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hydraulic-fill dam in the Colorado River at Hanlon Heading and
Yuma, are in no wise similar. At Yuma, scour is not influenced by
bed-rock, as stated by Mr. Ockerson, because bed-rock at this point is
at a considerably lower elevation than the bed-scour line, and a sample
of the materials deposited in the bed will reveal that they are graded
as to weight, increasing as the scour line is approached.

The construction of a temporary dam in the Colorado River at
Hanlon Heading became necessary once more in the summer of 1916.
The Irrigation District constructed a rock-fill dam rather than a
hydraulic-fill dam, similar to that built the year before, on account of
the lack of adequate equipment to permit of the latter type, and
because of the greater river discharge at the time the dam became
necessary.

The river discharges, throughout the period when the dam was
required, exceeded 30 000 sec-ft. The writer is of the opinion that with
the proper equipment, as outlined in the discussion of the paper, the
hydraulic-fill dam might have been placed successfully, at least with
sufficient success to have restricted the channel area and to have de-
veloped the necessary head for diversion of sufficient water into the
Imperial Valley Canal. As it was, a rock-fill dam was again placed
across the Colorado River and later removed, at a total cost of more
than $100 000.



AMERICAN SOCIETY OF CIVIL ENGINEERS

INSTITUTED 1S52



TRANSACTIONS



This Society is not responsible for any statement made or opinion expressed
in its publications.



Paper No. 1388

TUNNEL WORK ON SECTIONS 8, 9, 10, AND 11,

BROADWAY-LEXINGTON AVENUE SUBWAY,

NEW YORK CITY*

By Israel Y. Werbin, Assoc. M. Am. Soc. C. E.



With Discussion by Messrs. Maurice Griest, John H. Madden, Egbert
H. Jacobs, T. Kennard Thomson, John H. Myers, H. G. Moulton,
Robert Eidgway, C. Y. Y. Powers, Francis Donaldson, and
Israel Y. Werbin.

Synopsis.

This paper describes the work of excavating for and lining the
tunnels for the new Lexington Avenue Subway between 53d and 106th
Streets, in the Borough of Manhattan, City of New York. Inasmuch
as this work involved the driving of tunnels with large and unusual
cross-sections, through unsound rock, under busy city streets, and
the contract placed on the contractor absolute liability, it has been
thought worth while to record the methods used.

The tunnels were built to accommodate two and four tracks, the
two-track structure having a cross-section of 32 by 16 ft., the four-
track, double-deck structure, 32 by 32 ft., and the four-track struc-
ture with all tracks on one level, 60 by 16 ft.

The methods followed in excavating these tunnels through sound
and unsound rock and through soft ground are described. In some
cases, water was encountered in such quantities as to necessitate
the use of compressed-air methods, in order to prevent the loss of
materials and the settlement of the local track structure which had

* Presented at the meeting of September 20th, 1916.



343 SUBWAY TUNNEL WORK

previously been completed. The excavation for the four-track struc-
ture with the four tracks on the same level had to be made one
track at a time, and the manner of making this excavation and
protecting the finished part of the structure is described.

Information is also given as to drilling, loading and firing, tim-
bering, plant, cost, etc.

In connection with the lining of the tunnel with concrete, the
various types of forms are described; also the manner of handling
and placing the concrete.



General.



The Lexington Avenue Subway is being built by the City of New
York, under the supervision of the Public Service Commission for the
First District of the State of New York, and, when completed, will
be operated by the Interborough Rapid Transit Company in accordance
Vi'ith contracts entered into vsdth it by the City of New York acting
by the Public Service Commission.

For purposes of organization and construction, the route is divided
into sections averaging in length about thirteen or fourteen city
blocks.

Section 8 extends from 53d to 67th Street; Section 9 from 67th
to 79th Street; Section 10 from 79th to 93d Street; and Section 11
from 93d to 106th Street. The total length of the four sections is
13 992 ft.

The approximate quantity of tunnel excavation made on the four
sections was 250 000 cu. yd., and, at the contract prices, the cost
of doing this part of the work was approximately $2 250 000. The
total cost of all the work on the four sections was approximately
$10 500 000, exclusive of track, station finish, and equipment.

