WORLD'S GREATEST ARCH

Dominion, Volume 9, Issue 2664, 8 January 1916, Page 15

WORLD'S GREATEST ARCH

The largest steel arch in the world, and also the heaviest steel bridge over built, is that which carries the Pennsylvania railway tracks over the East River at Hell Gate, New York. It lias a span of 1000 ft. between the abutments, and 80,000 tons of stoel have been used in its construction. The immenso bridge has been practically completed. Some complex problems were involved in its construction. The main towers, 260 ft. high, were intended to rest on solid rook, but it was found that a fissure on one side ran rigjit across the site of the tower. This was at too great a depth to be reached by pneumatic work, and the bold expedi-, ent of bridging this gap with a concrete arch was decided upon as a way out of the difficulty. The tower was then erected without any mishap on the made foundation. Tho operation of closing the arch was most interesting. Th a final-sections of the bottom chord, each weighing 80 tons, were floated 011 barges directly underneath the gap, and then, means of a travelling crano at either end of the arch, these were raised and bolted into position, thereby making tho structure sclf-sup-portrng, ' 1