diff options
| author | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:54:44 -0700 |
|---|---|---|
| committer | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:54:44 -0700 |
| commit | dd9452b137222c6fa1f2275f245057022238f968 (patch) | |
| tree | a32b561c28add62fbb8399c3bfdbe8147bdc5a4d /19037.txt | |
Diffstat (limited to '19037.txt')
| -rw-r--r-- | 19037.txt | 1688 |
1 files changed, 1688 insertions, 0 deletions
diff --git a/19037.txt b/19037.txt new file mode 100644 index 0000000..04e007e --- /dev/null +++ b/19037.txt @@ -0,0 +1,1688 @@ +The Project Gutenberg EBook of Transactions of the American Society of +Civil Engineers, Vol. LXVIII, Sept. 1910, by James H. Brace and Francis Mason + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Transactions of the American Society of Civil Engineers, Vol. LXVIII, Sept. 1910 + The New York Tunnel Extension of the Pennsylvania Railroad. + The Cross-Town Tunnels. Paper No. 1158 + +Author: James H. Brace and Francis Mason + +Release Date: August 13, 2006 [EBook #19037] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK TRANSACTIONS OF THE AMERICAN *** + + + + +Produced by Juliet Sutherland, Jacqueline Jeremy and the +Online Distributed Proofreading Team at http://www.pgdp.net + + + + + + + + + +AMERICAN SOCIETY OF CIVIL ENGINEERS + +INSTITUTED 1852 + + +TRANSACTIONS + +Paper No. 1158 + + +THE NEW YORK TUNNEL EXTENSION OF THE +PENNSYLVANIA RAILROAD. +THE CROSS-TOWN TUNNELS.[A] + +BY JAMES H. BRACE AND FRANCIS MASON, MEMBERS, AM. SOC. C. E. + + + + +In this paper, it is proposed to describe the construction of the +tunnels extending eastward from the easterly extension of the Terminal +Station to the permanent shafts east of First Avenue. + +They were located under 32d and 33d Streets from the station to Second +Avenue, and thence, curving to the left, passed under private property +and First Avenue to the shafts, as described in a preceding paper. +Typical cross-sections of the tunnels are shown on Plate XII.[B] + +On May 29th, 1905, a contract was entered into with the United +Engineering and Contracting Company for the performance of this work. +This contract provided that work on each pair of tunnels should be +carried on from two shafts. The first, here referred to as the First +Avenue Shafts, were located just east of that avenue and directly over +the line of the tunnels; the other two, called the Intermediate Shafts, +were located on private property to the north of each pair of tunnels in +the blocks between Fourth and Madison Avenues. It was originally +intended to do all the work of construction from these four shafts. +Workings were started both east and west from the Intermediate Shafts, +and those to the west were to be continued to the Terminal Station. +After the change of plans, described in a previous paper, it was decided +to sink a third shaft on each line. These were known as the West Shafts, +and were located between Sixth and Seventh Avenues. Finally, it was +found necessary to build a portion of the tunnels on each line west of +Sixth Avenue in open cut. The locations of the shafts are shown on Plate +XIV.[C] + +The First Avenue shafts were built by S. Pearson and Son, Inc., for the +joint use of the two contractors, as described in the paper on the +tunnels under the East River. While the shafts were being sunk, the +full-sized tunnels were excavated westward by the contractor for the +river tunnels for a distance of 50 ft., and top headings for 50 ft. +farther. By this means, injury to the caissons and to the contractor's +plant in the shafts by the subsequent work in the Cross-Town Tunnels was +avoided. The west half of the shaft was for the exclusive use of the +contractor for the Cross-Town Tunnels. + + +CONTRACTOR'S PLANT. + +The method of handling the work adopted by the contractor was, broadly +speaking, as follows: Excavation was usually carried on by modifications +of the top-heading and bench method, the bench being carried as close to +the face as possible in order to allow the muck from the heading to be +blasted over the bench into the full section. The spoil was loaded into +3-yd. buckets (designed by the contractor and hereinafter described), by +steam shovels operated by compressed air, and hauled to the shafts by +electric locomotives. Electrically-operated telphers, suspended from a +timber trestle, hoisted the buckets, and, traveling on a mono-rail +track, deposited them on wagons for transportation to the dock. Arriving +at the dock, the buckets were lifted by electrically-operated stiff-leg +derricks and their contents deposited on scows for final disposal. The +spoil was thus transported from the heading to the scow without breaking +bulk. + +When concreting was in progress, the spoil buckets were returned to the +shafts loaded with sand and stone. The concrete materials were deposited +in storage bins placed in the shafts, from which they were fed to the +mixers located at the foot of the shaft about on a level with the crown +of the tunnels. The concrete was transported to the forms in side-dump, +steel, concrete cars, hauled by the electric locomotives. + +Electrical power was adopted largely on account of the restricted area +at the shaft sites, where a steam plant would have occupied considerable +space of great value for other purposes. The installation of a steam +plant at the Intermediate Shafts, which were located in a high-class +residential district, would have been highly objectionable to the +neighboring property owners, on account of the attendant noise, smoke, +and dirt, and, in addition, the cost of the transportation of fuel would +have been a serious burden. Except for the forges and, toward the last, +the steam locomotives, not a pound of coal was burned on the work. The +use of the bucket and telpher also eliminated most of the objectionable +noise incident to the transfer of spoil from tunnel cars to ordinary +wagons at the shaft sites. Power plants were installed at the North +Shaft near First Avenue and at the rear of the 33d Street Intermediate +Shaft. + +_First Avenue Plant._--Fig. 1, Plate LVIII, is a general view of the +First Avenue plant. The power-house at the corner of 34th Street and +First Avenue supplied compressed air for operating drills, shovels, +pumps, and hoists in the tunnels driven from the river shafts, and in it +three Laidlaw-Dunn-Gordon compressors were installed. The largest was a +32 by 20 by 30-in., two-stage, cross-compound, direct-connected to a +Fort Wayne 480 h.p., 230-volt, direct-current, constant-speed motor run +at 100 rev. per min. This compressor was rated at 2,870 cu. ft. of free +air per minute at a pressure of 100 lb. It was governed by throttling +the suction, the governor being controlled by the pressure in the air +receiver and the motor running continuously at a constant speed. The two +others were of similar type, one was 22-1/2 by 14 by 18-in., rated at +1,250 cu. ft. of free air at a pressure of 100 lb., the other was 16 by +10 by 18-in., rated at 630 cu. ft. They were fitted with 9-ft. +fly-wheels, and were driven at 150 rev. per min. by 105-h.p., General +Electric, 220-volt, compound-wound, direct-current motors running at 655 +rev. per min. The larger of these two compressors was driven by two of +the motors belted in tandem, and the smaller was belt-connected to a +third motor. The compressors were water-jacketed and had small +inter-coolers, the water supply for which was itself cooled in a Wheeler +Condenser and Engineering Company's water-cooling tower. The pump and +the blower operating it were electrically driven. + +The telphers, used for hoisting muck from the tunnels and for lowering +supplies, were each hung from single rails on a timber trestle, about +40 ft. high, spanning and connecting the two shafts. One machine was +provided for each shaft, and where their tracks crossed 33d Street they +were separated sufficiently to permit the machines to pass each other. +At this point, and covering the street, a large platform was provided, +on which the trucks were loaded and unloaded (Fig. 2, Plate LVIII), and +from which they descended by an incline on First Avenue leading south to +32d Street. The platform also covered practically all the yard at the +South Shaft and materially increased the available working area. The +telphers were built by the Dodge Cold Storage Company, and were operated +by a 75-h.p. General Electric motor for hoisting and a 15-h.p. Northern +Electric Company motor for propulsion. Their rated lifting capacity was +10,000 lb. at a speed of 200 ft. per min. + +The carpenter shop and machine-shop, both of which served the entire +work, were conveniently located in small buildings on the loading +platform. In the former the saws were each run independently by small +electric motors suspended under the platform. The heavy forms and form +carriages used in lining the tunnels with concrete were fabricated and +stored on the platform outside. The machine-shop lathes, etc., were all +belted to one shaft driven by an 8-h.p. General Electric motor. Above +the machine-shop was a locker-room and below it on the street level was +the main blacksmith shop for the work. Subsidiary blacksmith shops were +located at each of the other shafts. The storeroom and additional +locker-rooms were located above the power-plant in the North Shaft yard, +and isolated from the other structures was a small oil-house. Additional +storage space was provided by the contractor on 32d Street just west of +First Avenue by renting three old buildings and the yards in the rear of +them and of the Railroad Company's cement warehouse adjacent. Here +electric conduits, pipe, castings, and other heavy and bulky supplies +were stored. + +During excavation the headings were supplied with forced ventilation +through 12-in. and 14-in. No. 16, spiral-riveted, asphalted pressure +pipes, canvas extensions being used beyond the ends of the pipes. A No. +4 American Blower, located at the top of each shaft and driven by a +15-h.p. General Electric motor, supplied the air. + +[Illustration: PLATE LVIII, FIG. 1.--VIEW OF FIRST AVENUE PLANT.] + +[Illustration: PLATE LVIII, FIG. 2.--TELPHER STRUCTURE AND LOADING +PLATFORM, FIRST AVENUE SHAFT.] + +[Illustration: PLATE LVIII, FIG. 3.--HEADWORKS AT 33D STREET: +INTERMEDIATE SHAFT.] + +[Illustration: PLATE LVIII, FIG. 4.