The rock encountered in the course of the work on these sections
was mostly Manhattan schist of varying degrees of hardness. Tlie
greater part of the tunnel being but a comparatively short distance
below the street surface, the rock was often blocky, and occasional
mud seams were encountered, requiring considerable timbering on
Sections 8 and 9. The rock on Sections 10 and 11 was fairly good,
and very little timbering was used for this part of the work.



PLATE IV.

TRANS. AM. SOC. CIV. ENGRS.

VOL. LXXXI, No. 1388.

WERBIN ON

SUBWAY TUNNEL WORK.




TYPICAL SECTIONS

IN TUNNEL.
LEXINGTON AVENUE
SUBWAY
,.i 530 TO 103D STREETS.



.VI STAJ'^

' .vio .003 '/^
■:f .on .ix/.>. -I

lOW J3MMUT YAA



!V)0IT033



I

r



subway tunnel woek 343

General Description of Subway Structure.

Several different types of subway structure were used on the four
sections. On Sections 8 and 9, the local and the express tracks are
in separate structures. The local tracks are immediately below the
street surface and the work was done by cut-and-cover methods; the
express tracks are in separate tunnels below the local tracks. The
distance from the street surface to the sub-grade of the express tracks
varies from 60 to 100 ft., and the distance between the two levels
from 10 to 55 ft., as shown on Plate TV.

The largest part of the structure on Sections 10 and 11 is double-
decked, the express being placed immediately below the local tracks.
This type prevails from 79th to 99th Street. In the station at 96th
Street, the upper level is widened to permit the construction of the
station platform (Plate IV). Going north from 99th Street, the
local tracks in the upper level diverge imtil at 100th Street they have
been offset sufficiently to clear the express tracks in the lower level.
The four tracks then continue northward on approaching grades
until at 103d Street they are on the same level, as shown on Plate IV.

Excavation for Two-Track Tunnel, Sections 8 and 9.

Excavation in Sound RocJc. — The excavation for these tunnels
through sound rock did not present any exceptional features. The
section was taken out with a center top heading and one or two
benches, depending on the height of the heading. The center heading
was about 9 by 14 ft., the drilling requiring from 24 to 32 holes,
depending on the hardness of the rock. Work was carried on continu-
ously for 24 hours per day, with three drilling shifts. The forces
were organized so that an advance of about 5 ft. would be made daily.
The details of the drilling, loading, and firing are shown on Plate V.

Excavation in Unsound Boch. — In a considerable part of the work,
the rock was hard but blocky, and would not permit of making the
excavation for the full section without timbering. In most of these
cases it was generally possible to excavate enough to permit the
erection of the structure for one track without timbering, and after
this part had been completed and the rock above had been caught up,
the remainder of the section was excavated and the structure com-
pleted. (Fig. 1.)



344 SUBWAY TUNXEL WOKK

Where the rock was seamy and disintegrated, however, the top
side-drift method of tmmeling was generally used, segmental timbering
being put in, as shown on Plate VI. The side-drifts were generally
about 7 by 11 ft. The wall-plates and timbering were set so as to
be entirely outside the neat line of the subway structure and there
would be no timbers bedded in the concrete lining inside the neat lines.
Where soft ground was encountered, poling boards were driven ahead
over the sets. The sets were placed about 2 ft. from center to center,
12 by 12-in. yellow pine timbers being used.

In the work on Section 8, where segmental timbering was used, the
center pieces of the sets were posted up from the bench, and, as the
latter was removed, new posts down to sub-grade were put in, as shown
by Fig. 3. In removing the bench, the holes were drilled close
together, and light charges of explosives were used in order to mini-
mize the possibility of knocking out the posts. Toward the close of
the job, in order to safeguard further this feature of the work, a
long, continuous girder was blocked up under the center cap, and
this was kept in place until the bench had been removed and new
posts, down to sub-grade, had been placed. (Fig. 2.)

