Norwich bulletin., 1917-08-13
STEEL DELAY HOLDING
 UP THAMES BRIDGE
Substructure Is Now Completed With Exception of Finishing Touches.

With the exception of the finishing touches on the masonry work on top of the piers, the substructure of the new Thames river bridge being built by the New York. New Haven & Hartford Railroad company across the Thames at New London is com pleted. The building of the steel su- perStructure has been delayed on ac- count of the war. The steel was con- tracted for a long time ago, but as is generally known, all the steel milla in the country are giving preference to government requirements and only such steel is being delivered at the present time is essential for the prosecution of the war
 Just when the New Haven will be able to obtain this steel is an uncer- tainty. It is hoped, however, that de- nveries will commence in the fall, in which case the bridge will be opened for operation in 1918. Ar interesting feature of the steel work and one that forcibly illustrates the high cost of railroad living, has to do with the estimated and actual cost figures of the steel. Three engineers-one New Haven engineer and the other engineering made separate estimates of the cost of the steel for this bridge. Their estimates varied by less than s4.0oO. But owing to the New Haven railroad will have to pay approximately s200,O more than any of these engineers estimated
 While the old bridge is some 3s feet it is considerably lighter. The old bridge is 1,425 feet long, while the new one will be 1887 feet The weight Of the old bridge is 2.400 tons, and structure was made of open hearth and Bessemer carbon steel of an eIas- tic strength of about 24,000 pounds per square inch. The new bridge will be of silicon steel. with an elas- tic strength of not less than 45,0o0 pounds per square inch. The old bridge is of the draw or swing span type, the span being operated by steam engines. The new bridge is of the vascule of lift span type, the span being operated by electric motors. The motors will be taken from three sources to insure against mishap and delay.
 In building the four piers for the substructure, open well dredging was the method employed for three of them, and the pneumatic caisson pro- cess for the other. The old bridge is placed on piles, but it was not prac- tical to use piles for the new bridge, as the soft river bottom loam or clay would not give adequate support to a pile cluster in a degree requisite for this bridge. The subsoil is mud or soft clay for 50 to 100 feet, water be- ing 20 to 50 feet deep. Below the mud is firm gravel to support the deep piers. The center piers adjacent to the channel, go down to a depth of l30 feet below water, in order to rest upon suitable foundation material. Above the tide level the piers and abUtments extend 25 feet high in an artistic design. They furnish the sup port for the steel pedestals of the bridge trusses, which are to carry the railway tracks. The extreme di- mensions of the foundations of the piers are Az feet by 9s feet It re- quired about 45 900 cubic yards of concrete to construct these piers.
 Over $1,0O0, 900 has already been ex- pended on the Thames river bridge. The new bridge will be a five span structure. with bascule type of lift The bascule type was chosen because of the saving in time required for opening and closing to permit vessels to pass up or down stream. The five spans from west to east will be 1855 feet, 330 feet, PIP feet, 330 feet and 330 feet. About 5,525 tons of steel will be used in the construction of the superStrGcture.