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was hoped that the Bowl could be completed in the fall of 1913. In
other words, it was proposed to build a continuous concrete lining,
nowhere more than 4i in. thick, to cover an area measured in acres,
on a new and hurriedly built embankment 27^ ft. high. It was the
opinion of the Committee that, in a structure as important and con-
spicuous as this was bound to be, the procedure proposed would invite
undesirable defects, and that, though it might be possible to compact
the embankment so that unsightly cracks might not occur, it was
preferable to reduce the risk to a minimum. The Committee, there-
fore, though approving the general plan, reported adversely to the
proposed construction of the concrete lining, and recommended a lining,
lifted a few inches above the ground, made up of inverted channel-
shaped slabs, supported by radial girders resting on small pedestals built
in the embankment. It was proposed to make the slabs uniformly
30 in. wide, of the same cross-section, and to lay out the work so that
both slabs and girders should have spans of about 20 ft., and, to the
greatest extent possible, be duplicates of each other. The variation
in the rise of the steps or benches was to be taken care of by the form
of the tops of the radial girders. It was planned to have the very large
number of slabs required cast in advance in a concrete casting yard,
where the concrete work could proceed independently during the
progress of the earthwork, and to erect the pre-cast units very quickly
with a small traveling derrick as fast as the embankment was completed.
To facilitate the construction, and at the same time take care
of the rainfall on the inner lining, the slabs were not to fit each other
closely, but were to be separated by slits at least i in. in width and
were to be tilted to shed water. Rainfall was to be prevented from
accumulating, and was to be allowed to escape directly through the
sand and gravel, as it had always done before in the plateau in which
the structure was to be built. The ability of this material to absorb
rainfall had been proved to the satisfaction of the Committee by sinking
a shaft at the site from the surface of the ground to below the depth
of the playing field, and this shaft had cleared itself of water imme-
diately after every hea"\^ rainfall. To protect the newly made inner



DISCUSSION ON THE YALE BOWL 285

face of the earth structure from being carried down by the drainage, Mr.
it was proposed to cover it with a layer of cinders, about 6 in. thick,
a method found particularly effective in the construction of railroad
embankments.

The Committee obtained estimates on the construction described
from contractors most experienced in such work, and was convinced
that the cost of the completed structure would not be increased mate-
rially by the proposed changes from the original plan.

The recommendations of the Committee were formally adopted;
detailed plans and specifications were prepared and accepted; and a
contract was executed for the earthwork and concrete tunnels, leaving
the slab work for the interior lining to be included in a later contract.
At this stage, however, other counsel prevailed, and the slab and
pedestal plan was abandoned. From the description given in the paper,
it appears, however, that when the time arrived for actually building
the concrete lining on the embankment, notwithstanding the extremely
careful and expensive methods used to compact the fill, it was not
deemed wise to disregard the advice originally given, and the con-
struction of the permanent lining was postponed mitil the danger
of settlement should be known to have passed. It is also to be noted
that the temporary construction finally placed on the embankment
allows the rainfall to pass directly into the underlying sand and gravel
without accumulation, exactly as was proposed in the slab and pedestal
plan.

In view of the final decision, not to build directly on the embank-
ment, it seems unfortunate that so much expense was incurred in com-
pacting the material, as this will now be done by several years of
exposure to the elements.

It is the opinion of the speaker, and iie knows it to be the opinion
of others who have had experience in building railroad embankments,
that the rolling of clean sand and gravel, such as was available for this
work, is of doubtful advantage, and, on the other hand, that the liberal
use of water while the material is being deposited is highly effective.
From the levels reported by the author, it seems to have been demon-
strated that the fill was well compacted, but it does not seem at all
clear that this result was due, to any great extent, to rolling. As
the paper states, the very considerable part of the embankment between
the tunnels was not rolled, and as, in addition to the water applied
while the material was being deposited, the bulk of the fill had been
exposed to a winter of snow and rain, the actual advantage of the
rolling does not seem to have been very conclusively demonstrated.

H. C. Keith,* M. Am. Soc. C. E. — What the speaker is inclined jvir.
to say is not so much in discussion of the paper as an expression of

* New York City.