--LOADING SPOIL ON BARGES, 35TH +STREET PIER.] + +A concrete-mixing plant was placed in each shaft, the mixer being +located high enough to discharge into cars at about the level of the +springing line of the arch. Above the mixers were the measuring +hoppers set in the floor of a platform which was large enough to carry +half a day's supply of cement. At the South Shaft the cement was +delivered to this floor from the loading platform through a spiral steel +chute; at the North Shaft it was lowered in buckets by the telpher. The +sand and stone were drawn into the hoppers through short chutes from the +base of the storage bins which occupied the remaining height of the +shaft--about 50 ft. At the South Shaft the bins were of concrete and +steel, about 6 by 12 ft. in section, and attached to the central wall of +the caisson. Sand and stone were delivered into them from dump-wagons on +the loading platform. At the North Shaft steel-plate bins were used, and +were supplied with material by the buckets handled by the telpher. The +mixers were No. 5 Smith, belt-connected to 25-h.p. motors, and about 0.8 +cu. yd. of concrete was mixed at a batch. The concrete cars were steel +side-dumpers of the Wiener or Koppel type. + +In order to be able to continue concreting during the winter, when +neither sand nor stone could be obtained by water, practically all the +space under the loading platforms in the South Shaft yards not occupied +by the blacksmith shop was filled with these materials, which were +placed in storage in the late fall. + +_Intermediate-Shaft Plant._--The air-compressing plant was located at +the rear of the 33d Street Intermediate Shaft, and supplied air for +driving the tunnels east and west from the Intermediate Shafts on both +32d and 33d Streets. Two compressors, the same as the large +Laidlaw-Dunn-Gordon machine at First Avenue, were installed here, with a +similar water-cooling tower. + +Both shafts were on private property, owned by the Railroad Company, on +the north side of the streets, and each was equipped with two telphers +supported on timber trestles, similar to those at First Avenue. Here, +however, the buckets were placed on wagons standing at the curb, as +shown by Fig. 3, Plate LVIII. + +Blowers for ventilation were installed at each shaft, as at First +Avenue, and, after the excavation had proceeded some distance, small +blacksmith shops, for sharpening drill steel and making minor repairs, +were located in the tunnels near the shafts. + +The concrete plant in each shaft was similar in arrangement to those at +First Avenue, but the storage bins had wooden walls made of 2 by 4-in. +and 2 by 6-in. scantling nailed flat on each other. + +The contractor's office on 33d Street backed up against the 32d Street +shaft site, and the basement was used as a storeroom for supplies for +both shafts. + +After the decision to do part of the work between Sixth and Seventh +Avenues in open cut, an 8-in. air main was laid in 33d Street to the +West Shafts, and air was supplied from the Intermediate Shaft for work +on both streets in that neighborhood. + +_West-Shaft Plant._--West of Sixth Avenue, between 32d and 33d Streets +and adjacent to the open-cut sections, the Railroad Company obtained +from the Hudson and Manhattan Railroad Company the use of a large area +from which the buildings had recently been removed, and gave the use of +it to the contractor. This was of great value in prosecuting the west +end of the work. The two West Shafts were located in the streets and +were supplied with short timber trestles similar to those at the +Intermediate Shafts. One telpher was taken from each of the Intermediate +Shafts to operate at each of the West Shafts. In addition, a number of +stiff-leg derricks were set up along the open-cut section, and were +operated by Lidgerwood or Lambert air hoisting engines, or by electric +motors, as circumstances dictated. A 15-ton Bay City locomotive crane +was also used along part of the open-cut work on 32d Street. + +Several concrete plants were installed at points along the open-cut +section, and were moved from place to place, the same general +arrangement being adopted as at the plants already described. No. 3 and +No. 4 Ransome mixers were used, and were generally set up at about the +level of the top of the arch. The sand and stone storage bins were made +of scantlings spiked together, and were necessarily rather shallow on +account of the proximity of the tunnels to the street surface. + +_Thirty-fifth Street Pier._--For the receipt and disposal of materials +at the 35th Street pier, four stiff-leg derricks, operated by electric +hoisting engines, were installed. Two were used in lifting the muck +buckets from the wagons and dumping their contents on the scows for +final disposal (Fig. 4, Plate LVIII); and the other two were fitted with +clam-shell buckets for unloading sand and broken stone from barges and +depositing the materials in large hoppers, from which they were drawn +into wagons for transportation to the various concrete plants. A large +part of the cement (all of which was supplied by the Railroad Company) +was also unloaded at the 35th Street pier and hauled directly to the +work, the surplus being stored temporarily in the Company's cement +warehouses on 32d, 33d and 35th Streets, near First Avenue, from which +it was drawn as required. On the dock was located the main powder +magazine, a small concrete structure. Considerable use was also made of +neighboring piers for unloading electric conduits, lumber, steel, etc. + +[Illustration: FIG. 1. SPECIAL STEEL BUCKET + PLAN OF BUCKET + END VIEW + SIDE VIEW OF BUCKET + SECTION AT A-A] + +_Tunnel Plant._--The spoil buckets, designed by D. L. Hough and George +Perrine, Members, Am. Soc. C. E., were a novel feature of the work. +These buckets are shown in detail in Fig. 1 and various photographs. +They were of 3 cu. yd. capacity and were split longitudinally, the two +halves being pinned at the apices of the ends. For lifting, they were +suspended from eyes at that point, and, when dumping, trip ropes were +hooked into eyes at the bottom of each side; lifting the trip ropes or +lowering the hoisting rope split the bucket, as shown in Fig. 4, Plate +LVIII, and dumped the contents. They were transported in the tunnel on +flat cars, and in the street on wagons, both cars and wagons being +provided with cradles shaped to receive the bottom of the bucket. + +In the tunnels the loading was done with air-operated steam shovels, +four (Model 20) Marion shovels being used at various points of the work. +In Fig. 1, Plate LIX, one of these is shown loading the bucket. The cars +were hauled by General Electric, standard, 10-ton, mine locomotives, the +current for which was taken at 220 volts from a pair of No. 00 copper +trolley wires suspended from the roof of the tunnel. The collector was a +small four-wheeled buggy riding on the wires and connected to the +locomotive by several hundred feet of cable wound on a reel for use +beyond the end of the trolley wire. Two 8-1/2-ton, Davenport, steam +locomotives were also used in 32d Street, toward the end of the work, +after the headings had been holed through and the tunnels would quickly +clear themselves of gas and smoke. The steam shovels were supplemented +by two Browning, 15-ton, locomotive cranes, which handled the spoil in +places where timbering interfered with the operation of the shovels. All +tracks were of 3-ft. gauge throughout and laid with 40-lb. rails. + +Practically all the heavy drilling was done with Ingersoll drills (Model +E 52), the trimming being largely done with jap and baby drills. A large +number of pumps were used at various points on the work, and practically +all were of Cameron make, the largest ones at the shaft being 10 by 5 by +13-in. The grout machines were of the vertical-cylinder, air-stirring +type. + + +SHAFT SINKING. + +The sinking of the Intermediate Shafts was the first work undertaken by +the contractor. + +The 33d Street Shaft was 34.5 ft. long, 21 ft. wide, and 83 ft. deep. +The rock surface averaged 5 ft. below the ground surface. Sinking was +started on July 10th, 1905, and was completed on October 3d, 1905, the +rock being hard and dry. The average daily rate was 0.73 ft. and an +average of 17.1 cu. yd. were excavated per day, with two shifts of 8 hr. +each. The first shift started at 6 A. M. and the second at 2.30 P. M., +ending at 11 P. M. These hours were adopted in order to avoid undue +disturbance during the night. + +[Illustration: PLATE LIX, FIG. 1.--AIR-OPERATED STEAM SHOVEL USED IN +TUNNEL.] + +[Illustration: PLATE LIX, FIG. 2.--TIMBERING IN TOP HEADINGS ABOVE +I-BEAMS.] + +[Illustration: PLATE LIX, FIG. 3.--FIRST SECTION OF CONCRETE LINING AT +FIFTH AVENUE.] + +[Illustration: PLATE LIX, FIG. 4.--TIMBERING AND RUBBLE MASONRY OVER +I-BEAMS.] + +Before blasting the first lift of rock, channel cuts 5 or 6 ft. deep +were made along the sides of the shaft, in order to avoid damage to the +walls of neighboring buildings. Timbering was required for a depth of +only 10 ft. below the surface of the ground. + +A drift, 30.6 ft. long, 17 ft. wide, and 27 ft. high, connected the +south end of the shaft with the tunnels. The drift was excavated in +three stages, a top heading and a bench in two lifts. While blasting the +cut in the top heading, there was enough concussion to break glass in +the neighboring buildings. The use of a radialax machine reduced the +concussion somewhat, but it was very quickly abandoned on account of the +length of time required for the drilling. + +The construction of the 32d Street Shaft was quite similar to the one on +33d Street. It was 31.5 ft. long, 20.5 ft. wide, and 71 ft. deep. The +depth of earth excavation averaged 19.5 ft. The rock in this shaft was +seamy and not quite as hard or dry as that in 33d Street, and timbering +was required for practically the full depth to the crown of the drift. +Sinking was started on May 15th, 1905, and was completed on October +26th, 1905. The daily average rate was 0.30 ft. in earth and 0.52 ft. in +rock. The drift was excavated in much the same manner as the one in 33d +Street, but the rock being softer the radialax machine was not used. + + +TUNNEL EXCAVATION. + +During the early part of the work, the contractor devoted his entire +attention to the work of excavation. Nearly all the excavation east of +Fifth Avenue was done before any of the lining was placed. At a number +of points west of Fifth Avenue and at a few points to the east the +nature of the rock was such that the two operations had to be done +simultaneously. + +_Single-Tunnel Method._--For an average distance of 350 ft. west from +the First Avenue Shafts there were four single tunnels. The rock was +sound and comparatively dry. A top heading of the full size of the +tunnel and about 8 ft. high was first driven. It was drilled by four +drills mounted on two columns, and was blasted in the ordinary way. The +bench was about 13 ft. high. Tripod drills, standing on the bench, +drilled the usual holes, but, owing to the lack of head-room, steels +long