On Section 9, after the top heading had been removed, the con-
tractor placed two (and in some cases three) pairs of 24-in. I-beams
longitudinally on the bench, and the caps were posted up from these
beams. (Fig. 4.) The beams were about 30 ft. long, and were spliced
so as to develop their full strength. As the bench was removed, posts
were placed under the beams down to the sub-grade. This system of
timbering had the advantage that the posts under the caps did not
have to be moved in order to make the excavation for the bench.
(Fig. 5.)

Often, where the ground was heavy enough to require timbering,
water was encountered, and it was desirable to keep this water away
from the concrete lining until it had had time to set. Accordingly,
the space between and back of the sets was packed with concrete, and
later grouted under about 90 lb. pressure. This procedure was
effective in keeping out most of the water, and also served to stiffen
up the timbering. The final lining was placed tight up against the
timber and concrete previously placed, and again grouted if necessary.
(Fig. G.)








LOADING DATA



Sticks Pounds



LondlDg
pounds.



24-HOLE *■



)ING



Yardage of heading.

Total linear tdet of drlU holes.

Total pounds of eO^Forcite.

Llcear feet of drill holes per cuWo yard.

Pounds of dynamite per linear foot of hole>

Pounds of dynamite per cubic yard.



Pull =5 £t.



LOADING DATA |


si


Desoriptlon


Jyi


605f Porcite. |


M-3


Loading


Loading




ot




3| 1




per foot








holes.




^-s


Sticks


Pounds


in
pounds.


4


Cut




12


5


3


0.429


2


Breaking





C


5


3


0.500


10
8
i


Side
Side
Dry


c

6


SO


5
6
3.S3


3


0.600
0.300
0.333


28-HOLE HEADING


Yardage of heading.


21.1


Total linear feet ot drill hoIeB.


172


Total pounds of COJSForcite.


80


Linear feet of drill boleB per cubic yard.


8.17


Pounds of dynamite per linear foot of hole.


0.4CC


Pounds of dynamite pet cubic yard.


3.79



LOADING DATA |


II


Description
ot
holes.


si
is


00? Porcite.


III


per hole.
SUoks Pounds


Loading
per toot

pounds.


8

G




Cut

Side (1)
Side (2)
Breaking
Dry


7.6
7.6
7.5
7.6


18
IS
11.4


0.25 3.75
5.U 10
5,0 3L0
&1C 1.9
3,50 2.1


a4C0
0.400
0.400
0.264
0,281


32-HOLE HEADING


Yardage of heading.

Total linear feet of drlU holes.

Total pounds of OO^Foroite.

Linear feet cf drill holes per cubic yard.

Pounds of dynamite per linear feet of hole.

Pounds of dynamite per cubic yard.


28.0
244

8.72
0.368
3.21



PLATE V.

TRANS. AM. SOC. CIV. ENGRS.

VOL. LXXXI, No. 1388.

Vv'ERBIN ON

SUBWAY TUNNEL V/ORK.





LOADING DATA |


Drill Holes


ii

as


^1


eOJGelati


a Dynan


lite


No.


Desorip-
Uon


Per hole.


Total


Pounds
pet
toot.


Sticks Pounds




CENTER HEADING






4

10

8


Cut

Breaking

Side

Side

Dry


7
6
6
6
6


23
12
60
43

24


5
5
5
5
3.33


3
3


12
6
30
24

8


0.4S9
0.500
0.500
0.500
0.333


SIDE-WINGS 1


7 lUb 1 8 1 56 1 6.61 1 4
2 |Dry | i | 14 | 6.62 | 3.3


"e.o


0.600
0.4-1 1


BENCH 1


11 1 Bench | 8 | 88 | 0.65 | 3.98


4.39


^0.498 1



QUANTITIES FOR A 6-FOOT ADVANCE |




Center 1 Side-
heodingj wings.


Bench


Total


Yardage


2S.1


26.


57.1


111.2


Total Unear feet of drill holes.


230








Total pounds of dynamite*


100.6


70.2


80.6


267.2


Linear feet of drill holes pet cubic yard.


8.17


6.50






Pounds of dynamite per foot ot bole.