Keith.



286 DISCUSSION ON THE YALE BOWL

Mr. appreciation of the great idea which Mr. Ferry presented to the world
^^ ' in building the stadium in this form, and in this way, at New Haven.
There are very few places where such a stadium could be built satis-
factorily: the nature of the soil and the location with respect to the
possibilities of drainage were great factors in making this a possibility.
Although it was necessary for the speaker and his associates on
the Board of Consulting Engineers, at one time, to differ from Mr.
Ferry in his recommendations in some details, yet they always felt
that he was deserving of great credit for the plan presented. The
method of construction has also been an important factor in making
the design a success.

It is disappointing that the paper gives no information as to the
cost of the stadium as it is finished to-day; it is hoped that before it
is printed in its final form, such figures will be included. It is well
that the Transactions of the Society should make ample record of this
construction.

Mr. H. F. Dunham,* M. Am. Soc. C. E. (by letter).— The double roll-

un am. -^^^ with frequent disturbance of the material, was helpful in some
degree in making a firm embankment. Experience has shown the
advantage of vibration in solidifying sand and gravel when under pres-
sure. Those who have had occasion to direct the tamping of loose sand
and gravel for railway water tanks and building foundations will be
apt to agree in this. The vibration in all such cases, even when slight,
is more effective than the pressure. This was well illustrated by experi-
ments made a few years ago in New York City by Mr. Alfred O.
Crozier in compacting sand for concrete products. The almost instant
reduction in volume and hardening of the mass that occurred imder
slight vibration in two directions and without any pressure except the
weight of the material itself^was a matter of surprise and interest to
all observers. In the writer's opinion, any easily operated tamping
machine, even if heavy blows are not delivered, woiild be more effective
than the rollers. This view is not to be considered as a criticism of
this excellent paper, which brings distinction to its author.

Mr. Henry C. HiTx.f Assoc. M. Am. Soc. C. E. (by letter). — The writer
has been very much interested in this particularly well written descrip-
tion of an unusual piece of construction. The author has given a
very complete and satisfactory description, full of the data one wants,
of the details of the design and of the construction methods.

The design certainly appears to be very successful. The "bowl"
shape is an outdoor adaptation of old principles of auditorium design,
and undoubtedly provides the most ideal seating scheme, as well as
being architecturally beautiful. It is strange that it has not been

* New York City.
t Seattle, Wash.



Hitt



DISCUSSION OX THE YALE BOWL 289

used more frequently with other stadia. The slate-colored concrete, Mr.

. Mitt

with a trim of the inner retaining wall and the tunnel portals in natural
color, the comfortable seats, the beautiful elliptical shape, and the
careful orientation as to the afternoon siui, must all go to make the
structure a credit to every one responsible.

The author, in comparing the Bowl with other modern stadia, states
that it is probably the cheapest per sitting vmit. In this, however, he
is in error, as the Tacoma Stadium, which the Bowl resembles in some
ways, has cost, completely equipped, only about 85% of what the
Bowl, in its unfinished condition, with a portion of the seats temporary,
and the dressing rooms not built, is reported by the author to have cost,
per unit of seating capacity.

Thus far, the total cost, of every kind, of the Tacoma structure,
built in 1910, has been $147 000, and an estimate of the seating capacity,
based on the same assumptions as used by the author, is 23 784, giving
a unit cost of $6.20. The architects claim a seating capacity of 32 000,
and more than 35 000 people have actually occupied the stadium at
one time, with none of them on the field, but part of them standing.

The site has also a reserve capacity of about 15 000, as the sodded
terraces rise for 43 ft. above the top of the seats around more than
half the perimeter, at a proper slope for future seating as the needs
of the rapidly growing city demand it. The addition of these seats
would materially cut down the unit cost of the whole.

The two structures were designed to fill widely diilerent conditions,
but are similar in the result. The fields are of practically the same
area, but where the Yale Bowl was designed strictly for football and
seating capacity, with few or no limiting conditions, the site of the
Tacoma Stadium was limited, and the field had to be adapted for the
general use of the people and the adjoining High School, for track
work, football, baseball, pageants, concerts, or political meetings. This
made a complicated problem, which was most happily solved.