enough to reach the bottom of the bench could not be used. Tripod +drills were set as low as possible at the foot of the bench and drilled +lifting holes. These holes were inclined downward from 10 deg. to 15 deg. to the +horizontal, and were spaced to converge at the location of the drainage +ditches. The heading was usually driven from 10 to 20 ft. in advance of +the bench. At this distance a large part of the muck from the heading +was shot backward over the bench. In the single tunnels the muck was +loaded by hand. + +_Twin-Tunnel Methods._--From the end of the single-track tunnel westward +to Fifth Avenue on 33d Street, and to Madison Avenue on 32d Street, with +some exceptions, each pair of tunnels was excavated for the entire width +at one operation. Three different methods of work were extensively used. +They were the double-heading method, the center-heading method, and the +full-sized-heading method, and these differed only in the manner of +drilling and blasting. The bench was usually within 10 or 15 ft. of the +face of the heading, and was drilled and fired in the same way as in the +single tunnels. After the installation of the permanent plant, most of +the muck was handled by steam shovels. + +In the double-heading method, shown on Plate LVII, the top headings for +each tunnel of the pair were driven separately, leaving a short rock +core-wall between them. The headings were drilled from columns in the +manner described for the single tunnels. The temporary rock dividing +wall between the headings was drilled by a tripod drill on the bench of +one of the headings, and was fired with the bench. + +In the center-heading method, also shown on Plate LVII, only one heading +was driven. It was rectangular in shape, about 8 ft. high and 14 ft. +wide. It was located on the center line between the tunnels. In general, +the face was from 6 to 12 ft., or the length of one or two rounds, in +advance of the remainder of the face at the top. The center heading was +drilled by four drills mounted on two columns. By turning these drills +to the side, they were used for holes at right angles to the line of the +tunnels, by which the remainder of the face of the heading was blasted. +By turning the drills downward, the bench holes under the center heading +were also drilled. The center heading explored the rock in advance of +the full-width heading, and gave a good idea as to the care needed in +firing. + +For the full-width-heading method, Fig. 2, ten drills were mounted on +five columns set abreast across the face. Holes were drilled to form a +cut near the center line between the tunnels. The remainder of the holes +were located so that they would draw into the cut. The bench was +frequently drilled from the same set-up of columns by turning the +drills downward. In sound rock this method proved to be the most rapid +of any. + +Practically all trimming was left until immediately before the +concreting. It was then taken up as a separate operation, but proved to +be costly and tedious, and a hindrance to the placing of the lining. + +_Materials Encountered._--All the rock encountered was the familiar +Hudson schist, but it varied widely in its mineral constituents and in +its physical characteristics. In many places where the rock surface was +penetrated, a fine sand was found that was probably quicksand. The +material above the rock in the open-cut sections was mostly sand. + +[Illustration: FIG. 2. METHOD OF EXCAVATING WITH FULL-WIDTH HEADING +CROSS-TOWN TUNNELS, MANHATTAN + SIDE ELEVATION + FRONT ELEVATION + PLAN SHOWING POSITION OF COLUMNS FOR DRILLING FACE] + +The concurrence of the watercourse, shown on General Viele's map of +Manhattan Island (Plate IX[D]), with the points where difficulties in +the construction of the tunnels were encountered has been noted in a +previous paper. + +In all cases where the course of this ancient stream was crossed (except +at its final intersection of 33d Street), the rock was found to be very +soft and disintegrated, a large quantity of water was encountered, and +heavy timbering was required. The construction at these localities will +be taken up later. In addition, disintegrated rock, but of a less +troublesome character, was invariably met under the depressions in the +rock surface developed by the borings from the streets and test holes +from the tunnels. Many of these places required timbering, and no +timbering was elsewhere necessary except at the portals. These +coincident conditions were especially marked in 32d Street, which for a +long distance closely adjoins the course of the former creek. + +_Disposal of Spoil._--The materials excavated from the tunnels were +dumped at the 35th Street pier on barges furnished by the Railroad +Company under another contract, and were towed to points near the +Bayonne peninsula where the spoil was used principally in the +construction of the Greenville Freight Yards and the line across the +Hackensack Meadows to the tunnels. Details of this work will be given in +a subsequent paper. After December, 1907, when the excavation was about +85% completed, the contractor furnished the barges and effected the +complete disposal of the spoil. + +_Difficulties of Excavation._--As stated in a previous paper, the +excavation of the Twin Tunnel in 33d Street was continued westward to +the west line of Fifth Avenue on the original grade. At that point the +contractor started three drifts in the three-track section. The relation +of the drifts to each other and to the cross-section are shown by Fig. 3. +The center heading was driven a little in advance of those on the +sides. At a distance of 65 ft. west of Fifth Avenue the rock surface was +broken through in the top of the heading, and a very fine sand was +encountered. For some distance east of this point the rock was badly +disintegrated, and the heading required timbering. Through the soft +material, tight lagging was placed on the sides and roof of the heading, +and the face was protected by breast boards. There was a moderate flow +of water through the cracks, and, in spite of every effort, some of the +fine sand was constantly carried into the heading. + +In one or two instances considerable ground was lost at the face. On the +evening of December 14th, 1906, as a heavy coal wagon was passing along +33d Street above the heading, the rear wheels dropped through the +asphalt pavement. An examination disclosed a cavity under the pavement +about 14 ft. long, 12 ft. wide and 14 ft. deep. Evidently, the fine sand +had gradually settled into the voids caused by the loss of material at +the face, and the settlement broke the brick sewer over the heading. The +sewer was temporarily repaired, and the hole in the street was filled +before morning. A tight bulkhead was built across the heading, and work +was abandoned at that point. The north drift was advanced to a point +108 ft. west of Fifth Avenue where sand was also encountered and a +considerable run occurred. After that time all work on the three-track +section was discontinued. + +The Company then took up the consideration of changes in plan. To +determine the difficulties of driving a Twin Tunnel at a lower +elevation, an exploration drift, 8 ft. high and 12 ft. wide, was driven +on the center line of the street as a top heading on the proposed new +grade. Test holes were drilled above this heading and to the sides. The +results indicated that there was sufficient rock cover of fair quality +to enable the Twin Tunnel to be driven without great risk. The new plan +(continuing the Twin Tunnel westward at a lower grade) was adopted in +March, 1907, and work was immediately resumed at Fifth Avenue. + +The relation between the cross-sections under the old and new plans at +that point is shown by Fig. 3. Before the new section was excavated it +was necessary to support the timber work in the old headings. The plan +adopted is also shown by Fig. 3. The rock was excavated under the center +heading, as shown in cross-section, for a length of about 3 ft. A girder +composed of two 18-in. I-beams was then put in position over each line +and supported on the sides by posts. The ends at the center lines +between the tunnels were supported on short posts bearing on the rock +bench. The support of the timbering in the headings was then transferred +to the girders by additional posts. Blocking was also inserted between +the tops of the beams and the rock walls between the headings. Fig. 2, +Plate LIX, gives a good idea of the timber work in the top headings +above the I-beams. When the roof had been made secure, the removal of +the bench was begun. As the work advanced it was necessary to replace +the short posts at the center of the tunnel by others of full height, +and there was considerable settlement in the I-beams during this +operation. When the bench had been removed to a point 61 ft. west of +Fifth Avenue, settlement was detected in the street surface above. Bench +excavation was suspended and a section of the permanent lining, 35 ft. +long, was placed. The space between the lining and the beams and between +the beams and the roof was filled with rubble masonry. Grout pipes were +built into the masonry and later all voids were filled with grout. Fig. +3, Plate LIX, shows the first section of the concrete lining completed +and part of the rubble in place; and Fig. 4, Plate LIX, shows details of +the work above the tunnels. A second section of bench was next removed +and more lining was placed. Work was continued in this way until all the +roof at the old three-track headings had been secured. In this portion +of the work the posts were embedded in the concrete. + +Between Fifth and Sixth Avenues there were two more sections of bad rock +where it was necessary to support the roof with steel beams. At these +latter points there were no complications with the excavation for the +Three-Track Tunnel, and the work was much simpler. To avoid leaving the +center posts in the permanent work, two rows of temporary posts were +placed, as shown by Fig. 1, Plate LX, the center wall and skewback were +built, and the posts were removed, as shown by Fig. 2, Plate LX, before +placing the remainder of the lining. + +In 32d Street the normal progress of the excavation was frequently +interrupted by encountering soft and unsound rock. In the excavation +between the East River and the Intermediate Shafts it was possible to +overcome these conditions by temporarily narrowing the excavation on one +side and supporting the roof on 16 by 16-in. transverse timbers caught +in niches in the rock at the sides, leaving sufficient room for the +steam shovel to work through. In order to save time, the height of the +excavation was not increased before