Columbia University Libraries Digital Collections: The Real Estate Record

Real estate record and builders' guide: [v. 94, no. 2439: Articles]: December 12, 1914

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REAL ESTATE AND k^ BUILDERS mim. NEW YORK, DECEMBER 12, 1914 liiiliiliiiiiiliiiiitililili^^ I WILLIAM STREET SUBWAY A MIGHTY WORK | I The Underpinning of Giant Buildings Will Be the Prominent Feature—This I Will Cost $465 a Front Foot in Cases—Construction Methods Described H MORE publictiy has attended the various steps leading up to the construction of the subway through William Street than any other section. Almost every step has heen a hesitating one. William street is only forty feet wide, divided almost equally between sidewalks' and roadway. Seven thou¬ sand people pass one of its busy corners in a normal hour. Fearful that damage would be wrought to the buildings that line the street, many property owners were opposed for a time to the con¬ struction of the subway there, and lat¬ terly they entered a protest against the erection of trestles in front of stores and office buildiiigs to carry gas mains and other conduits while the road is un¬ der construction. The so-called "William street sub¬ way" will connect the Seventh avenue subway with the downtown business district 'of Manhat¬ tan, and with Brook¬ lyn. The route leaves the Seventh avenue line at West Broadway and Park place and runs through under the Post Office property to Beekman street and thence into Wil¬ liam. Then the route is down Wil¬ liam to Old Slip and under the East River to Clark street and Fulton street, Brooklyn, to make a junction w'ith the existing subway there. The value of the property along the William street sec¬ tion is estimated at $40,362,000. as the lower portion of the street is fianked by some of the largest and most expensive buildings in the city. Most of them are built on quicksand, but the Public Serv¬ ice Commission, on elsewhere the width will be twenty-nine feet. The gas mains will be carried in the gutters, except at street intersec¬ tions, when they must be elevated to trestles. The depth to subgrade will vary from twenty-five to thirty-one feet, through coarse sand, with some gravel, grading into fine sand which, below the water- line, becomes quicksand. At Pearl street the subgrade will be twenty feet l)elow mean high water, and sixteen feet at Maiden Lane. Floor and sidewalls will be built with brick and mastic waterproofing, as a matter of course. WILLIAM STREET, SOUTH FROM WALL. Showing nature of buildings to be underpinned—National City Bank on the left; the Bank of America, Atlantic Building, Land's Court and Corn Exchange Bank on the right. the advice of its engineers, takes the position that the buildings can be adequately shored up, and if necessary caissons will be sunk to secure their safety. The closeness of the excavation to the buildings, the unstable character of the soil, and the great property values at stake, are elements in one of the most difficult problem that the engineers have had to contend with. At stations the width of the excavation will be full forty feet between building lines, in or¬ der to provide for island platforms, and The great feat required of the engin¬ eers will be to keep the "swimming sand'* quiescent and confined, when it possesses a high bearing value, but when released it becomes dangerous in a high degree. Stations will be built to extend be¬ tween John and Ann street, and between Cedar and Wall. The entrances' will be, one on the cast side of Fulton street, for the first-named station, and for the other station there will be one entrance on the west side, at Pine street, and one on each side at Wall. Some anxiety has been expressed by owners and ten¬ ants over the location of the Pine street station. The possibility of a kiosk six feet wide occupyine a sidewalk nine feet eight inches wide has been appre¬ hended, but this is something that Avill never eventuate, the Record aiid Guide is officially assured. The precise loca¬ tion of the stairway will be determined after negotiations with the owners of adjacent property, and it is highly im¬ probable that it will be in a position where it will block traffic or injure pri¬ vate business. A very difficult and trying part of the construction work will be the under¬ pinning of buildings, it is almost unneces¬ sary to say. The proposed method will be decided on by the contractor, but must, by the terms' of the con¬ tract, receive the ap¬ proval of the com¬ mission, because primary responsibil¬ ity has, by the cotirts, been placed upon the city, for the first time in any contract for subway construction. At the same time the con¬ tractor has not been relieved of the usual full responsibility. The established practice for work of this character is to provide adequate temporary support and then build per¬ manent supports for the existing founda¬ tions from rock or hardpan beneath the piers or other points of load concentra¬ tion. Between the piers there will be continuous bulkhead walls (either of tight sheeting or solid concrete), to stop any tendency of the quicksand to flow. Similar walls will protect build¬ ings having adequate foundations, i f u n - impaired by the sub¬ way work. There are ten buildings of thirteen to twenty stories in height; twenty buildings ten to twelve stories high, and forty-five that have less than seven stories each, but ali with foundations below the sub¬ way subgrade. ^ Assistant Division Engineer John H- Madden, in a report which is printed in the Survey (the official bulletin of the P. S. Commission), says the construc¬ tion will probably be conducted from three working shafts, situated (1) at the southwest corner of Beekman street, (2) the northwest corner of Maiden