The seating scheme is similar to one end only of the Yale structure,
with every occupant able to see the whole field, and most, if not all,
the audience. At Tacoma, however, the designers had a natural
location, of which they took the fullest advantage. The site is on a
promontory in the very heart of the city, with the playing field 140
ft. above the harbor. From the Stadium seats one gets a view probably
not equalled by that from any similar structure. Spread before the
spectator is a magnificent sweep of busy Tacoma Harbor, green hills,
and snow-clad mountains. The Stadium is flanked on each side by
beautiful buildings rising above the seats, on one side the Stadium
High School and on the other the State Historical Museum.

Although the site was naturally somewhat adapted to the purpose,
there was a very large quantity of excavation, more per unit of seating



390 DTSCUSSIOX ox THE YALE BOWL

Mr. capacity than with the Yale Bowl, and about two-thirds of it proved
■^'"' to be very hard cemented gravel. All the seats are carried on columns
and radial girders about 20 ft. apart, the risers of the seats, 3^ in.
thick, reinforced with a structural frame carrying the seat load between
the girders. Part of the columns, at the outer end, are carried on
piling, and part of the field at this end is a fill of 147 ft., but there
has been no trouble from settlement.

Twenty-eight arc-light projectors are placed around the field above
the seats, and twelve more are suspended by cables, high above the
field, affording ample light for evening performances. The acoustics
are very fine, and concerts have been entirely successful. The stadium
is fully equipped with dressing rooms, and comfort stations for the
spectators.

The principal quantities were, approximately:

Earthwork 185 000 cu. yd.

Reinforced concrete 10 000 cu. yd.

Reinforcing steel 160 tons, plus

Clinton fabric 130 000 sq. ft.

Area of field 3.6 acres

The Tacoma Stadium was built by the Tacoma School Board, Mr.
Frederick Heath having been the architect, and Mr. L. A. Nicholson
the engineer.



Lynch



Mr. Alexander S. Lynch,* Assoc. M. Am. Soc. C. E. (by letter). — Mr.

Ferry states that Sherardized bolts were first used to fasten the seats
to the concrete and then abandoned for the bronze bolts, as originally
planned. He does not state why this change was made, other than
that the Sherardized bolts were unsatisfactory. The writer would like
to know why they were unsatisfactory.

Mr. Atwood states that the greatest movement in the high walls
was i in. A recent examination of the walls shows that the movement
in one was less than i in., and in the other it was | in., making a
noticeable and very unsightly crack. The writer would like to ask if
the soil under both walls was the same, or if there was a difference in
the design of the walls.

The final cost of the bowl as given by Mr. Atwood is $750 000.
Does this include the cost of the 23 000 seats erected for the Harvard
games of 1914 and 1916, and subsequently removed?

There seems to have been no apparent reason for applying Trus-Con
floor hardener to the aisles. Mr. Atwood states that no wear is per-
ceptible. Neither is any wear perceptible in the floors of the tunnels,
although the traffic there is much greater. There was no more reason
for applying Trus-Con hardener to the aisles of the Bowl than for apply-

* West Haven, Conn.



DISCUSSION ON THE YALE BOWL 291

ing it to the concrete sidewalk. The only effect now noticeable is that Mr.
the hardener was improperly applied, leaving many of the blocks a ^^°^^-
dirty, rusty brown, unpleasant to look at, and spoiling the general soft
gray tone produced by the use of lampblack.

After reading Mr. Atwood's discussion, one is led to wonder why
Mr. Ferry should have submitted a paper on the Bowl. Mr. Atwood
gives "much credit" to the Committee of Consulting Engineers, which
assisted in getting the work "properly started", and to others, but
nowhere does he mention Mr. Ferry, except to refer to a paper read by
him before the Connecticut Society of Civil Engineers. The writer,
like hundreds of other engineers throughout the country, was under
the impression that Mr. Ferry had not only designed the Bowl, but that
he had in truth created "something new under the sun." The writer
still holds that belief.