placing these timbers, so that, +previous to the concreting, they all required to be raised to clear the +masonry lining and were then supported on posts on the center line +between the tunnels. This permitted the remainder of the excavation to +be made, and such additional timbering as was required was placed. At +most of these sections a brick arch and water-proofing were used, on +account of the presence of water. In certain places the center line +posts were buried in the core-wall, and, in order to permit the placing +of the water-proofing, were then cut off one by one flush with its top +as the load was transferred to the completed masonry. In other cases the +load was transferred to posts clear of the masonry and the center line +posts were entirely removed. Under such conditions the normal concrete +methods, to be described later, could not be used, and special forms +were substituted. + +[Illustration: FIG. 3. CONSTRUCTION OF TWIN TUNNELS, THROUGH EXCAVATION +STARTED FOR THREE-TRACK TUNNEL IN 33D STREET NEAR 5TH AVENUE] + +In this section of the work the most serious difficulties were +encountered near Fourth Avenue a short distance east of the Intermediate +Shaft, and beneath the site of the old pond shown on General Viele's +map. The rock cover was known from the boring to be very thin, and the +presence of the subway overhead caused some anxiety. The excavation was +at first taken out to practically full width and timbered, but the rock +became so treacherous that the heading was narrowed to a width +sufficient for one tunnel only. With this span the rock in the roof held +without timbering. As the masonry lining approached, sufficient trimming +was done to permit the placing of the core-wall and one arch. Above the +completed core-wall and brick arch the voids were filled solid with +rubble masonry to give an unyielding support to the roof. The excavation +of the remaining width of tunnel was then undertaken. Near the west side +of Fourth Avenue, the excavation broke out of rock at the top, and fine +sand and gravel with a large quantity of water were encountered. The +work of excavation was arduous, and proceeded very slowly, on account of +the care with which it was executed. Only a small amount of sand entered +the tunnel, but the lining was placed as soon as the excavation was +completed. Rubble masonry packing and grout ejected through pipes built +into the arch were used to fill the voids above the roof. As a further +precaution against the settlement of the subway, 2-in. pipes were washed +down from the street above the point where soft ground was exposed in +the roof of the tunnel, and through them grout was forced into the +ground at various depths. Careful levels show that no settlement of the +subway has taken place. + +West of the Intermediate Shaft the tunnel was excavated for full width +until bad rock was encountered about 60 ft. west of Madison Avenue. (See +General Viele's map, Plate IX.) Timbering was used for a short distance, +and then the heading and bench were narrowed to 18 ft., and steam-shovel +excavation was abandoned. As the heading advanced the rock grew steadily +softer, the difficult conditions in this locality culminating when a +slushy disintegrated feldspar was met, requiring poling and breasting. +Thereafter the rock improved markedly, but near the east side of Fifth +Avenue its thickness above the roof was found to be only 1-1/2 ft., +and the advance was stopped, pending a decision as to a change of plan. + +[Illustration: PLATE LX, FIG. 1.--DOUBLE ROW OF POSTS UNDER I-BEAMS, +SUPPORTING ROOF IN BAD ROCK SECTION.] + +[Illustration: PLATE LX, FIG. 2.--CENTER WALL AND SKEWBACK UNDER I-BEAMS, +AFTER REMOVAL OF DOUBLE ROW OF POSTS.] + +[Illustration: PLATE LX, FIG. 3.--TIMBERING IN FULL-WIDTH HEADING OF +THREE-TRACK TUNNEL.] + +[Illustration: PLATE LX, FIG. 4.--UNDERPINNING WALLS IN OPEN-CUT +SECTION.] + +After some delay, an exploration drift, similar to the one already +described, was driven through to Sixth Avenue, and a change in plan was +made, substantially the same as for the 33d Street tunnels. Enlargement +to full size was at once started, but, for 400 ft. the rock was very +soft and poor, and required extremely careful handling. The exploration +drift was widened out to the full Twin-Tunnel width, and I-beams were +placed and supported, in much the same manner as in 33d Street. The rock +was so soft that it was frequently necessary to drive poling boards +ahead as the face was mined out with picks and shovels. The load was +very heavy, and the work the most difficult encountered in the tunnels. + +After this stage of the enlargement was reached, the excavation of the +bench and the placing of the lining proceeded alternately, with the +I-beams temporarily supported on long posts while the concrete core-wall +was being built. Considerable settlement took place while shifting the +posts, and eventually showed on the street surface and in the adjacent +sidewalk vaults, but no damage was done to the structural portions of +the buildings. + +While the above work had been going on westward from Fifth Avenue, the +excavation of the Twin Tunnel eastward from the end of the open-cut +section at Sixth Avenue had been proceeding rapidly, and, toward the end +of the difficult Fifth Avenue work, it was being attacked from both +directions. + + +PROGRESS OF EXCAVATION. + +Owing to the numerous sections of poor rock, interspersed throughout the +work with stretches of sound rock, the progress of the excavation was +very irregular, especially in 32d Street. The rate of excavation in good +ground is shown in Table 1. In the sections of bad ground, the +operations of excavation, timbering, and lining were often carried on +alternately, and it is impracticable to include them in the table. + +TABLE 1.--PROGRESS AND METHODS OF EXCAVATION IN GOOD GROUND. + +THIRTY-THIRD STREET. + +============================================================ + 1 | 2 | 3 | +-----------------------------+--------+--------------------+ + | | | + | | | + Type of excavation. |Tunnels.| Worked from: | + | | | + | | | +-----------------------------+--------+--------------------+ +Full-sized single tunnel | B | 1st Ave. shaft. | + | | | +Full-sized single tunnel | A | 1st Ave. shaft. | + | | | +Full-sized twin tunnel |A and B | 1st Ave. shaft. | + | | | + | | | + | | | +Full-sized twin tunnel |A and B |Intermediate shaft. | + | | (West of shaft.) | + | | | + | | | +Full-sized twin tunnel |A and B |Intermediate shaft. | + | | (East of shaft.) | + | | | + | | | +Full-sized twin tunnel |A and B |Intermediate shaft. | + | | (East of shaft.) | + | | | + | | | +Exploration drift |A and B |Intermediate shaft. | + | | (West of shaft.) | + | | | +Twin tunnel. Enlargement |A and B | West shaft. | + of exploration drift | | (East of shaft.) | +=============================+========+===================== + +====================================================================== + 4 | 5 | 6 | 7 | +----------------------------------+--------+------------+------------+ + | | Length | Average | + DATES. | Time | tunnel | advance | +----------------------------------|elapsed,| excavated, | per day, | + | | in | in | in | + From | To | days. |linear feet.|linear feet.| +----------------------------------+--------+------------+------------+ +Feb. 28, 1906. |May 12, 1906. | 74 | 346 | 4.7 | + | | | | | +Feb. 28, 1906. |Apr. 30, 1906. | 62 | 255 | 4.1 | + | | | | | +Aug. 23, 1906. |Jan. 5, 1907. | 136 | 789 | 5.8 | + | | | | | + | | | | | + | | | | | +Apr. 4, 1906. |Oct. 31, 1906. | 210 | 730 | 3.5 | + | | | | | + | | | | | + | | | | | +Apr. 4, 1906. |Oct. 31, 1906. | 210 | 783 | 3.7 | + | | | | | + | | | | | + | | | | | +Nov. 1, 1906. |Dec. 26, 1906. | 56 | 311 | 5.5 | + | | | | | + | | | | | + | | | | | +Mar. 1, 1907. |July 23, 1907. | 145 | 947 | 6.5 | + | | | | | + | | | | | +Sept. 6, 1907. |Dec. 4, 1907. | 89 | 603 | 6.8 | + | | | | | +===============+==================+========+============+============= + +===================================================== + 8 +----------------------------------------------------- + + + Methods and conditions. + + +----------------------------------------------------- +Top heading and bench. Muck loaded by hand. + + " " " " " " " " + +Top full-width heading and bench. Muck loaded + by steam shovel. Working exclusively on this + heading. + +Top center heading and bench. Muck loaded by + steam shovel. Working alternately in headings + east and west of the shaft. + +Top center heading and bench. Muck loaded by + steam shovel. Working alternately in headings + east and west of the shaft. + +Top full-width heading and bench. Muck loaded + by steam shovel working exclusively on this + heading. + +Exploration drift about 9 ft. by 12 ft. Mucking + by hand. Fourteen timber bents were placed in + March, and seven in April, 1907. + +Drift excavated to full width and bench. Muck + loaded by steam shovel. +===================================================== + + +THIRTY-SECOND STREET. + +============================================================ + 1 | 2 | 3 | +-----------------------------+--------+--------------------+ + | | | + | | | + Type of excavation. |Tunnels.| Worked from: | + | | | + | | | +-----------------------------+--------+--------------------+ +Full-sized single tunnel | C | 1st Ave. shaft. | + | | | +Full-sized single tunnel | D | 1st Ave. shaft. | + | | | +Full-sized twin tunnel |C and D | 1st Ave. shaft. | + | | | + | | | + | | | +Narrowed twin tunnel | C |Intermediate shaft. | + | | (East of shaft.) | + | | | + | | | +Narrowed twin tunnel | C |Intermediate shaft. | + | | (East of shaft.) | + | | | + | | | + | | | + | | | +Full-sized twin tunnel |C and D |Intermediate shaft. | + | | (West of shaft.) | + | | | +Exploration drift |C and D |Intermediate shaft. | + | | (West of shaft.) | + | | | +Twin tunnel. Enlargement }|C and D |{ Eastward from | + of exploration drift }| |{ open cut. | + | | | +Twin tunnel. Enlargement }|C and D |{ Eastward from | + of exploration drift }| |{ open cut. | + | | | +=============================+========+===================== + + + +==================================+========+============+============= + 4 | 5 | 6 | 7 | +----------------------------------+--------+------------+------------+ + | | Length | Average | + DATES. | Time | tunnel | advance | +----------------------------------|elapsed,| excavated, | per day, | + | | in | in | in | + From | To | days. |linear feet.|linear feet.| +----------------------------------+--------+------------+------------+ + Jan. 25, 1906.|Apr. 30, 1906. | 95 | 367 | 3.9 | + | | | | | + Jan. 27, 1906.|Apr. 30, 1906. | 93 | 354 | 3.8 | + | | | | | +{May. 22, 1906.|July 24, 1906.