Evening star., 1898-01-26

seems to of1er large economy in quantities
and cost without the sacrifice of proper
"The masonry of the design, as described
heretofore, had width of fifty-two feet,
beyond which the sidewalks were located
on brackets. The modification consists in
the removal of the central twenty feet of
this fifty-two feet of width, leaving two
viaducts of masonry each sixteen feet
wide, similar and parallel. The twenty
foot space between them at the roadway
level is designed to be spanned by a floor
system of structural steel and concrete,
resting on the two masonry vtaducts and
supporting the asphalt roadway. This
proposition, while novel, would seem to
be strictly justifiable. 1t would reduce the
cost materially without diminishing the
strength or stability. AS to the architect
ural ethics involved 1t would seem to be
quite as admissible as the method almost
floor system with masonry supports.
"A modification of this suggestion, which
would be Indicated by correct architectural
tasta, would be to increase still further
the open space between the two parallel
viaducts without lessoning their width of
sixteen feet, which would result in dimin-
ishing the length of the projection of the
sidewalk brackets. even reducing them to
the proportions of q cornice. Such
change would not AFFECT the cost substan-
TALLY.
Reasons for the Selection.
'In the selection of the most suitable
from among the submitted designs the
judgment of the Commissioners was that
the masonry type was altogether the best,
provided 1t could be secured at cost not
prohibitive. The principal considerations
leading to this decision were that the pro-
posed bridge, being SO conspicuously To-
Gated on fine residence avenue and in
full view of large area, within which was
the National Geological Park. should be of
monumental character and the masonry
type. above all Others fulfilled this condi-
ton as well as that of suitability.
THE history of metallic viaducts Is one
Of continual outlay for maintenance and
repair, with frequent ending by the re-
placement Of the structure by one of
masonry. The advantage of economy of
first cost in metallic structure is thus
largely Offset by the necessary annual
outlay for its proper preservation, and
where the costs of a masonry and metal
lie viaduct can be brought within the same
class of figures. as In this case. the de-
construction is easily justified.
"A metallic structure progressively de-
teriorates with age; a masonry one, espe-
cially concrete eonea progressively i'm
proves.
THE design of viaduct recommended Is
specified as a masonry one. and it follows
that the cost Of its construction can be
made TO range through wide limits, ac-
cording to the class of masonry selected
and used. The most expensive kind Is, of
course, first-class granite ashlar, but this
is believed to be practically beyond consid-
GRAFTON by reason of its excessive cost in
comparison with other substantially equiva--
lent material 1t would, of course be alb
soluteiy the best, but tie additional quality
secured would be purchased at too high q
PRICE,; as "a comparison of thef estimates
will show. dog = 70. 0fi tss" sHroft ;'as-
Comparison as to Cost. (. -
'"The use of the same class of masonry IN
q nhoon oln nf ctN
stone. results in a substantial reduction of
cost of granite. The result would be desir-
able in every way, were 1t not that the
use of high-class concrete would permit a
much greater possible economy without
sacrifcing the proper qualities to be in
sisted on in the design.
The suggestion of brick masonry has
been duly considered, but 1t Is not appar-
ent that it offers the advantages of con-
crete, while its cost would be somewhat
greater. Its use, in part, in connection
with ashlar. would appear to be the limit
OF its applicability and into the fully con-
sideration of the concrete type 1t need not
enter
Concrete Of a high grade is properly
making for itself an increasingly large
field of application as material of con-
struction. It is believed that it's prepara-
tiOn and use was never better understood
than at present, and that the materials
for It's proper preparation were never more
available. 1t can be substituted, with
proper care, for almost any other class OF
masonry with safety and with agreeable
| results as to the appearance of the COM
| pieted work. 1t can be made to simulate,
| If desired, the highest class of finished
! stone work, or 1t can be prepared as a
| monolithic type which shall possess the
simple dignity of massiveness. 4sE
| 1T is the pronounced characteristic OF
| the design of Mr.. Morrison that it lends
vol fop ,I1 t1n 9th chi mi tn6
to the advantageous use of this material
| This is accounted for by the, relatively
| small amounts of masonry proposed In the
| other designs. so that a decrease In the
cost of the masonry in the latter struc
| lures would make a relatively small de-
crease in the total cost.
| Concrete Type Advised.
1.-THE use of the concrete type.is advised
| primarily as an economical construction
but without intended implication that II
| is a cheap device OF with any reservation
1 as to its structural sufficiency.-,
| "It Is known that in it's construction the
| best intelligence must be enlisted and the
| most careful supervision of the work ex
] ercised, but these are requirements ina
| can be met and are anticipated and al
| lowed for.
IA proper subject of remark In con
| nection with the proposed new, structure
is the existing Woodley Lane bridge. This
| bridge was constructed under peculiar cir
| cumstances at an elevation winch was
| recognized as justif1able only because
| limited funds prevented its. being placed
| higher. AS it now stands 1t Is too low iol
| travel that will Cross the valley and too
| high for a crossiIE OF the creek for trave
| in the valley. It Wall be practically sup
| planted for the former class by the new
| structure and discontinued existence II
| its present position would be serious
| detriment to the fAppearance of the new
bridge. 1t is rec4nmSnded that 1t be re.
moved and rebuiltfat q lower level and al
| point to be selected further up the strean m
| within the limits of the Geological Park
The cost of this sirorss would not exceed
| Attention is invited, to the fact that the
| entire site of the proposed bridge an area
| Of about 275, 600 square feet. Is at this GATE
| the property of the District OF Coiumpla,
| with the exception Of about $4,000 square
| feet of land, consisting of certain lots In
| block 25, Kaloranaa Heights. Condemna-
ton proceedings In relation to these are
| now pending.
ReductlOnssof Cost.
Eve recommend that the concrete design
of Mr.. Morrison be used in the construction
of this bridge. If appropriation therefor be
authorized. We believe 1t should prefer
| ably be used on the general plan as origi-
| nally submitted. but should considerations