CONSTRUCTION: On February 18, 1924, final plans and specifications were placed in the hands of prospective bidders. Upon opening the bids submitted by six engineering contracting firms, it was interesting to note that several of the bids were within $100,000 of the extimated $1,250,000 cost of the tunnel. On April 16 of that year the tunnel contract was awarded to Twohy Brothers of Portland, Oregon. Ground was broken at 10:00 AM on Saturday, May 3, 1924, at First Street and Glendale Boulvard. There were no official ceremonies, but PE was represented by D. W. Pontius, its Vice President & General Manager, and a number of the members of his official staff, including E. C. Johnson, Chief Engineer, who had directt supervision of construction. Also present were civic representatives from Los Angeles, Hollywood, Glendale, VAn Nuys, San Fernando, and Burbank.
Dirt from the first 500 feet of open cut at the western portal was removed by steam shovels and dump trucks. Lucas Street had to be realigned to avoid a grade crossing and this was done at that time. The first tunnel drift was commenced at the west portal on Friday, June 13th—possibley an omen of the subway's short service life.
The tunnel was excavated by the drift method; about 60% of the material excavated was loaded directly into dump cars without additional handling. A standard gauge spur track was built into the tunnel from the Glendale Line and with the construction of a trestle and bunkers, sufficient sotrage space was made for sand and gravel for use in the tunnel lining. A cement house and a small repair shop for emergency repairs were also constructed at that point.
Bunkers were also built on the southerly side of the open cut, with narrow gauge track running from these bunkers to the drifts. Dirt was was removed from the drifts with the use of small gasoline locomotives and specdailly constructed steel dump cars. These cars were of one yard capacity and specially designed by the contractor for rapid dumping and were built by a local firm. Loaded dirt cars were hauled from the tunnel to the bunkers, which were at a height sufficient to permit dump trucks to load underneath; it was then hauled away to local dumps.
In addition to starting work at the west portal, the contractor also made an open cut between Figueroa and Flower Streets, a distance of about 300 feet, and from this open cut worked drifts in each direction in the same manner as at the west portal. Thus the work was greatly speeded, as shifts could be worked continuously at each of the three headings. As the bottom of this open cut was some forty feet below street level, it was necessary to install a hoist to raise the excavated dirt into bunkers. The same type of small gasoline locomotives and steel dump cars wre used at this location.
Most of the tunnel excavation was through soft shale and this material was loosened by using low per cent dynamite in small quantities and by use of pneumatic air drills. Excavating proceeded by making two advance drifts, one on the lower right and one on the lower left of the face of the tunnel running about three cubic yards per lineal foot, each. Timbering to support these drifts was placed so othat the uprights were of sufficient distance apart to allow the passage of dump cars; the outside upright timber was placed at a sufficient distance from the outside excavation so that forms could be built and the concrete wall poured without disturbing these timbers. This timbering also formed the base for the timbering of the two following drifts immediately above the lower drifts, each of which contained about 2.3 cubic yards per lineal foot and also suported the inside forms for the concrete arch. All of these four drifts wre excavated to the outside line of concrete and found support against the core or center portion, which measured about 16 feet wide and 17 feet high and ran approximately 9.3 cubic yards per lineal foot. The third operation in excavation was the removal of the wings and arch which in most cases was acomplished in one operation, running approximately 4.8 cubic yards per lineal foot. Each drift as it progressed was decked over with lagging and the necessary portion of lagging removed to permit excavated material to drop into dump cars in the lower drifts by gravity.
Dynamiting was generally done during the noon hour or at the time of shift changes. No blasts were set off without warning, and a watchman was left to prevent workmaen from passing into the danger zone.
At no time did the gasoline locomotives enter the drifts. Empty cars were brought to within about 300 feet of the face of the drifts and were dropped into the lower drifts either by gravity or pushed by workmen. Loaded cars were pulled from the lower drifts by a cable leading to a hoist driven by an electric motor some 300 feet back from the drifts.
As the concrete lining was poured, set and stripped of form lumber, before the earth core was removed, the core was used for supporting the arch segnments upon which the concrete form lumber was placed. In very heavy and swelling ground, concreting always followed closely behind the wing and arch excavation.
Grades and lines were checked daily from substantial monuments which were established on the lines of the lower drifts at intervals of about 600 feet on tangent and about 150 feet on the curve. A daily drift record was kept by the engineer and coomputations made at the end of each month for payments to the contractor. These payments were based on lineal feet of drift progress.