[E]}| 173 | 810 | 4.7 | +{Aug. 11, 1906.|Nov. 29, 1906. }| | | | + | | | | | + | | | | | + Mar. 19, 1906.|May 28, 1906. | 70 | 58 | 0.8 | + | | | | | + | | | | | + | | | | | +{May 29, 1906.|July 3, 1906.[E]}| 208 | 1,206 | 5.8 | +{July 18, 1906.|July 31, 1906. }| | | | +{Aug. 12, 1906.|Nov. 23, 1906. }| | | | +{Jan. 15, 1907.|Feb. 5, 1907. }| | | | +{Feb. 17, 1907.|Mar. 21, 1907. }| | | | + | | | | | + Dec. 1, 1905.|May. 10, 1906. | 161 | 225 | 1.4 | + | | | | | + | | | | | + Feb. 1, 1907.|Sept.13, 1907. | 225 | 1,033 | 4.6 | + | | | | | + | | | | | +}Feb. 1, 1908.|Feb. 14, 1908. | 14 | 65 | 4.6 | +} | | | | | + | | | | | +}Feb. 15, 1908.|Apr. 14, 1908. | 59 | 524 | 8.9 | +} | | | | | + | | | | | +====================================================================== + +[Footnote E: Time and distance omitted while working +through timbered stretches.] + +======================================================= + 8 +------------------------------------------------------- + Methods and conditions. +------------------------------------------------------- +Top heading and bench. Muck loaded by hand. + + " " " " " " " " + +Double heading and bench. Muck loaded by steam + shovel. Stretches aggregating 200 ft. narrowed + to about 25 ft. and later enlarged are included. + +Excavation about 30 ft. wide. Top full-width heading + and bench. Muck loaded by hand. Steam shovel + not installed. + +Excavation about 30 to 35 ft. wide. Top full-width + by hand and part by steam shovel. + + + + +Double heading and bench. Part of the muck handled + by hand and part by steam shovel. + +Exploration drift about 10 ft. by 13 in. Muck loaded by + hand. 14 ft. timbered. + +At portal of twin tunnels. Drift excavated to full + width and bench. Muck loaded by hand. 12 ft. + timbered. + +Drift excavated to full width and bench. Muck loaded + by steam shovel. Full-width tunnel timbered for 26 + ft. independently of the main excavation. +======================================================= + + +THREE-TRACK TUNNEL EXCAVATION. + +When it became evident that the work through the Fifth Avenue section +would be extremely slow, shafts were sunk in each street between Sixth +and Seventh Avenues. The shafts, as shown on Plate XIV, were located in +the streets, but in such a way as to block only half of the roadway. At +the same time it was decided to construct in open cut about 200 ft. of +the Three-Track Tunnel at the west end of the contract in 32d Street, +where the rock surface was below the top of the tunnel. It was hoped +that the remainder of the work could be built without opening the +street, but further investigation showed that this was impracticable, +and eventually all the Three-Track Tunnel in 32d Street, except 120 ft. +east of the shaft, was built in open cut. + +_Thirty-second Street Work in Tunnel._--Following the sinking of the +shaft, a drift was driven across the street at the crown of the tunnel, +and a top heading on the south side was excavated in both directions. +Frequent cross-drifts to the north side showed that the rock was nowhere +very sound and that, except for a short distance east of the shaft, it +was distinctly unfavorable for the wide Three-Track excavation. In this +stretch the north ends of these cross-cuts were connected by a second +heading, and wall-plates and sets of three-segment arch timbering were +set up to support the roof of the drifts. The cross-cuttings were +gradually widened and timbered until the entire excavation had been made +down to the level of the wall-plates, as shown in Fig. 3, Plate LX. The +bench was then excavated in two lifts, leaving the wall-plates supported +on narrow longitudinal berms, which were removed in short sections to +permit the placing of posts under the wall-plates. + +_Thirty-second Street Open-Cut Work._--Before actual open-cut excavation +was started, all buildings facing it were underpinned to rock. For this +purpose, a trench was dug along the face of the buildings and of the +same depth as their cellars. Holes were cut in the front foundation +walls through which long needle-beams (Fig. 4, Plate LX) were inserted +and jacked up on blocking placed on the cellar floor and in the trench, +until the weight of the building had been taken off its foundations. A +close-sheeted trench was then sunk to rock under the front building +walls, and a light rubble masonry retaining wall was built in it to +support the building permanently. Frequently, the excavation for the +underpinning wall, which was taken out in sections from 30 to 40 ft. +long, and in places was carried to a depth of 40 ft., was very +troublesome on account of the large quantity of water encountered and +the fineness of the sand, which exhibited a tendency to flow when +saturated. + +The Elevated Railroad columns in Sixth Avenue, near the north and south +lines of 32d Street, were underpinned in a manner similar to the +building foundations, while those on the center line of the street were +supported by girders riveted to them close under the track level. The +girders in turn were supported on posts footed on the new underpinning +of the adjacent columns. On the completion of the tunnels, concrete +piers were built up from the roof of the tunnel to form a permanent +foundation for the center-line columns. The area to be excavated under +Sixth Avenue was enclosed by a rubble masonry retaining wall constructed +in a trench. + +Open-cut excavation was started by planking over the street on stringers +resting on transverse 12 by 12-in. caps. The caps were gradually +undermined and supported on temporary posts which were then replaced by +short posts resting on 12 by 12-in. sills about 7 ft. below the cap. The +operation was then repeated and the sill was supported on another set of +short posts resting on a second sill. When the excavation had been +carried down in this manner to the level of the top of the tunnel, +diagonal 3 by 10-in. timbers were cut in between the posts and sills to +form a species of double A-frame, the legs of which rested in niches cut +in the rock and on posts carried up the face of the underpinning wall, +and the whole was stiffened with vertical tie-rods. This construction is +shown by Fig. 3, Plate LXII. The brick sewer was replaced temporarily by +one of riveted steel pipe. This pipe and the water and gas pipes and +electric conduits were suspended from the timbers as the pipes were +uncovered. + +Excavation in rock was made by sinking a pit to sub-grade for the full +width of the tunnel and advancing the face of the pit in several lifts, +the muck being blown over the slope and loaded into buckets at its foot. + +The work was attacked at several places simultaneously, and the spoil +was hoisted by derricks located at convenient points along the side of +the cut. + +_Thirty-third Street Work in Tunnel and Open Cut._--The West 33d Street +Shaft was similar to the one in 32d Street, and was sunk during +February, March, and April, 1907, through 10 ft. of earth, 21 ft. of +soft rock, and 29 ft. of fairly hard rock. It was necessary to timber +heavily the upper 30 ft. of the shaft. The timber later showed evidences +of severe strain, and had to be reinforced. + +[Illustration: Plate LXI.--EXCAVATION AND TIMBERING IN HEAVY GROUND +OF THREE-TRACK TUNNEL OF 33D ST.] + +As soon as the shaft excavation was deep enough, a drift was driven +part way across the tunnels, and top headings were started both east and +west to explore the rock. The heading to the west was divided into two +drifts, as shown on Plate LXI. These two drifts were continued to the +west end of the contract, and were then enlarged to a full-sized heading +and timbered, as shown on Plate LXI and Fig. 3, Plate LX. The rock near +the shaft contained many wet rusty seams, and settlement was detected in +the segmental tunnel timbering soon after the widening of the heading +was completed. Short props were placed under the timbers, and the street +surface was opened with a view of stripping the earth down to the rock +and thus lightening the load on the timbering. Street traffic was +maintained on a timber structure with posts eventually carried down to +the rock surface, and the walls of the buildings on the north side of +the street were underpinned to rock. The settlement of the tunnel +timbering was checked for a time, and the bench was excavated as shown +on Plate LXI. In this work the cut in the center was first made, and the +short props were replaced by struts, as shown; after this the berms were +removed and the side posts were placed. While building the brick arches, +holes were left in the masonry around the struts. After the masonry had +hardened, piers were built on the arches to support the segmental +timbers. The struts were then removed and the openings filled with +masonry. The voids above the arch were packed with rock and afterward +thoroughly grouted. + +The timbers near the shaft continued to settle, and, although they had +been placed from 9 to 12 in. above the level of the top of the masonry, +by October 1st, they encroached 9 in. within the line of masonry. It was +then decided to remove the rock for a distance of 48 ft. west of the +shaft, and build this portion of the tunnel in open cut. The posts +supporting the deck forming the street surface were replaced by an +A-frame structure similar to that developed for the 32d Street open cut, +without interruption of the street traffic. + +After making the open cut to the westward of the shaft, there was a slip +in the rock north of and adjoining the shaft. Fortunately, the timbers +did not give way entirely, and no damage was done. The open cut was +extended eastward for a distance of 46 ft., making the total length of +tunnel built in open cut on this street 94 ft. + +East of the shaft, for a distance of about 125 ft., the rock was broken +and could not be excavated to full size without timbering the roof, but +between this section of poor rock and those already mentioned in +connection with the work at Fifth Avenue, there was a stretch of 600 ft. +of good rock where all the spoil was handled with a steam shovel. + + +TWIN-TUNNEL LINING. + +The masonry lining for the tunnels was not started until the late fall +of 1906, after excavation had been in progress for a year and a half. At +that time concreting was started in the single tunnels westward from the +First Avenue Shafts, and by spring was in full swing in the Twin +Tunnels. + +The plans contemplated the use of a complete concrete lining except +where large quantities of water were encountered; in which case the +arches, beginning at a point 15 deg. above the springing line, were to be +built of vitrified paving brick. By reference to Plate XII it will be +seen that the water-proofing, which