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outside of the Bowl, with hose connections at frequent intervals. The
water from the wells was pumped by a single-acting, triplex pump,
operated by an electric motor. The contractor was required to furnish
at least 150 gal. of water per min., and this quantity was delivered
continuously, day and night, including Sundays and holidays, while
the embankment was under construction. A connection was also made
with the mains of the New Haven Water Company, in order to insure
a constant supply in case of a failure of the wells or a break down of
the machinery.

As the drag-line scrapers left the inner face of the slope in a very
irregular condition — a series of deep gullies and sharp ridges — the
contractor devised a leveling scraper for smoothing up the work. This



THE YALE BOWL 275

consisted of a frame, about 6 ft. square, of 12 by 12-in. timbers, the
front faces of which were shod with steel plates. This frame was
attached to the drag-line by a bridle, and was drawn up the slope in
the same manner as the excavating scrapers. The final trimming of
the slope was done by hand shoveling.

Two mixers were used for supplying concrete for the tunnels. For
the footings, there was a portable, i-yd., gasoline mixer at the inner
portal of each tunnel. This delivered its material into cars running
on a track laid between the footings, from which the concrete could be
dumped into the forms on either side as desired. An electrically
operated f-yd. mixer near the center of the field was used for mixing
the concrete for the portion of the tunnels above the footings. The
concrete was conveyed on cars running on an industrial railway track
laid on the ground from this mixer to a point near the inner portal
of the tunnels, then up an inclined trestle to their top and then on
timbers laid on the side forms. From the mixer to the foot of the
incline the cars were hauled by a horse, and for the remainder of the
distance by a hoisting engine outside the Bowl.

For building the outside retaining wall and the smaller gate-house
walls, there were two i-yd. mixers on an elevated trestle built on the
site of the gate-house. These delivered the concrete into bottom, side-
dump cars running on an industrial railway laid on top of the wall
forms. For the large gate-house walls, a mixing plant was established
near the wall, and the concrete was delivered into a 120-ft. elevator,
from which it was distributed by chutes. The same plant also made
the concrete for the inner retaining wall and the facing steps. For
this work the concrete was delivered by the chutes into the bottom,
side-dump cars running on a portable track laid just above the iinier
portals of the tunnels ; from them it was distributed, by portable chutes
laid on the ground, directly into the forms, the slope of the bank being
steep enough to cause the concrete to flow in the chutes. The greatest
distance through which concrete was carried by the chutes, in a single
run, was about 250 ft.

For handling sand and stone at the two main mixing plants, ele-
vated bins were constructed so that cars or trucks could be run on
top of them and deliver material without shoveling. Chutes at the
bottom of the bins delivered material into cars which were divided by
partitions to hold the required quantity of each ingredient for one



276 THE YALE BOWL

batch. From the ears the materials were dumped directly into the
mixer.

All the sand for the work was obtained at the site. Though an
abundance of gravel, of a size suitable for the concrete, was fo\ind in
the excavation, only a small quantity of it was used in some of the
footings, as it contained a considerable proportion of sandstone pebbles
which it was feared would absorb moisture and disintegrate under the
action of frost if exposed to the elements. Most of the stone used was
crushed trap rock. This was brought from a quarry about 2J miles
distant by two motor trucks: a 5-ton truck which not only carried its
own load but also hauled 3 tons in a trailer; and a 3-ton truck. The
price paid for hauling the stone was 27 cents per ton.

The cement used in the work was furnished by the contractor, but
was paid for as a separate item, thereby enabling the engineer to change
the proportions of the ingredients in the concrete, as seemed desirable,
without causing any dispute as to the quantity used. The cement was
all tested at the mill by agents of testing laboratories.

Comparison with Other Stadia.

The Bowl is believed to have the largest seating capacity of any
structure of the kind in existence, and to have been exceeded by only
one of ancient times — the Circus Maximus of Rome, which is stated
to have seated 380 000 persons. Statements regarding the capacity of
the Roman Colosseum, the most widely known of the ancient amphi-
theaters, vary widely from 45 000 to 100 000. It is stated that in the
ancient amphitheaters only the classes were provided with seats, the
masses being obliged to stand.

