Show letting the tide do the heavy work N 9 4 X ak V IK an interesting and ami expensive piece of engineering work isander way in the construction of the die key bridge con seating the district of columbia with virginia it involves the removal of the huge steel span from under the con arete larch arch the steel span forming the temporary platform the operations are governed by the ebb rind and flow of the 1 tide a float floating frig platform carrying away the span as the water recedes the building of this huge bridge Is one of the biggest construction projects in the country and will be completed in about a year |