▁for ▁the ▁first ▁time . ▁Work ers ▁riv et ed ▁both ▁top ▁and ▁bottom ▁sections ▁of ▁the ▁arch ▁together , ▁and ▁the ▁arch ▁became ▁self - support ing , ▁allowing ▁the ▁support ▁c ables ▁to ▁be ▁removed . ▁On ▁ 2 0 ▁August ▁ 1 9 3 0 ▁the ▁joining ▁of ▁the ▁arch es ▁was ▁celebrated ▁by ▁flying ▁the ▁flags ▁of ▁Australia ▁and ▁the ▁United ▁Kingdom ▁from ▁the ▁j ib s ▁of ▁the ▁cre eper ▁c ran es . ▁ ▁Once ▁the ▁arch ▁was ▁completed , ▁the ▁cre eper ▁c ran es ▁were ▁then ▁worked ▁back ▁down ▁the ▁arch es , ▁allowing ▁the ▁road way ▁and ▁other ▁parts ▁of ▁the ▁bridge ▁to ▁be ▁constructed ▁from ▁the ▁centre ▁out . ▁The ▁vertical ▁h angers ▁were ▁attached ▁to ▁the ▁arch , ▁and ▁these ▁were ▁then ▁joined ▁with ▁horizontal ▁cross be ams . ▁The ▁deck ▁for ▁the ▁road way ▁and ▁railway ▁were ▁built ▁on ▁top ▁of ▁the ▁cross be ams , ▁with ▁the ▁deck ▁itself ▁being ▁completed ▁by ▁June ▁ 1 9 3 1 , ▁and ▁the ▁cre eper ▁c ran es ▁were ▁dis m ant led . ▁Rails ▁for ▁trains ▁and ▁tr ams ▁were ▁laid , ▁and ▁road ▁was ▁sur fac ed ▁using ▁concrete ▁to pped ▁with ▁as ph alt . ▁Power ▁and ▁tele phone ▁lines , ▁and ▁water , ▁gas , ▁and ▁d rain age ▁pip es ▁were ▁also ▁all ▁added ▁to ▁the ▁bridge ▁in ▁ 1 9 3 1 . ▁ ▁The ▁p yl ons ▁were ▁built ▁at op ▁the ▁ab ut ment