With the seats removed, the Bowl could accommodate comfortably
a standing audience of about 125 000. The Athens Stadium seated
50 000 ; the stadium of the College of the City of New York seats about
10 000 ; the Syracuse and Tacoma Stadia each accommodate about
20 000; the Boston baseball stands, 24 000; the double-deck stands at
the New York Polo Grounds, about 28 000 ; the Harvard Stadium, as
first constructed, seated 23 000, but, with additions and with tem-
porary seats at the open end, it can accommodate about 45 000 ; the
new Princeton Stadium seats about 41 500; and the Bowl about 61 000.

Though the Bowl is the largest of the modern stands, it is also,
probably, the cheapest per sitting. Though the actual cost of other



THE YALE BOWL 277

stands is not accurately known, the contract price, as reported in
engineering and other journals, gives the average cost per sitting as
ranging from about $36.00 for the stadium of the College of the City
of New York down to about $8.50 for the Princeton Stadium. The
cost per sitting for the Bowl, as constructed, including the grading
of the grounds around it, was about $7.35. The cheapness of the Bowl
was partly due to the exceptionally favorable conditions at the site
for building this kind of a structure. This was a level plain elevated
about 40 ft. above a marsh from which it was separated by a steep
bluff, thus affording perfect drainage at a minimum of expense. The
material was clean sand and gravel extending to an unknown depth,
easy to handle, and ideal for making a solid embankment.

Previous to the building of the Bowl, the materials used in the
construction of grand-stands were wood, steel, reinforced concrete,
or a combination of the two latter, and, in the case of ancient struc-
tures, masonry. Though wood is a suitable material for stands of
small size, it is entirely unsuited for large ones, owing to rapid
deterioration when exposed to the weather and liability to destruction
by fire. Though monumental structures of masonry, like the Roman
Colosseum, were possible with the slave labor available in the first
centuries of the Christian era, it would be impracticable to finance
such an undertaking at the present time. Steel and reinforced con-
crete are, from an engineering standpoint, more practical building
materials for structures of this kind.

Maintenance charges are an important factor to be considered in
planning for a steel stand of large size. Whether temperature changes
and frost action will injuriously affect skeleton structures of the size
of the large modern stadia, when built of reinforced concrete, either
alone or in combination with external steel, is an interesting question
yet to be answered. Apparently, the only portions of the Bowl which
will require material expense for maintenance are the benches, as the
remainder of the structure is practically a portion of the earth's
crust — a low hill surrounding a small valley.

One advantage of this form of construction, besides its cheapness,
is the facility with which the plastic materials, earth and concrete,
may be adapted to the formation of curved shapes, thus, without any
material expense, permitting of curved instead of straight sides, which
were such an objectionable feature of the old wooden stands at Yale.



278 THE YALE BOWL

Another advantage is that a stand can be increased in size without
materially affecting any part of the work already done. By building a
balcony over the promenade and the portion of the seats above the
tunnel portals, the seating capacity of the Bowl can be increased to
about 100 000 without affecting any portion of the structure other than
by the removal and replacing of a few blocks of concrete to permit the
building of proper footings for columns, the embankment being
sufficiently stable for the support of the additional structure.

With nearly 61 000 seats for spectators provided, it was thought the
stand would be large enough to meet any possible demand for accom-
modations from those interested in football, but when the time limit
expired for the receipt of applications for tickets for the first game in
the Bowl — Yale vs. Harvard in 1914 — it was found that more than
80 000 had been received. To meet this demand, so far as possible,
extra seats were erected over the promenade, so that the number of
people who witnessed that game was probably a little more than 70 000.
In spite of this vast number, in 12 min. from the close of the game, the
Bowl was practically empty of people, and this time might have been
shortened by about 5 min. had not the spectators tarried to witness the
celebration of the victory, on the gridiron, by the partisans of the win-
ning team. Although the Bowl was emptied in such a short time, there
was no congestion at any point except in the aisles, as the capacity of
the tunnels to handle the crowd was greater than that of the aisles, and
the thirty-two tunnels distributed the crowd over such a large area, the
inner circumference of which was a little more than i mile, the dis-
tance around the outside of the Bowl, that there was plenty of room for
the free movement of the people.

Adaptation for Other Purposes.