Charles A. Ferry,* M. Am. Soc. C. E. (by letter). — In reference Mr.
to the cost of the Bowl, Mr. Atwood states: "when finally completed ^^^'
the cost will be about $750 000, or approximately $12.30 per seat." He
does not give the details of this estimate, further than to state the dif-
ferent pieces of work required to complete the structure. Of these, the
plans for the "permanent toilets" and the "permanent fence" have not
been finally settled, so far as the writer knows; consequently, the cost
might be any sum that Mr. Atwood chose to assume. It is question-
able whether the cost of a fence enclosing the Bowl should be charged
to that structure any more than that of the land on which it is built.

The sum paid to the contractor was a little less than $448 000. The
plans for the Bowl were radically changed after the work was well
advanced, as mentioned by Mr. French, thereby necessitating much
extra work, as well as extra prices for considerable work already under
contract. This also included a large sum for grading, which, although
desirable in the development of the plans for the athletic field, was not
necessary in the construction of the Bowl itself. It also included the
cost of the temporary dressing rooms and the erection and removal of
the temporary toilets and extra temporary seats for the Yale-Harvard
game of 1914. If the extra temporary seats built for the Yale-Harvard
games are to be included in the cost of the Bowl, as apparently they
have been in Mr. Atwood's estimate, then, in all fairness, their num-
ber should be included in computing the cost per seat. On this basis,
that cost would be only about $9.70 per seat, even at the extravagant
estimate of $750 000.

The writer is confident that if the Bowl had been built as origi-
nally planned by him, the cost of the completed structure, including
that of permanent toilets, which was not included in the original esti-



New Haven, Conn.



293 DISCUSSION ON THE YALE BOWL

Mr. mate, would not have exceeded $450 000, or about $7.40 per seat, as
^"^' the contractor's bid, based on the engineer's list of quantities, was
lower than the writer's estimate made on the same basis.

This price compares favorably with that quoted by Mr. Hitt for
the Tacoma Stadium, namely, $6.20, when the relative sizes of the
two structures are taken into account, as the price per seat in-
creases with the increase in size of the structure, regardless of the
materials used.

Judging from Fig. 14, illustrating Mr. Hitt's admirable discussion,
benches are not provided in the Tacoma Stadium, the spectators sit-
ting directly on the concrete, as in the Harvard and Princeton Stadia.
The permanent benches for the Bowl cost about $0.93 per seat, includ-
ing painting.

The cost of the Tacoma Stadium would seem to confirm the writer's
opinion that large stands constructed in the manner used by him in
building the Bowl are more economical than those built by any other
method hitherto used.

The history of this structure well illustrates the truth of the old
adage that "too many cooks spoil the broth." Only, in this case, the
"broth" (Bowl) was not spoiled, but the "high cost of living" (build-
ing) was very largely increased.

The writer is exceedingly skeptical regarding the utility of Mr.
Atwood's method of consolidating the embankment, as described by
him. No levels were taken on the embankment at the time, and, as
there were no near-by permanent objects with which to compare the
height of the embankment, the measurement of the settlement was
dependent on the imagination of the observer. To believe that a given
quantity of water, discharged at the bottom of small holes, 2 or 3 ft.
deep and about 8 ft. apart (assuming that such holes existed in the
saturated sand after the pipes or bars were withdrawn), would have
any more effect in consolidating material several feet below the bottom
of the holes, than an equal quantity percolating uniformly through
the full depth of the sand, requires more credulity than is possessed
by the writer.

As for the effect on the upper portion of the embankment by jet-
ting water down into it, the writer is positive that the result was just
the opposite of that desired. The water injected into the embankment
washed out the finer particles of sand and deposited them in flat,
volcano-like cones around the pipe, and the coarser particles were left
in as loose a condition as it was possible to make them by the boiling
action of the water escaping upward around the pipe. Only about
one-half the circumference of the Bowl was treated by this novel
method of "consolidating" material; and the opinion that this work
was not only useless, but worse, would appear to be substantiated by



DISCUSSION ON THE TALE BOWL 393

the fact that the benches which showed the greatest subsequent settle- Mr.
ment were in the sections thus treated, and the points of least settle-
ment were in those portions which did not receive the "water cure",
although the latter were on the west side of the Bowl where the depth
of fill, between tunnels, was greatest, the tunnels on the east side
being largely in cut.