The concret lining in the tunnel section had an inside clear opening at the top of rail of 28 feet and the spring line was 5'9" above top of rail. The arch had a radius of 14 feet with a minimum thickness of 24 inches and was reinforced with square deformed bars. The footings had a minimum width of 3'2" and extended 36" below the top of rail with an additional depth of 12 inches where wet ground was encountered. Four foot fiber ducts were provided in the side walls on each side for feeder and tension lines in connection with electrical operation, telephones, signals, etc. At 50 foot intervals along each side wall, a refuge access was provided.
This section extended from the western portal to a point 65 feet west of Olive Street. From that point to the west line of Olive Street the tunnel was flared by flattening the arch and from the west line of Olive Street heavy steel type construction was used, all footings, columns, and girders were designed to take the weight of a limit-height building.
All concrete in the tunnel section was composed of one part Portland Cement, three parts washed sand to five parts washed river gravel. Six-inch air lines were laid in the tunnel from large compressors and concrete was mixed and placed through these lines in one operation. A peice of rubber and cotton fabric, ten feet in length, was used as a depositing nozzle and it was an easy matter to deposit the concrete at any point in the forms.
The total length of the tunnel section was 4,325 lineal feet. The concrete lining contained 26,203 cubic yards of concrete, and the tunnel excavation was 135,000 cubic yards.
The contractor worked three shifts at each heading and daily total number of men employed amounted to about 650. The report of October, 1924, shows an average of approximately 24 lineal feet of completed tunnel daily.
Walls and arch were poured together, making a monolithic mass, except in one or two exceptional cases such as the open cut at Figueroa Street, at which point the walls were poured firStreet Pacific Electric furnished rock, sand, cement for the concrete lining; two spur tracks wre used for delivery of these materials: at the west portal and at the Figueroa Street open cut.
Water seepage into the tunnel which rose to about 24,000 gallons daily during the excavation period, gradually decreased to a flow of about 15,000 gallons daily. this heavy seepage puzzled the contractor, and the most plausible expalnation came from an old-timer: the water seeped down from Echo Park Lake, about a half-mile above the west portal on the Glendale Line. To get easy draingage an eight-inch main of concrete pipe with closed joints was placed for the full length of the tunnel on the center line between the tracks and about a foot below the sub-grade. Along each side of the tunnel 2 feet in from the walls a six inch concrete pipe was placed with open bell joints, and at intervals of 25 feet cross drains were laid of six-inch concrete pipe with open bell joints connecting the outside lines of pipe with the eight-inch main in the center between tracks. Over the top of all these drains for a depth of from twelve to eighteen inches, three inches crushed granite was placed to bring the floor of the tunnel up to the track sub-grade. The eight-inch amin led to sumps constructed under the sub-grade at Olive Street and at Flower Street; these sumps were equipped wuith electric automatic pumps which lifted water from the sumps to storm drains at these two points.
It took less than a a year to drive the the tunnel through to Hill Street. Ground was broken at the west portal on May 13, 1924, and the bore was completed on April 16, 1925. Then began the work of laying rail and instaling trolley wire.
The double track in the tunnel section was built on twelve foot centers. Ninety pound rail was used with standard tie plates and rail anti-creepers. Redwood ties of 6" by 8" and 8' were used and eight inches of crushed rock ballast was placed beneath the ties.
Electrification of the new tunnel involved some unusual features. Underground cables, running lengthwise through the tunnel walls, were first to be installed. A crew of "overhead" men was made over into a crew of "underground" men with much success; as this was a new line of work for them, it was necessary to obtain considerable new equipment. A standard cable-pulling winch was assembled in Torrance Shops, a steel pulling cable was saalvaged from elevator cables discarded at Sixth & Main Station; duct rods and other paraphernalia obtained and actual work started on June 25, 1925. By July 3rd a total of 24,000 feet of No. 14 rubber covered wire had been installed for the lighting system; 4,000 feet of No. 3 conductor, lead covered, 2,200 volt cable, and 8,000 feet of ten pair lead covered telephone cable had been pulled into their respective ducts, ready for the calbe splicers.
The trolley contact system was of catenary construction, and presented several interesting features. The supporting messengers were 300,000 c.m. copper cables, which also acted as auxiliary feeders. They were attached to the tunnel roof at 15 ft. intervals by means of porcelain suspension insulators of standard design. The trolley contact conductors were of 4/0 copper hung to the suporting messengers at 15 ft. intervals, midway between the messengers, by means of 6 inch type C.S. catenary hangers.
At intervals of 600 feet, taps were run up through the tunnel proper, the trolleys being held in alignment in the curve by the use of a new type of steady brace, developed in the electrical department of the PE and made in the Torrance Shops. This permitted the trolley wire to raise with the pressure of trolley poles, but prevented it from moving sideways. It consisted of a maple block fastened to the brackets by insulated bolts, with an iron arm, swiveled at each end, running down at an angle to a standard trolley ear. An iron plate was bolted on one side with a hook to carry the suporting messenger.