Although the Bowl was built for football alone, its remarkable
acoustic properties render it admirably fitted for the production of
dramatic events on a large scale, and two such have already been held
there with pronounced success : the Greek play, "Iphigenia in Taurus",
given by Mr. Granville Barker under the auspices of the Yale Dramatic
Association, and the opera "Die Walkiire", by the Metropolitan Opera
Company, under the auspices of the Yale School of Music. For these
performances, the stage was erected near the center of the field, and a



THE YALE BOWL 379

section of about 25 000 seats was set apart for the spectators at one end
of the amphitheater.

To celebrate the two-hundredth anniversary of the removal of Yale
College to 'New Haven, a pageant is now being prepared in which it is
expected that about 8 000 performers will participate.

Under favorable atmospheric conditions, when there are only a few
people in the Bowl, a whisper spoken at the center of the field can be
distinctly heard at the tunnel portals; and a conversation, in an ordi-
nary tone of voice, can be carried on between persons stationed on op-
posite sides of the amphitheater. At the performances mentioned, even
the softest passages could be plainly heard in the most remote seats
reserved for spectators. With the seats removed, a person with a good
voice and accustomed to public speaking could, undoubtedly, address
an audience of 125 000 and be heard distinctly by every one.

The following are some of the principal items of construction:

Earthwork 331 000 cu. yd.

Mass concrete 16 000 " "

Concrete facing Ill 000 sq. ft.

Wood facing 145 000 " "

Granolithic pavement 35 000 " "

Cement 26 000 bbl.

Steel for reinforcement 482 tons.

Wood benches 18 miles.

Turf laid 161 000 sq. ft.

Sewers 6 400 lin. ft.

Water mains 4 700 " "

Area covered by structure, about 12^ acres.

The Bowl was built by the Yale Committee of Twenty-one, Incor-
porated, Mr. Thomas DeWitt Cuyler, Chairman, with Mr. David "Dag-
gett, Chairman of the Structures Committee. Edward G. Williams,
M. Am. Soc. C. E., was Advisory Engineer, and Mr. Donn Barber,
Consulting Architect. The writer was the Designer and Engineer
in charge of construction. Mr. Joseph H. Mulvey was Chief Inspector.
James B. French, M. Am. Soc. C. E., served as Consulting Engineer
for a few months at the beginning of the work, and Thomas C.
Atwood, M. Am. Soc. C. E., as Construction Manager for a few months
at the end. The Sperry Engineering Company, of New Haven, Conn.,
was the contractor for the whole work.



280 DISCUSSION ox THE YALE BOWL

DISCUS SION



Mr. Thomas C. Atwood,* M. Am. Soc. C. E. — As has been staled in the

Atwood. p^pgj,^ ^j^g Yale Bowl is the largest structure of its kind which has
ever been built. When compared with the designs for other stadia
proposed for this place, its simplicity and effectiveness at once com-
mand attention. The character of the structure, essentially of earth-
work, ensures its permanence; and its safety from fire and accident
is beyond question.

The original sketches called for a structure, the estimated cost of
which was somewhat less than $400 000, but the several engineers and
architects engaged on the work have advised certain changes, affecting
the appearance and permanence of the structure, which have nearly
doubled this cost.

The paper is hardly fair to other stadia in stating the cost of the
Bowl as $7.35 per seat, this being the cost in its present incomplete
condition. When finally completed the cost will be about $750 000, or
approximately $12.30 per seat, or considerably more than the cost of
the Princeton Stadium. This includes the cost of completing the con-
crete lining of the Bowl and placing the permanent seats, the gate-
houses, permanent toilet facilities, and permanent fence. The Prince-
ton Stadium is not fully completed,, the wooden seats being lacking,
but the final cost will probably not be more than $10 per seat. Of
course, the difference in size must be taken into account, and a larger
structure of the Princeton type would undoubtedly cost more per seat.
All things considered, it is probable that the Bowl is the more eco-
nomical structure for the location, which is ideal for its type, and for
the size demanded.