in the concrete-roof tunnels +extended the full height of the sides to the 15 deg. line, was carried in +the brick-roof tunnels completely around the extrados of the arch. The +cross-sections also show the location of the electric conduits which +were buried in the mass of the side and core-walls and which limited the +height to which the concrete could be carried in one operation. + +The same general scheme of operations was used wherever possible +throughout the Twin-Tunnel work, but was subject to minor modifications +as circumstances dictated. Concrete was first deposited in the bottom, +to the grade of the flow line of the drains; after it had set, +collapsible box forms, of 2-in. plank with 3-in. plank tops, were laid +on it to form the ditch and the shoulders for the flagstone covers. The +track, which had previously been blocked up on the rock between the +ditches, was raised and supported on the ditch boxes above the finished +floor level. At the same time, light forms were braced from the ditch +boxes to the grade of the base of the low-tension and telephone-duct +bank. After depositing the concrete to this level, the telephone ducts +were laid. + +The forms for the water-proofing or sand-wall up to the 15 deg. line and for +the main side-walls and core-walls were built in 30-ft. panels and were +supported on carriages, which, traveling on a broad-gauge track above +the ditches, moved along the tunnel, section by section, as the work +advanced. The panels were hung loosely from joists carrying a platform +on the top chord of the carriage trusses, and were adjusted +transversely by bracing and wedging them out from the carriage. The +small forms for the refuge niches, ladders, etc., were collapsible, and +were spiked to the main panel forms just previous to the deposition of +the concrete. The concrete was deposited from the platform on top of the +carriage, to which the cars were elevated in various ways. Plate LXI +shows the details of the carriages, and is self-explanatory. + +The concrete for the sand-walls and the core-wall, to the level of the +sidewalk, was deposited at the same time; two carriages in each tunnel, +placed opposite each other, forming a 60-ft. length, were used at each +setting. The floor section of the 4-in. tile drains had been laid with +the floor concrete, and, as the sand-wall concrete was deposited, the +drains were brought up simultaneously, broken stone being deposited +between the tile and the rock to form a blind drain and afford access to +the open joints of the tile for the water entering the tunnel through +seams in the rock. The drains were spaced at intervals not exceeding 25 +ft., depending on the wetness of the rock, and were placed at similar +intervals in the core-wall under the lowest projecting points of the +rock on the center line between the tunnels. A small ditch lined with +loose 6-in. vitrified half pipe was provided in the top of the sand-wall +to collect the water from the extrados of the arch and lead it to the +top of the drains. Great difficulty was experienced in maintaining these +drains clear, and, on completion of the work, a large amount of labor +was expended in removing obstructions from the floor sections, the only +portion then accessible. + +After water-proofing the sand-walls and laying the low-tension ducts, a +second pair of carriages, with panels on one side only, for 60 ft. of +side-wall and skewback to the 15 deg. line, were set and braced against the +core-wall. These forms are shown in connection with the carriage on +Plate LXI. They were concreted to the base of the high-tension duct +bank, and, after the concrete had hardened and the bank of ducts had +been laid, the concreting was completed in a second operation. + +In places where the roof was supported temporarily by posts and heavy +timbering, such as at Fifth Avenue, the form carriages could not be +used, and special methods were devised to suit the local conditions. +Usually, the panels were stripped from the carriages and moved from +section to section by hand, and, when in position, were braced to the +timbering. + +The arch centers were built up of two 5 by 3 by 3/8-in. steel angles, +and, when set, were blocked up on the sidewalks opposite each other in +the two tunnels. A temporary platform was laid on the bottom chord +angles of the ribs, on which the concrete was dumped, the same as on the +form carriages. The lagging used was 3 by 3-in. dressed pine or spruce +16 ft. long, and was placed as the concreting of the arch proceeded +above the 15 deg. line on the side-wall and above the sidewalk on the +core-wall. After the arch had reached such a height that the concrete +could not be passed over the lagging directly from the main platform, it +was cast on a small platform on the upper horizontal bracing of the +centers, shown in Fig. 3, Plate LIX, and was thence shoveled into the +work. In the upper part of the arch the face of the concrete was kept on +a radial plane, and, when only 3 ft. remained to be placed, it was keyed +in from one end, the key lagging being set in about 5-ft. lengths. The +arches were concreted usually in 60-ft. lengths. + +Where brick arches were used, the core-wall skewback was concreted +behind special forms set up on the sidewalks, or the arch ribs and +lagging were used for forms, and the brick arch was not started until +after the concrete had set. In laying the brick in the arch, the five +courses of the ring were carried up as high as the void between the +extrados and the rock would permit and still leave a working space in +which to place the water-proofing. This was usually not more than 3 ft., +except on the core-wall side. The felt and pitch water-proofing was then +laid for that height, joined to the previous water-proofing on the +side-walls, and was followed by the brick armor course over the +water-proofing and by the rock packing, after which another lift of +brick was laid and the operations were repeated. The large void (Fig. 1, +Plate LXII) above the core-wall gave convenient access for working on +top of the adjacent sides of the roof, and the keying of the arches and +the water-proofing and rock packing above the core-wall were usually +carried on from that point, the work progressing from one end. + +The concrete for all work above the floor was dumped on the platform of +the carriages, to which it was transported in the early part of the work +in cars running on a high-level track laid on long ties, resting on the +finished sidewalks. This arrangement, although requiring a large amount +of timber for the track, permitted the muck to be carried out on the +low-level track without interference. Later, when the advance of the +heading had ceased and the heavy mucking was over, all concrete was +transported on the floor level, and the cars were lifted to the carriage +platforms by elevators and were hauled by hoisting engines up a movable +incline. The latter method is shown by Fig. 3, Plate LIX. + +_Water-Proofing._--The water-proofing referred to above was in all cases +felt and pitch laid with six thicknesses of felt and seven of pitch. The +sub-contractor for the work was the Sicilian Asphalt Paving Company. All +joints were lapped at least 1 ft., and, where work was suspended for a +time and a bevel lap could not be made, the edges of the felt were left +unpitched for 1 ft. and the newer work was interlaced with the old. This +method was not always successful, however, on account of the softening +of the unpitched felt on long-continued exposure to the water. The felt +used was mainly "Tunaloid," together with some "Hydrex." It weighed +about 12 lb. per 100 sq. ft. when saturated and coated on one side only, +and contained about 25% of wool. The coal-tar pitch used had a melting +point of 100 deg. Fahr. + +After the completion of the tunnel, the concrete arch showed some +leakage and in places unsightly lime deposits. It was determined to +attempt to stop these leaks by the application of a water-proof cement +coating on the intrados of the arch. Extended experimental application +of two varieties of materials used for this purpose--"Hydrolithic" +cement and the U. S. Water-proofing Company's compound--have been made +with apparent success up to the present time, and the results after the +lapse of a considerable period are awaited with interest. + +_Duct Laying._--The position of the electric conduits, buried in the +heart of the concrete walls, interfered greatly with the economical and +speedy placing of the lining, and their laying proved to be one of the +most troublesome features of the work. The power conduits were +single-way, with the bank for high-tension cables separated in the +side-walls from the low-tension bank, as shown on Plate XII. The +conduits for telephone and telegraph service were four-way, and were +located in the core-wall. All ducts had 3/4-in. walls and a minimum +clear opening of 3-3/8 in. square, with corners rounded. They were laid +with joints broken in all directions, and in about 1/4-in. beds of +1:2-1/2 mortar. Flat steel bond-irons, 2 by 1/8 in., with split and bent +ends, were placed in the joints at intervals of 3 ft. and projected into +the concrete 3 in. on each side, tying together the concrete on opposite +sides of the ducts. The joints were wrapped with a 6-in. strip of +10-oz. duck saturated with neat-cement grout, and, in addition, the +power conduits were completely covered with a 1/2-in. coat of mortar to +prevent the intrusion of cement and sand from the fluid concrete. The +four-way conduits were plastered only over the wraps. Splicing chambers +were provided at intervals of 400 ft. + +[Illustration: PLATE LXII, FIG. 1.--WATER-PROOFING OVER BRICK +ARCHES.] + +[Illustration: PLATE LXII, FIG. 2.--TRESTLE USED IN CONCRETING IN +THREE-TRACK TUNNEL.] + +[Illustration: PLATE LXII, FIG. 3.--METHOD OF STREET SUPPORT OVER +OPEN-CUT EXCAVATION.] + +[Illustration: PLATE LXII, FIG. 4.