 41 4. i 1 ■ I J. f i ■ "■ have been constructed for the most part bv open- 10.:)0 pounds, and the total weight of cast iron in , ., , . n i ii , i ii " J ., ,.' ■ . „- „„„ . m' -D 14.- T> li cut methods at a small depth below the surface, the lining is 2i.000 tons. Ine Baltimore Belt „, „., ,„., , j n i ■ ^ j T-. i 1 . £ • 1 4. i- I r J he I in/ and Soiitli London Knuirfiii, m London, Line tunnel is a tairlv representative example of , . looa i i j. i • lonn i ., . 1- 4.1 ■ i £4. 11, was begun in 1886 and completed in 1890. elec- railway tunneling through soft ground on land. 4. ■ -^ 'T ■ li- 4^ 1 1 V , ii t ,.,•„.,,.,■.„, - , . " ,, , tricitv being ultimatelv adopted as the means of anil the Snnit ( lair tunnel is an enuallv good ex- , ..' rf ■ o, -i ' 1 t n. -t <- 4-1 , , ., , ,. 1 4. ■ L traction. It is 3i miles long from the citv to the ample of railway tunneling under water by means g^^.^„ ^^ Stockw^ll, and is entirelv underground. of the shield method. g^i^,,^ ^,,,, ,.^,,j, p„,„i^ts of two 'lO feet inch Next to their use for railways, tunnels are more cast-iron lined tunnels substantiallv parallel to frequently built to conduct water than for any paph other, which converge into a single tunnel at other purpose, perhaps. A good example of rock the termini to permit the transfer of trains from tunneling for this purpose is afforded by the one line to the other. These tunnels were con- yirniarfi Tniinrl. buill to cany the water away strueted bv means of the shield svstem. The from the wheel pit of the Niagara Power Com- Waterloo and City RaiUray in London extends pany at Niagara Falls. N. Y. This tunnel is f,.nm the Waterloo station of the Southwestern 7i)00 feet long. 19 feet wide, and 21 feet high, and Railway to the Mansion House, a distance of runs through solid limestone rock. The Chicago 1 mile 4 furlongs and 150 yards. It consists of water-works tunnels, through which the city of two parallel circular tunnels 12 feet 1} inches Chicago draws its water supply from Lake Michi- interior diameter except at the curves, where the gan, constitute the most elaborate system of wa- dimension is increased to 12 feet inches. The ter-supply tunnels anywhere in the world. They tunnels were driven by the shield method, work comprise 21.97 miles of subaqueous tunnel and having been begun in 1894 and completed in