There is no doubt that the shape of the Bowl, with its curved sides,
is far better than the regular stadium U-shape with straight sides.
It is this horizontal curve of the sides, rather than the vertical curve
produced by making the height of each riser uniformly greater than
that of the one next below it, which enables the rise per seat to be small,
the straight-sided structures requiring more rise in order that spec-
tators may see all parts of the field. The importance of this is seen
when it is realized that in the Bowl only 20 000 of the seats are enclosed
between the goal lines extended, and that more than 40 000 are at the
ends, back of the goal lines. At Princeton about 16 000 seats lie
between the goal lines, and 25 000 are back of them, but only one end
is enclosed, the other being open.

Of the problems in connection with the Bowl, few were of less
interest than the eleventh-hour proposition to put in a track and pro-
vide a 220-yd. straight-away course by tunneling at one end. Careful

* New Haven, Conn.



DISCUSSION ON THE YALE BOWL 281

estimates showed that this would involve such heavy construction that Mr.
the cost would be about $50 000, and would detract considerably from "°° '
the appearance of the Bowl. Experience with such tunnels, as at
Syracuse, N. Y., has shown that the running conditions are not satis-
factory ; and, as the Committee had plenty of land available, and as an
ideal track on open ground, together with a permanent stand to seat
10 000 people — as many as are likely to attend the intercollegiate track
events — would cost little if any more than the tunnel, it was decided
to complete the Bowl as planned and build a track and stand later.

Referring to the general construction : when the speaker was placed
in charge, on January 1st, 1914, approximately one-third of the work
had been completed, and the embankment had reached the top of most
of the timnels. As noted in the paper, the rolling could not be carried
on between the tunnels, and it seemed improbable that the bank had
been thoroughly consolidated at all points, so the top of the bank was
leveled up, divided into sections, and flooded, holes being drilled dowia
through it at the same time by iron bars or water jets about 8 ft. apart,
on centers, both ways. At some points no settlement could be ob-
served, but at others there was considerable. On this uniformly com-
pacted base the remainder of the bank was built, as described in the
paper, and with gratifying results.

The whole settlement of the completed bank is not shown by the
•bench-marks noted in the paper, as these were not set until the bank
had been completed for nearly 2 months, but there is no doubt that
the settlement was very small compared with that found in other care-
fully built banks, such as those under aqueducts.

The water pipe entering the Bowl was carried through the main
tunnel in a small trench in the concrete floor, so that a break coiild
not affect the foundations of this tunnel and the embankment.

The turf strips, noted as being placed in the outside loam slope,
were very successful in preventing deep wash, as was showTi by a tor-
rential rain which occurred before the seeded area had started to grow,
the water in no case getting under the sod, and no gullies more than
3 in. deep being formed.

The high reinforced concrete retaining wall mentioned has per-
formed its work well, a movement outward at the top of little more
than i in. being the greatest noted, or corresponding to a settlement at
the toe of the wall of only about J in. Relative to this matter, it may
be mentioned that claim for royalty on account of the Bone patent has
been made within the past year, and the speaker has done considerable
work in investigating this, with the aid of searches made in the
Library of the Society, and has some references to walls, built before
the date of the patent, which are not included in the summary of
this subject contained in Engineering News.



282 DISCUSSION ON THE YALE BOWL

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 lampblack placed in the mortar for the top of the facing blocks
aided materially in giving them uniformity of color, as the sand used
contained uncertain quantities of iron which caused some of the con-
crete to have a pinkish hue.

The aisles were given a top dressing of Trus-Con floor hardener,
and no wear is yet perceptible ; but it is difficult to say whether or not
this is due to the hardener. This hardener should be applied with
care by skilled men, as a few blocks, which apparently got an overdose,
have turned rusty.

The inner retaining wall and the tunnel portals inside the Bowl
were originally planned to have pipe-rail fences, but this was changed
to heavy concrete parapet walls, at a considerable saving in cost and
with a decided improvement in the appearance of the Bowl, the general
idea of massive simplicity being carried out more fully.

The design of the permanent seats was another interesting problem.
As finally worked out by Mr. Everard Thompson, Assistant Secretary
of the Committee, and the speaker, the seat was placed on the edge of
the step and supported on a steel bracket or standard which allows full
play for wind and water, so that the structure can be cleaned with com-
parative ease.