--JUNCTION OF TWIN AND THREE-TRACK +TUNNELS.] + + +THREE-TRACK TUNNEL LINING. + +In the Three-Track Tunnels, a heavy brick arch was used for those +portions constructed in tunnel, while, in the open-cut sections, the +roof was of concrete. Both were completely water-proofed on the roof and +sides, and in the tunnel sections the space above the brick roof was +filled with rock packing. On account of the unstable nature of the rock +encountered throughout, the voids in the packing were afterward filled +with grout. + +By reference to the cross-sections, Plate XII, it will be seen that the +haunches of the arch were tied together by steel I-beams anchored in the +concrete, with the object of making the structure self-supporting in the +event of the removal of the adjacent rock for deep cellar excavations. +This construction materially influenced the contractor's method of +placing the masonry lining. + +After depositing the floor concrete, by the same method that was used in +the Twin Tunnels, a timber trestle (Fig. 2, Plate LXII) was erected to +the height of the underside of the I-beam ties, the posts being footed +in holes, about 3 in. deep, left in the concrete floor to prevent +slipping. In the open-cut sections the sand-wall forms were of undressed +plank tacked to the studding and braced from the trestle; in the tunnel +section they were spiked to the face of the posts supporting the +timbering. + +The side-wall forms were made up in panels about 3 by 10 ft., and were +clamped to studs by U-shaped irons passing around the stud and bolted to +the cleats on the back of the panels, the studs being braced from the +trestle. The side-wall concrete was deposited in three sections. The +first was brought up just above the sidewalk and formed the bench for +the high-tension ducts; the second carried the wall up to the springing +line. Before placing the third section the I-beam ties were set in +position (Fig. 3, Plate LXII) on top of the trestle, and the reinforcing +rods in the haunch of the arch were hung from them. The concrete was +carried up to a skewback for the arch, as shown in the brick-roof +cross-section (Plate XII) and embedded the ends of the ties. + +The centers for the arches stood on the I-beam ties, and the tops of the +hangers, for the permanent support of the ties near their center, were +inserted through the lagging. The brick arch, water-proofing, and rock +packing were laid up in lifts, in the same manner as in the Twin Tunnel, +with grout pipes built in at intervals of about 8 ft. The concrete arch +was placed in sections, from 25 to 50 ft. in length, with a rather wet +mixture and a back form on the steep slope of the extrados. + +The concrete for the sand-walls and lower part of side-walls was handled +on tracks and platforms laid on cantilever beams at mid-height of the +trestle, as shown by Fig. 3, Plate LXII. For the walls above the +springing line, the tracks were laid on top of the I-beam ties, and some +of the arch concrete, also, was delivered from the mixer at that level +and hauled up an incline to the level of the top of the arch. By far the +greater part, however, was turned out from mixers set on the completed +arch, and was transported on tracks hung in part from the street +timbering. + +_Completion._--Except in the heavily-timbered portions, such as at Fifth +Avenue, where the load had to be transferred from posts to the completed +masonry section by section, the lining of the tunnels presented no +special difficulty. The large number of small forms to be set, and the +mutual interference of the concreting and duct-laying operations proved +to be the most troublesome features of the work. + +The restoration of the streets, public utilities, etc., at the open-cut +sections was a slow and tedious operation, but the tunnels themselves +were completed in March, 1909, 3 years and 10 months after the inception +of the work. The finished tunnels are shown by the photograph, Fig. 4, +Plate LXII, taken at the junction of the twin and three-track types. + +FOOTNOTES: + +[Footnote A: Presented at the meeting of December 1st, 1909.] + +[Footnote B: Of the paper by Mr. Noble.] + +[Footnote C: Of the paper by Mr. Noble.] + +[Footnote D: Of the paper by Mr. Noble.] + + + + + + +End of the Project Gutenberg EBook of Transactions of the American Society +of Civil Engineers, Vol. LXVIII, Sept. 1910, by James H. Brace and Francis Mason + +*** END OF THIS PROJECT GUTENBERG EBOOK TRANSACTIONS OF THE AMERICAN *** + +***** This file should be named 19037.txt or 19037.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/1/9/0/3/19037/ + +Produced by Juliet Sutherland, Jacqueline Jeremy and the +Online Distributed Proofreading Team at http://www.pgdp.net + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. Special rules, +set forth in the General Terms of Use part of this license, apply to +copying and distributing Project Gutenberg-tm electronic works to +protect the PROJECT GUTENBERG-tm concept and trademark. Project +Gutenberg is a registered trademark, and may not be used if you +charge for the eBooks, unless you receive specific permission. If you +do not charge anything for copies of this eBook, complying with the +rules is very easy. You may use this eBook for nearly any purpose +such as creation of derivative works, reports, performances and +research. They may be modified and printed and given away--you may do +practically ANYTHING with public domain eBooks. Redistribution is +subject to the trademark license, especially commercial +redistribution. + + + +*** START: FULL LICENSE *** + +THE FULL PROJECT GUTENBERG LICENSE +PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK + +To protect the Project Gutenberg-tm mission of promoting the free +distribution of electronic works, by using or distributing this work +(or any other work associated in any way with the phrase "Project +Gutenberg"), you agree to comply with all the terms of the Full Project +Gutenberg-tm License (available with this file or online at +http://gutenberg.org/license). + + +Section 1. General Terms of Use and Redistributing Project Gutenberg-tm +electronic works + +1.A. By reading or using any part of this Project Gutenberg-tm +electronic work, you indicate that you have read, understand, agree to +and accept all the terms of this license and intellectual property +(trademark/copyright) agreement. If you do not agree to abide by all +the terms of this agreement, you must cease using and return or destroy +all copies of Project Gutenberg-tm electronic works in your possession. +If you paid a fee for obtaining a copy of or access to a Project +Gutenberg-tm electronic work and you do not agree to be bound by the +terms of this agreement, you may obtain a refund from the person or +entity to whom you paid the fee as set forth in paragraph 1.E.8. + +1.B. "Project Gutenberg" is a registered trademark. It may only be +used on or associated in any way with an electronic work by people who +agree to be bound by the terms of this agreement. There are a few +things that you can do with most Project Gutenberg-tm electronic works +even without complying with the full terms of this agreement. See +paragraph 1.C below. There are a lot of things you can do with Project +Gutenberg-tm electronic works if you follow the terms of this agreement +and help preserve free future access to Project Gutenberg-tm electronic +works. See paragraph 1.E below. + +1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" +or PGLAF), owns a compilation copyright in the collection of Project +Gutenberg-tm electronic works. Nearly all the individual works in the +collection are in the public domain in the United States. If an +individual work is in the public domain in the United States and you are +located in the United States, we do not claim a right to prevent you from +copying, distributing, performing, displaying or creating derivative +works based on the work as long as all references to Project Gutenberg +are removed. Of course, we hope that you will support the Project +Gutenberg-tm mission of promoting free access to electronic works by +freely sharing Project Gutenberg-tm works in compliance with the terms of +this agreement for keeping the Project Gutenberg-tm name associated with +the work. You can easily comply with the terms of this agreement by +keeping this work in the same format with its attached full Project +Gutenberg-tm License when you share it without charge with others. + +1.D. The copyright laws of the place where you are located also govern +what you can do with this work. Copyright laws in most countries are in +a constant state of change. If you are outside the United States, check +the laws of your country in addition to the terms of this agreement +before downloading, copying, displaying, performing, distributing or +creating derivative works based on this work or any other Project +Gutenberg-tm work. The Foundation makes no representations concerning +the copyright status of any work in any country outside the United +States. + +1.E. Unless you have removed all references to Project Gutenberg: + +1.E.1. The following sentence, with active links to, or other immediate +access to, the full Project Gutenberg-tm License must appear prominently +whenever any copy of a Project Gutenberg-tm work (any work on which the +phrase "Project Gutenberg" appears, or with which the phrase "Project +Gutenberg" is associated) is accessed, displayed, performed, viewed, +copied or distributed: + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + +1.E.2. If an individual Project Gutenberg-tm electronic work is derived +from the public domain (does not contain a notice indicating that it is +posted with permission of the copyright holder), the work can be copied +and distributed to anyone in the United States without paying any fees +or charges. If you are redistributing or providing access to a work +with the phrase "Project Gutenberg" associated with or appearing on the +work, you must comply either with the requirements of paragraphs 1.E.1 +through 1.E.7 or obtain permission for the use of the work and the +Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or +1.E.9. + +1.E.3. If an individual Project Gutenberg-tm electronic work is posted +with the permission of the copyright holder, your use and distribution +must comply with both paragraphs 1.E.1 through 1.E.7 and any additional +terms imposed by the copyright holder. Additional terms will be linked +to the Project Gutenberg-tm License for all works posted with the +permission of the copyright holder found at the beginning of this work. + +1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm +License terms from this work, or any files containing a part of this +work or any other work associated with Project Gutenberg-tm. + +1.E.5. Do not copy, display, perform, distribute or redistribute this +electronic work, or any part of this electronic work, without +prominently displaying the sentence set forth in paragraph 1.E.1 with +active links or immediate access to the full terms of the Project +Gutenberg-tm License. + +1.E.6. You may convert to and distribute this work in any binary, +compressed, marked up, nonproprietary or proprietary form, including any +word processing or hypertext form. However, if you provide access to or +distribute copies of a Project Gutenberg-tm work in a format other than +"Plain Vanilla ASCII" or other format used in the official version +posted on the official Project Gutenberg-tm web site (www.gutenberg.org), +you