0.406


0.492


0.617




Pounds of dynamite per cubic yard. | 8.79






2.32



CENTER HEADING DIAGRAMS AND TABLES.



SUMMARY

METHOD OF

TUNNEL EXCAVATION

2-TRACK TUNNEL

SOUND ROCK

SECTIONS 8 AND 9,



3J)




Fig. 1. — Construction in Poor Rock Tunnel. Half of Section Built at a Time,
Without Timbering.




Fig. 2. — Segmental Timbering Used on Section 8 ; also Types of Center Line
Steel Used in the Tunnel.



PLATE VI.

TRANS. AM. SOC. CIV. ENGRS.

VOL. LXXXI, No. 1388.

V/ERBIN ON

SUBWAY TUNNEL WORK.



3 between Tiuibei Arch Rm^ and Rock is packed
'tight with Block I u r , r I, I inlGi iited.



® ©

® © @ ®
© © © ®

J® (p ,(p ®

f® © ® © © ® W




NOTE;-

Figures indicate
order of firing
Used 70.3 lb of 60% Forcite
in both Drifts for o'pull.





DRILLING DIAGRAM
TOP HEADINGS.
Used about 23 Ih^for a pull of 4 in both
top helpings.

DRILLING AND LOADING DATA.



DRILLING DIAGRAM- DRIFTS.



SECTION SHOWING ORDER OF EXCAVATION.



For a pull of Al

Used in lb. of Dy.uamite.




METHOD OF EXCAVATING UPPER BENCH.



Note: (1 pull) nseJlS.S Ib.wt dynamite in
11 breaking holes and 30 trimming iiolea.



©




QUANTITIES PER LINEAR FOOT OF TUNNEL. |




East
and

drltls


and

top
beading.


Center
line


Top


Top and
bottom
lifts,
lower


Complete
section.


Vardn|.e.


5.17


4.00


1.11


4.58


9.TS


26,24


Total linear feet
o( driU holes.


72.


67.5


7.5


55.


100.5


301.5


Total poimda of
COHKorclte.


11.75


6.75


0.03


13.5


24,6


56.18


Linear feet of
holeflpet cuWoyard.


13.05


12.6


0.70


12.


Jl,2


ll.l>


Pounds of 60t dynamite
per cubic yard.


2.27


1.25


0.57


2.04


2.51


2.23


Linear feet of drill b »los per linear foot of 2-traok tunnel =■ 83.61. |



LOADING DETAILS. 1


Pull
fool


Holes,


Deptb,
la
feet.


Total
pounds,


Pounds
per
'bole.


loading

drilLbolo,
In pounds.


No. Deaorlptlon.


6


EAST


*ND WEST DRIFTS. ®




12
18
30


Out boles.
Elrscround,
Second round.


8 1 18.0
7 22,5
7 1 30.0


1.6
1.26
1.0


0.19
0,18
0.H


is


EAST AND


WEST TOP HEADINGS. (2) |


40 iHamraer.


,5 1 23.0 1 0.6


0,10 1


4


CENTER COHE. (3) 1


6 [Cut boles.


6 1 2.6 1 0.42


0,09 1


1


UPPER BENCH. ® 1


11 ICui'boles.
30 l-Trlmmlng.


6.6 1 9.5 1 0.87
t 4.0 0.13


ai8

OlSS


6


LOWER BENCH. TWO LIFTS, C6)


®


140 [Breaking.


4.5 1 147.0 1 1.01


0.23



METHOD OF EXCAVATIOM

IN

UNSOUND ROCK

2TRACK TUNNEL

SEOnONS 8 AND 9



SUBWAY TUXXEL WOEK



347



Excavation in Compressed Air. — At 57th. and 75tli Streets, streams
originally crossed Lexington Avenue, and when the excavation was
being made for the express timnels at these places, considerable water
was encountered. The contractors had completed the structure for




METHODS OF
TIMBERING IN
SEC. 8 TUNNEL



Fig. 3.



fi'3- Portal




J
l?il rods

SECTION m-m



final! STAGE



METHOD OF TIMBERING
IN TUNNEL
SECTION 9



Fig. 4.



