. Electric railway review . 10 feetRefuge bays or dei) about 10 inches by 2 feet by 6feet in dimension are placed at intervals along the side wallson alternate sides of the tracks. Eighty-pound standardT-rails, laid upon creosoted oak ties, constitute the trackstructure. The rails are double-spiked with screw spikesthroughout and the ties and rails are embedded in the concretefloor to within 2 inches of the toj) of the head of the rail. At the east approach to the tunnel the character of thesoil, which was found to be soft mud and peat, retpiired theplacing of 2 feet of concrete benea
. Electric railway review . 10 feetRefuge bays or dei) about 10 inches by 2 feet by 6feet in dimension are placed at intervals along the side wallson alternate sides of the tracks. Eighty-pound standardT-rails, laid upon creosoted oak ties, constitute the trackstructure. The rails are double-spiked with screw spikesthroughout and the ties and rails are embedded in the concretefloor to within 2 inches of the toj) of the head of the rail. At the east approach to the tunnel the character of thesoil, which was found to be soft mud and peat, retpiired theplacing of 2 feet of concrete beneath the ties, which werealso embedded in concrete in a similar manner to the trackof the main tunnel. The retaining walls in this approach restupon piling driven to a solid foundation. Construction. It was foimd desirable to construct the subway entirelyin an open trench, and in order to accomplish the work inthis manner it was necessary to do considerable material excavated was principally coarse sand contain-. Selby Hill Tunnel—Forms and Reinforcing Material for Crown of Arch. ing a small percentage of rock and gravel. Sheeting timbers4 by 6 inches, varying in length from 20 to 25 feet, weredriven in advance of the excavation. As the trench was deep-ened waling pieces 12 by 12 inches were placed longitudinallyacross the sheeting timbers on both sides of the trench andtransverse struts of rough timbers 12 to 14 inches in diameterwere placed between these waling pieces to act as bracesacross the trench. The waling timbers were spaced at inter-vals of 6 feet along the sheeting and the transverse strutswere i)laced at 6-foot intervals along the waling the trench was deeper than feet a second row ofsheeting was driven inside the first row. Along the south sideat the deepest part of the work was a stone retaining wallrising about 12 feet above the original street surface. Thisretaining wall was almost directly above the south side wallof the tunnel a
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectstreetr, bookyear1906