The lumber for these seats was selected with great care. It was
desirable to use edge grain lumber, and investigation showed that this
could be obtained in only three woods, Douglas fir, redwood, and
Western hemlock and Noble fir classed together. As redwood is likely
to stain clothing when wet, and Western hemlock could not be obtained
in sufficient quantities, Douglas fir was chosen.

Time was of great importance, and some doubts were expressed as
to the possibility of getting the lumber in the 3 months available. The
order was given by the speaker on August ISth, and the first carload
arrived on September 29th, just 6 weeks later. When the order was
given, the lumber was in the log. It was sawed, kiln-dried, planed, and
shipped within 2 weeks, and was 4 weeks on the road. The kiln-drying,
in this case, was preferred to open-air drying, as it boiled out the pitch
pockets in the fir. All the lumber is vertical grain, clear and free from
knots or other defects, except an occasional pitch pocket.

Another interesting matter was the design of the playing field. The
imderlying sand was so porous that a stream from a 2-in. hose would
all disappear within 2 or 3 ft. of the end of the hose, so the problem was
to retain moisture enough to prevent the grass from burning out, and
yet have a field that would dry quickly after a rain. This was accom-
jilished by using 18 in. of black loam and by crowning the field 1 ft.,
the cross-section consisting of two very flat curves, convex upward.



DISCUSSION ON THE YALE BOWL 383

joined by a sharper curve at the center of the field. The scheme has Mr.

1 J £ ^.^ Atwood.

worked periectly.

The summary of items of construction given is for the Bowl in its
present state, and, of course, many of these will be changed when the
work is completed.

In order to assist any one desirous of obtaining further information,
the following bibliography of articles on the Bowl, all of which are
illustrated, is given:

Engineering Record, Unsigned articles in March and ]!Tovember,

1914.
Engineering News, Article by the speaker, IsTovember 12th, 1914.
Yale Alum7ii WeeJdy, Article by the speaker, November 27th, 1914.
Proceedings, Connecticut Society of Civil Engineers for 1915.

Paper by the author.
Journal, Boston Society of Civil Engineers, June, 1916. Paper
by the speaker.

Much credit is due to the Committee of Consulting Engineers which
assisted in getting the work properly started. This Committee con-
sisted of Professor John C. Tracy, of Sheffield Scientific School, and
IT. C. Keith and James B. French, Members, Am. Soc. C. E. Later,
Mr. French was appointed Consulting Engineer in charge of the design
and construction of the work, and the first contract was prepared under
his direction.

The credit for carrying on the remainder of the work is largely due
to Edward G. Williams, M. Am. Soc. C. E., who served his Alma Mater
without pay in the capacity of Advisory Engineer, and by his wise
advice and careful supervision brought the work to a successful con-
clusion. The architectural features of the Bowl were designed by the
Consulting Architect, Mr. Donn Barber, of New York City, and are
exceptionally effective.

The three contracts covering the work described were finally con-
cluded early in 1915. The speaker, however, was retained by the
Committee to carry on the engineering work, and contracts were pre-
pared covering the completion of the seating structure, permanent
toilet buildings, and permanent fences, in expectation of proceeding
soon with this construction. This expectation was abandoned in the
spring of 1916, and the only work now being done is the construction
of some 17 000 temporary seats for the Yale-Harvard game, on Novem-
ber 25th, 1916. This will make the total seating capacity of the Bowl
on that date 77 189.

J. B. French,* M. Am. Soc. C. E. — The speaker can most prop- Mr.
erly speak for those who advised against building the concrete ^^^'^ '
facing directly on the embankment. Professor John C. Tracy, of

* New York City.



284 DISCUSSION ON THE YALE BOWL

Mr. the Yale Faculty, H. C. Keith, M. Am. Soc. C. E., and the speaker
French. ^^^^ asked to report on this question in November, 1912. Plans
submitted to this Committee at that time were materially dif-
ferent from those followed in the construction. As described in
the papers then submitted, the surface of the inner slope was to
be cut into steps and faced with concrete 4A in. in thickness,
laid directly on the sand, in the same manner as concrete curbs and
sidewalks are built. No steel reinforcement was proposed, and all
drainage was to be carried from the top of the embankment down over
all the steps to the level of the playing field. At this time, also, it



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