the local tracks in the upper level at these points before the work
in the express tunnels was undertaken. This had been done in spite
of the fact, pointed out to them, that settlement in the local track
structure might result if soft ground carrying water was encountered



348 SUBWAY TUNNEL WOEK

in the excavation for the express tunnel. As the excavation ap-
proached the sites of the old streams at 75th Street, the top of the
section ran out of rock, and at 57th Street there were only a few
feet of rock cover over the heading. In both places considerable water
ran into the excavation, and the water, carrying with it some of
the material between the two levels, caused considerable settlement
in the local track structure, as well as some settlement in the build-
ings adjacent to the work. An attempt was made to control the
settlement by blocking up the roof of the local track structure and
by supporting the buildings temporarily on needles, also by pumping
the water through driven wells from the local track floor, but neither
of these methods proved satisfactory. It was decided finally to
proceed with the work under air pressure, by which method the ex-
cavation was completed successfully without any appreciable loss of
materials.

The details of the locks and bulkheads used at 57th Street are shown
on Fig. 7. The air pressure varied from 8 to 16 lb. Concrete
bulkheads, 3 ft. thick and reinforced with structural steel or iron
rails, were built into the finished section of the tunnel. A groove
about 6 in. deep was cut into the concrete lining of the tunnel, and
the bulkheads were bonded into it. The lock and the pipes for air,
drainage, etc., were built into the bulkheads.

The excavation under air pressure was confined to the removal of
the top heading. After the timber sets had been placed and the
space between and back of the timbers had been concreted and grouted,
the bench was removed in free air.

At 57th Street, where the section did not run out of rock, the
excavation under air pressure was made by the top side-drift method,
as described for the unsound rock tunnels on Section 8.

At 75th Street, the top of the heading was driven through soft
ground, and poling boards were used. The general method of pro-
cedure (Fig. 8) was about as follows: The excavation was started at
the center and carried over to the sides. Poling boards, about 4 ft.
long, were driven over the caps, and, as the excavation was carried
from the center to the sides, breast boards were placed against the
face of the heading and under the ends of the poling boards, until
the excavation had been widened enough to permit the placing of
another cap, after which the breast boards were removed and the




Fig. 5. — Method of Tunnel Timbbeing Used on Section 9.




Fig. 6. — Space Between Timber Sets Concreted.



SUBWAY TUNNEL WORK



351



operation was repeated. After three or four caps had been placed in
this way, the excavation was widened out for the wall-plates and
side-legs. Where considered necessary, lagging was placed and braced,
as shown on Fig. 8.





L /-Bench 2o3 + 26.



^



Note;- AH pipes proirided with valves.

Bulkhead reinforced with 60-lb. rails.



DETAILS
OF
28.6 BULKHEAD AND LOCKS
56TH-57TH STREETS-SEC. 8



Fig. 7.



In some cases, the soft ground showed a tendency to flow and work
its way in between the roof and breast boards, and in such cases
the cracks were stuffed with hay. At certain times there was con-
siderable difficulty in holding the air, and for this reason it often



352 SUBWAY TUNNEL WORK

became necessary to caulk the cracks between the timbers with oakum
and clay.

Working Shafts. — There were working shafts, for handling the
excavated material from the express tunnels on Sections 8 and 9, at
56th, 62d, 68th, 74th, and 78th Streets, the distances between shafts
being 1 605, 1 662, 1 518, and 1 057 ft., respectively. At 62d and 74th
Streets, the hoisting was done with electric traveling cranes; derricks
operated by electric hoists were used at the other shafts.

EoADWAY Support at Portals, Sections 10 and 11.

The tunnels on Sections 10 and 11 were not continuous, there being
stretches of open-cut work between them. The excavation was gen-
erally started at the cut-and-cover part of the work, and then extended
into the tunnels. The depth of the cuts between the portals varied
from 50 to 70 ft., and it became evident that some method of sup-
• porting the roadway, different from the usual one of posting up from
below, wotdd have to be used.