Mr. Atwood states that:

"In the concrete facing inside the Bowl, the horizontal arching
action was not made use of, dependence being placed on the interior
retaining wall to care for any possible tendency of the blocks to slide
down hill."

The writer has never had any fears that the concrete blocks would
slide down hill, particularly those near the foot of the incline, where
the slope is only about 1 on 4, unless pushed down by those near the
top, where it is about 1 on 2*. If, however, there ever should be any
such tendency to slide, he has much more faith in the resistance due
to the arch action than in that of the inner retaining wall, for the con-
crete steps abut against the thin lip of the gutter formed in the top of
this wall, and, although the lip is reinforced, the pressure required to
shear it off is, probably, only a small fraction of that which would be
required to crush or buckle the concrete facing under arch action. At
the present time, 2i years after the laying of the concrete on the lower
part of the slope, there are no indications that there has been any slid-
ing of the blocks down hill.

The experience of the past 2 years indicates the wisdom of the
Committee in abandoning the plan for an open concrete facing raised
above the embankment, as described by Mr. French, and in re-adopting
the plan for a tight facing laid directly on the earth, as recommended
by the Advisory Engineer, Mr. Williams.

Although the material of which the embankment is composed is
very porous and readily absorbs the water from an ordinary rainstorm,
it does not take care of that from heavy downpours, such as are likely
to occur several times a year. Thus far, there has not been much
trouble from the gullying of the inner face of the embankment, as
the runs between the seats are in contact with the ground, thus forming
water-breaks every 30 in. Nevertheless, after a very heavy rainstorm,
the care-takers are obliged to shovel sand from the runs and fill
up the gullies which have formed between them. If gullies, 3 or 4
in. in depth, will form in one storm when there are water-breaks
every 30 in., it is reasonable to suppose that serious ones, such as
might undermine the concrete footings, would form in a period of
a few years when the water had an unobstructed run of 150 ft., even
though the slope was covered with a layer of cinders.



294 DISCUSSION ON THE YALE BOWL

Mr. The principal point in controversy between the writer and the

^®"^' engineers consulted by the Committee previous to the adoption of
the plans, was whether the material in the embankment could be
consolidated so that there would be no settlement which would be
likely to cause injurious cracking of the concrete facing. The writer's
20 years' experience in back-filling sewer trenches and, particularly,
in the construction of an embankment on which to build a slow
sand filter, led him to believe that it was possible, by the use of water,
supplemented by thorough rolling, to construct a stable one for the
Bowl. For the filter foundation, the maximum depth of the fill was
about 16 ft. The material composing the fill was a mixture of clayey
hardpan and a very fine sand saturated with water — practically quick-
sand. These materials were mixed roughly by working both borrow-
pits at the same time, but there was no special effort to secure a
thorough mix by harrowing. No water was used, except such as
was contained in the quicksand and from occasional rains. The
material was leveled off in layers about 8 in. in thickness, and was
thoroughly rolled with a grooved roller; a smooth roller was not
used. The fill was completed late in the fall. Benches were estab-
lished at various points, after which an embankment, about 18 in.
high, was built around the edges of the fill, and the area was flooded
with water, the pond being maintained throughout the winter. In
the spring, the water was drawn off, the benches were tested, and it
was found that the maximum settlement was about I in., a little
better result than was obtained at the Bowl, although, at the latter,
the depth of fill was nearly twice as great as at the filter foundation.

The argument advanced by Mr. French, that because "the bulk
of the fill had been exposed to a winter of snow and rain, the actual
advantage of the rolling does not seem to have been conclusively
demonstrated," does not apply to the section of the embankment,
about 300 ft. in length, in the vicinity of the proposed large gate-house.

A portion of this fill, that immediately back of the retaining wall,
is more than 40 ft. in depth (the deepest fill on the work) and all of it,
from foundation to promenade, was deposited in the 9 weeks between
April 4th and June 6th. The material was consolidated only by the use
of water and rolling, as specified for the remainder of the work, the
assistance rendered by Nature, in the form of snow and rain, being
negligible, as the water secured in this way was insignificant in quan-



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