must, at no additional cost, fee or expense to the user, provide a +copy, a means of exporting a copy, or a means of obtaining a copy upon +request, of the work in its original "Plain Vanilla ASCII" or other +form. Any alternate format must include the full Project Gutenberg-tm +License as specified in paragraph 1.E.1. + +1.E.7. Do not charge a fee for access to, viewing, displaying, +performing, copying or distributing any Project Gutenberg-tm works +unless you comply with paragraph 1.E.8 or 1.E.9. + +1.E.8. You may charge a reasonable fee for copies of or providing +access to or distributing Project Gutenberg-tm electronic works provided +that + +- You pay a royalty fee of 20% of the gross profits you derive from + the use of Project Gutenberg-tm works calculated using the method + you already use to calculate your applicable taxes. The fee is + owed to the owner of the Project Gutenberg-tm trademark, but he + has agreed to donate royalties under this paragraph to the + Project Gutenberg Literary Archive Foundation. Royalty payments + must be paid within 60 days following each date on which you + prepare (or are legally required to prepare) your periodic tax + returns. Royalty payments should be clearly marked as such and + sent to the Project Gutenberg Literary Archive Foundation at the + address specified in Section 4, "Information about donations to + the Project Gutenberg Literary Archive Foundation." + +- You provide a full refund of any money paid by a user who notifies + you in writing (or by e-mail) within 30 days of receipt that s/he + does not agree to the terms of the full Project Gutenberg-tm + License. You must require such a user to return or + destroy all copies of the works possessed in a physical medium + and discontinue all use of and all access to other copies of + Project Gutenberg-tm works. + +- You provide, in accordance with paragraph 1.F.3, a full refund of any + money paid for a work or a replacement copy, if a defect in the + electronic work is discovered and reported to you within 90 days + of receipt of the work. + +- You comply with all other terms of this agreement for free + distribution of Project Gutenberg-tm works. + +1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm +electronic work or group of works on different terms than are set +forth in this agreement, you must obtain permission in writing from +both the Project Gutenberg Literary Archive Foundation and Michael +Hart, the owner of the Project Gutenberg-tm trademark. Contact the +Foundation as set forth in Section 3 below. + +1.F. + +1.F.1. Project Gutenberg volunteers and employees expend considerable +effort to identify, do copyright research on, transcribe and proofread +public domain works in creating the Project Gutenberg-tm +collection. Despite these efforts, Project Gutenberg-tm electronic +works, and the medium on which they may be stored, may contain +"Defects," such as, but not limited to, incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other intellectual +property infringement, a defective or damaged disk or other medium, a +computer virus, or computer codes that damage or cannot be read by +your equipment. + +1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right +of Replacement or Refund" described in paragraph 1.F.3, the Project +Gutenberg Literary Archive Foundation, the owner of the Project +Gutenberg-tm trademark, and any other party distributing a Project +Gutenberg-tm electronic work under this agreement, disclaim all +liability to you for damages, costs and expenses, including legal +fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT +LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE +PROVIDED IN PARAGRAPH F3. YOU AGREE THAT THE FOUNDATION, THE +TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE +LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR +INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH +DAMAGE. + +1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a +defect in this electronic work within 90 days of receiving it, you can +receive a refund of the money (if any) you paid for it by sending a +written explanation to the person you received the work from. If you +received the work on a physical medium, you must return the medium with +your written explanation. The person or entity that provided you with +the defective work may elect to provide a replacement copy in lieu of a +refund. If you received the work electronically, the person or entity +providing it to you may choose to give you a second opportunity to +receive the work electronically in lieu of a refund. If the second copy +is also defective, you may demand a refund in writing without further +opportunities to fix the problem. + +1.F.4. Except for the limited right of replacement or refund set forth +in paragraph 1.F.3, this work is provided to you 'AS-IS', WITH NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO +WARRANTIES OF MERCHANTIBILITY OR FITNESS FOR ANY PURPOSE. + +1.F.5. Some states do not allow disclaimers of certain implied +warranties or the exclusion or limitation of certain types of damages. +If any disclaimer or limitation set forth in this agreement violates the +law of the state applicable to this agreement, the agreement shall be +interpreted to make the maximum disclaimer or limitation permitted by +the applicable state law. The invalidity or unenforceability of any +provision of this agreement shall not void the remaining provisions. + +1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the +trademark owner, any agent or employee of the Foundation, anyone +providing copies of Project Gutenberg-tm electronic works in accordance +with this agreement, and any volunteers associated with the production, +promotion and distribution of Project Gutenberg-tm electronic works, +harmless from all liability, costs and expenses, including legal fees, +that arise directly or indirectly from any of the following which you do +or cause to occur: (a) distribution of this or any Project Gutenberg-tm +work, (b) alteration, modification, or additions or deletions to any +Project Gutenberg-tm work, and (c) any Defect you cause. + + +Section 2. Information about the Mission of Project Gutenberg-tm + +Project Gutenberg-tm is synonymous with the free distribution of +electronic works in formats readable by the widest variety of computers +including obsolete, old, middle-aged and new computers. It exists +because of the efforts of hundreds of volunteers and donations from +people in all walks of life. + +Volunteers and financial support to provide volunteers with the +assistance they need, is critical to reaching Project Gutenberg-tm's +goals and ensuring that the Project Gutenberg-tm collection will +remain freely available for generations to come. In 2001, the Project +Gutenberg Literary Archive Foundation was created to provide a secure +and permanent future for Project Gutenberg-tm and future generations. +To learn more about the Project Gutenberg Literary Archive Foundation +and how your efforts and donations can help, see Sections 3 and 4 +and the Foundation web page at http://www.pglaf.org. + + +Section 3. Information about the Project Gutenberg Literary Archive +Foundation + +The Project Gutenberg Literary Archive Foundation is a non profit +501(c)(3) educational corporation organized under the laws of the +state of Mississippi and granted tax exempt status by the Internal +Revenue Service. The Foundation's EIN or federal tax identification +number is 64-6221541. Its 501(c)(3) letter is posted at +http://pglaf.org/fundraising. Contributions to the Project Gutenberg +Literary Archive Foundation are tax deductible to the full extent +permitted by U.S. federal laws and your state's laws. + +The Foundation's principal office is located at 4557 Melan Dr. S. +Fairbanks, AK, 99712., but its volunteers and employees are scattered +throughout numerous locations. Its business office is located at +809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887, email +business@pglaf.org. Email contact links and up to date contact +information can be found at the Foundation's web site and official +page at http://pglaf.org + +For additional contact information: + Dr. Gregory B. Newby + Chief Executive and Director + gbnewby@pglaf.org + +Section 4. Information about Donations to the Project Gutenberg +Literary Archive Foundation + +Project Gutenberg-tm depends upon and cannot survive without wide +spread public support and donations to carry out its mission of +increasing the number of public domain and licensed works that can be +freely distributed in machine readable form accessible by the widest +array of equipment including outdated equipment. Many small donations +($1 to $5,000) are particularly important to maintaining tax exempt +status with the IRS. + +The Foundation is committed to complying with the laws regulating +charities and charitable donations in all 50 states of the United +States. Compliance requirements are not uniform and it takes a +considerable effort, much paperwork and many fees to meet and keep up +with these requirements. We do not solicit donations in locations +where we have not received written confirmation of compliance. To +SEND DONATIONS or determine the status of compliance for any +particular state visit http://pglaf.org + +While we cannot and do not solicit contributions from states where we +have not met the solicitation requirements, we know of no prohibition +against accepting unsolicited donations from donors in such states who +approach us with offers to donate. + +International donations are gratefully accepted, but we cannot make +any statements concerning tax treatment of donations received from +outside the United States. U.S. laws alone swamp our small staff. + +Please check the Project Gutenberg Web pages for current donation +methods and addresses. Donations are accepted in a number of other +ways including checks, online payments and credit card +donations. To donate, please visit: http://pglaf.org/donate + + +Section 5. General Information About Project Gutenberg-tm electronic +works. + +Professor Michael S. Hart is the originator of the Project Gutenberg-tm +concept of a library of electronic works that could be freely shared +with anyone. For thirty years, he produced and distributed Project +Gutenberg-tm eBooks with only a loose network of volunteer support. + +Project Gutenberg-tm eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the U.S. +unless a copyright notice is included. Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + +Most people start at our Web site which has the main PG search facility: + + http://www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. + +*** END: FULL LICENSE *** + |