Two general methods of supporting the roadway were used. By
the first, 48-in. girders, 60 ft. long, were placed about 40 ft. apart
across the full width of the trench, with the ends resting on the rock
or on cribbing built up from the rock. Then 26-in. X-beams were
run longitudinally over the cross-girders, and the roadway was blocked
up from them. After the excavation was completed, the cross-girders
were posted up from below, as shown by Fig. 9. As an additional
precaution, 48-in. girders were placed longitudinally in the roadway
alongside of the curb, and the cross-girders were connected with them
by suspender rods and plates. The surface girders were spliced with a
joint designed to develop the full strength of the girder before it
would fail. One end of the longitudinal girder was supported by
being blocked up from a cross-girder that was already posted up
from below, and the other end rested on the undisturbed portion of
the roadway. As the excavation advanced, the longitudinal girders
were moved ahead, or an additional girder was spliced on.

By the second method, the longitudinal girders just described were
used, but 26-in. I-beams running crosswise were suspended from
them, and the roadway was blocked up from these cross-beams. The
beams were placed about 10 ft. from center to center, and, after the
excavation below was completed, the beams were posted up and the
longitvidinal girders moved ahead. (Fig. 10.)



SUBWAY TUNNEL WORK



353







354



SUBAVAY TUNXEL WORK





Fig. lO.^RoADWAY Supported on Cross-Beams, Sections 10 and 11.




Fig. 11. — Excavation in Double-Deck Tunnels.



subway tunnel tvokk 357

Excavation for Double-Deck Tunnel, Sections 10 and 11.

Tlie double-deck tunnel is 31 ft. 8 in. wide and 32 ft. 7 in. high.
The section was generally taken out with a center top heading and
three benches. An advance of from 5 to 8 ft. of heading was made at
each fire. About 8 lin. ft. of drill holes were required per cubic yard
of heading, and 1.6 ft. per cubic yard of bench. The approximate
arrangement of drill holes, and the loading and order of firing are
shown on the heading diagrams. Figs. 12 and 13.

The excavation was started with a 32-hole heading (Fig. 12),
but, owing to the severe concussion following the blasts, it was
found advisable to increase the number of holes to 48 (Fig. 13)
until the excavation was sufficiently advanced beyond the portal, so
that the effect of the blasting wo\ild not be so severe. The depth
of the cut was reduced from 8 to 6 ft., and the spacing of the holes
in the bench was reduced from 5 to 3 ft. This new arrangement
required much more drilling (4.7 lin. ft. per cu. yd. of excavation
as compared with 2.5 lin. ft. previously used), but was efficacious
in reducing the concussion and the subsequent vibration of adjacent
buildings and breaking of windows. After the excavation had been
carried about 250 ft. beyond the portal, there was little concussion
noticed on the street, and the drilling was brought back to the
32-hole heading. (Fig. 11.)

In the prosecution of this part of the work, the aim was to make
an advance of from 5 to 8 ft. in 2 days. In general, the center
heading and the middle bench were fired on one day, and the upper
and the bottom benches on the next. The advance in the heading
varied from 5 to 8 ft., depending on the character of the rock; the
sides and the benches were taken out about 5 ft. at a time, an extra
shot being occasionally taken out of the sides and benches, so that
the progress would keep up with that of the heading. The work was
done with one mucking and two drilling shifts working as follows:
Mucking gang, 10 A. M. to 7 P. M. ; drilling gangs, 6 A. M. to 2.30 P. M.,
and 4.30 p. M. to 12.30 A. M. The blasting was done before the mucking
gang came on (between 7.00 and 10.00 a. m.), and from 12 m. to
1 p. M., when the mucking gang stopped for lunch.

The best monthly progress in excavation in this tunnel was 100
ft. of full section, or about 3 700 cu. yd. of excavation within neat lines.



358



SUBWAY TUXXEL WORK




SUBWAY TUNXEL WORK



359



Yardage

Total linear teot of drUl holes.
Total poiinda ot 60 J Forclte.
Linear feet ot holee per cublo yard.
[P.ouud8 of .Forclte per cublo jard.




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