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leV] 76 M t; T R 0 P () L IT A N W ATE I( D I S 'NU C T , I j ,I I but the 262-foot RockdaJe tunnel on North Figueroa Street in Los Angeles where the only support necessary was one timber set. No swelling nor heavy ground was encountered. Each pipe sec.tion was moved into the tunnels on spec.ial railroad dollies, jacked up to I permit removal of dollies and track, then set on line and grade and I welded to the previously placed section. The final operation was I the complete filling of the tunnel outside of the pipe with concrete. j The welded steel pipe was fabricated by Consolidated Steel , Corporation, Ltd., at its east Los Angeles plant from mild steel I plate ranging in thickness from % to 112 of an inch, generally in 30-foot lengths having a 2-inch belled end. The inside of this pipe was protected by a %-inch coating of cement mortar applied cen- "~"rO(Jd ~rQIi>t1' ;'Jv.-l,xt'J......r....,.,. c,~lv~l1,;~d ,ron or,I~~1 cornJq"f~d casrno}-m,n,mum I,~IC~M" 8 gauge'l , / U"ou/Jackd min 1~IC/(nnJJ~ . . "" t:"'" ~"';,(, .u__._n... -- ~!: . "."" _,.ron---- n__n I "~l I I...-Corruqoltd CO""'? ~,ng F,~riml{jpla,e ,'''~~Ie cradle LONGITUDINAL SECTION CROSS SECTION Ccmplet~d InJtal!a~iOfl Fig. 6. Jacked i1'1casement under structures trifugally to a shotblasted surface. The exterior was given a %-inch gunite coating reinforced with wire mesh and having an 'Is-inch coat of coal-tar enamel under the gnnite if it was to be laid where corrosive soils or electrolytic conditions existed. The coating was applied at the fabrication plant. Pipe laying followed closely the machine excavation and hand grad'ing of the trench, the sections being delivered to the line by semitrailer trucks and lowered into place by crane. All field joints were welded, tested, and coated. To prevent deflec.tion of the pipe in backfilling, steel plate bulkheads were installed about 1,000 feet apart, each section between bulkheads being filled with water and maintained under a pressure of not less than 20 pounds per square inch. Backfill was then placed and thoroughly sluiced. The street resurfacing was completed as soon as possible thereafter. Special structures were numerous, consisting of blow off valves at low points, shutoff valves at strategic locations, pressure-regu- , ~ i 1 I I I I ~