Lights in the tunnel were spaced at fifty foot intervals on both sides. They were put in the refuge pockets where men could step back in a recess in the wall. Every thousand feet a specially built refuge pocket housed a subway telephone connected directly to the terminal; colored lights designated these so they could be reached quickly in case of an emergency. The lighting system was fed at 1,500 foot intervals from transformers which also ran the signals. These transformers were tapped from the 2,200 volt cable by means of subway type terminal boxes which provided protection from failure.
A feature of the use of the new type of "steady brace" described above was that it permitted complete elimination of trolley span wires, always a source of trouble when trolley poles wander.
The five track terminal beneath the Subway Terminal Building employed a type of direct suspension, it being a slow speed zone. The 4/0 copper trolley wire was fastened by means of special spring-type barn hangers spaced every 15 feet on tangents, 7 feet on curves, to 2 X 12 inch planking, which in turn was suitabley atached to the cncrete beams of the ceiling. More than 2,000 lineal feet of Oregon pine planking were used. Trolley wire when installed was stretched to a tension of 2500 pounds, therby providing a perfectly horizontal under-run, even under the maximum pressure of the trolley wheel.
A new substation, Toluca No. 51, was constructed adjacent to the west protal to provide most of the power needed for the tunnel and terminal operation. This new unit, in addition to carrying the major portion of the tunnel-terminal load, also distributed all of the electrical energy required for the operation of the entire railway facilities in the reloacated Hill Street Station. Due to its location, the Toluca Substation relieved the existing heavy load on the Olive Substation and materially improved voltage conditions on the Holyywood and Glendale lines.
Toluca Sub was automatic, and was equipped with a 1500 kw., 600 volt DC, 6 phase, 50 cycle, 600 RPM compound wound synchronous converter, with complete automatic equipment, all of the most modern type and incorporating the latest developments in the industry. The building was of concrete cnstruction and absolutely fireproof. Its exterior design was considerably more atractive than the usual PE utilitarian design for such structures.
Toluca Substation was interconnected by means of feeders with the Maple Avenue, Olive, and Ivanhoe Substations. Suitable switching equpment was installed for operating the feeders, singly or collectively, thus providing a unified system and flexible electrical energy supply to meet the varying demand of an exceedingly diversified load.
In addition to the relays and other devices required for starting and shutting down the station machine under normal conditions, there were protective relays for limiting overloads and overspeeding; for disconnecting the machine in case of power failure, single phase operation and reversed polarity.
Toluca Substation cost $120,000 and first went in service on June 15, 1925.
Across the two main line tracks from the new substation was Toluca Yard, built in late 1925. The yard cntained four passenger car storage tracks with a total capacity of 22 cars. It had 1700 lineal feet of track, one inspection pit and miscellaneous maintenance facilities and storage sheds.
Safety was insured by 21 block signals, automatic train stops, and an interlocker plant at the throat of the terminal; this interlocker was located in a tower four stories below Olive Street. The automatic block signals were aranged to handle one train every 25 seconds.
The first work train operated through the tunnel and into the terminal on September 10, 1925.
Now we leave the tunnel and turn our attention to the great Subway Terminal.
CHRONOLOGICAL HISTORY OF CONSTRUCTION
Showing an elapsed time of but 18 months and 27 days from the date of breaking of ground to operation of the first scheduled passenger train, the following is a chronological table of important events in the construction of the tunnel and terminal:
Feb. 11, 1924 Plans completed for construction of tunnel and terminal
Feb. 18, 1924 Bids asked.
Mar. 18, 1924 Bids submitted by prospective contractors.
Apr. 16, 1924 Tunnel contract awarded.
May 3, 1924 First ground broken.
Jun. 13, 1924 First tunnel drift begun.
Jan. 2, 1925 Work on Toluca Substation begun.
Mar. 1, 1925 Completion of first drift.
Apr. 16, 1925 Tunnel bore completed.
May 13, 1925 Excavation for terminal building begun.
Jun. 23, 1925 Wiring of tunnel begun.
Jul. 4, 1925 Toluca Substation in service.
Jul. 7, 1925 Structural steel erection begun.
Aug. 23, 1925 Building excavation finished.
Aug. 31, 1925 Track laying in tunnel begun.
Sept. 10, 1925 Operation of first work train through to terminal.
Oct. 15, 1925 Laying of track finished.
Oct. 24, 1925 Structural steel erection finished.
Nov. 24, 1925 Wiring of tunnel finished.
Nov. 30, 1925 Official ceremonies and inspection by public.
Dec. 1, 1925 Operation of first scheduled pasenger train.
