Evening star. [volume] (Washington, D.C.) 1854-1972, 1903-06-27
THE PLANS COMPLETE
Preliminaries Ifor Construc-
tion Of Highway Bridge.
PROPOSALS INVITED
SUCCESSFUL BIDDER TO BEGIN
WORK WITHIN THIRTY DAYS.
Structure to Consist Of Two Abutments,
Twelve Piers and Spans Con-
Meeting the Same.
PROPOSALS INVITED

SOl. AlleH, SOfpS Oh ENSlHccHo, IA ShoA6S
of the Improvement of the Potomac river,
has completed all the preliminary arrange
ments for the construction of the highway
bridge across the river In pursuance OF the
act of Congress approved February II, 1901,
as amended by the act approved July i,
1902. He has invited proposals for the con-
struction of the bridge and will open them
July % Detailed and comprehensive spec
ifications in regard to the work have been
supplied to the prospective bidders and
every preparation has been made to secure
a structure which will be an ornament and
a credit to the city AS usual in such
cases, the United States reserves the right
to reject any and all bids and to waive any
informality in the bids. The successful bid
der will be required to commence work I'M
der the contract within thirty days after
notification of its approval, and to prose-
cute the work with faithfulness and
energy so as to complete it on or before
February 1, 1905 Col. Allen considers the
period Stated as sufficient for the COM
pletion of the work by a contractor having
the necessary plant, capital and experience,
unless extraordinary and unforeseen conol-
tons supervene
The complete work contemplated under
the app, owed project is the construction OF
a highway bridge across the Potomac with
approaches on the Washington and Vir-
GINA VI lUe river anu, dS pau VI liz
Washington approach, short bridge
across the outlet Of the tidal reservoir IN
Potomac Park. The specifications furnish
ed bidders relate only to the bridge over
the main river, consisting of two abutmentS,
twelve piers and the spans connecting the
same. The limit of cost of the projected
work for which contract will be made is
$685. 900.
Location of the Structure.
The bridge will be located about 1 ,250 feet
above the Long bridge and will extend
from Potomac Park, on the northeast shore
of the river, to a point 26O feet from Alex
ander's Island, on the southwest shore of
the river. The width, at ordinary high tide,
of the river at the proposed site is 2.s26 feet
and the existing depths at low tide range
from two feet two inches on the shoal near
Potomac Park to twenty-three feet six
inches in the dredged channel. Borlngs
taken on the line of the proposed bridge
show the strata to be mud, sand. gravel
and clay of varying thicknesses, with an
underlying floor of solid rock at depths
of from 1O1 to III feet below low tide
1t is explained by Col Allen that while
the specifications refer more particularly to
a through truss bridge, with horizontal
draw span, bidders are invited to submit
their own designs for fithe bridge, being
limited only by the specifications for ma
terials and workmanship and by the gen
eral conditions, general dimensions, clear
ances. etc, specified. Among the general
conditions prescribed is that the bridge
shall be a steel-truss structure, 1865 feet
in length between end pins, and shall con-
sist of eleven fixed spans and one draw
span, supported by twelve piers and two
abutments of concrete and granite ma
sonry, all with concrete and pile founda-
lions. The first span from the Washington
end Is to extend over Potomac Park 100
feet, in order to leave, space for a drive
and walk on the shoreIof the river under
the bridge
Roadway Forty Feet Wide.
The bridge will have roadway forty
feet wide between curbs, and two sidewalks
each eight feet wide. Onpthe outer side
of each sidewalk will be an ornamental
iron or steel railing. On the roadway will
be laid double track for an electric rail-
way, ten feet on centers; the rails are to
be supplied and the track is to be laid by
the contractor for the bridge. If through
truss design is selected these tracks
will be arranged for an overhead trolley;
if a deck bridge type Is selected, the tracks
will be arranged for the underground or
conduit system. Whatever type is selected
the contractor for the bridge will be re-
qured to do all the work and furnish and
place all the materials necessary for the
complete installation on the bridge of the |
electric railway system.
Col. Allen says that if a through truss
design of bridge is accepted, the upper
chords of the truSses must be straight and
that the right is distinctly reserved to re-
ject all bids or accept that bid which may
be deemed the most advantageous, taking
into consideration all questions of design
and of cost. Although the elevation of the |
roadway at the abutment lines is not speci- |
fled it is desired to keep it as low as posi-
BILE.
IF the lower chords of the trusses of
the accepted design are straight" says |
Col. Allen, 1.-The clearance under the draw
span will be twenty-one and a half feet, !
and under the spans adjoining abutments
seventeen feet; the clearance under the |
spans to be in proportion In
case a curved bottom chord is accepted
the clearance for a distance of forty feet
on each side of the center of the draw and
of the two adjacent spans must be at least |
twenty-one and a half feet. The clearance
at centers Of the spans adjoining the abut-
ments must be at least seventeen feet and
at the centers of intermediate spans this |
clearance must be In proportion. In the |
span extending over the river drive on
Potomac Park this clear head room of at
least seventeen feet must be carried over |
Wo-thirdS of the width of this driveway
Whatever design is accepted, no portion of |
the steel superstructure shall extend below |
a plane ten feet above mean low water
In case through truss design of bridge |
and swing draw span are adopted. the |
draw span will be 200 feet in length be- |
tween centers of rest piers, the pivot pier |
will be forty-seven feet in diameter under |
the coping, the sides vertical and the two |
draw openings will be each 100 feet in clear |
width.
plans may be submitted for a bascule |
draw span instead of for a swing span. |
and in this case the clear opening of the !
draw span will be $50 feet. The bascule |
will be properly counterbalanced and may |
be of the trunnion, rolling lift. roller lift. |
or any other practicable type which has |
been successfully installed and operated in |
other localities. Its width, CARRYING ca |
pacity, time of operation, ETC., must con-
form strictly to similar requirements for |
the swing span.
Rule fer Bidding.
1.-THE prices bid for the superstructure |
will include the construction Of a sheet |
asphalt pavement over the roadway and |
a granolithic pavementrfor the sidewalks |
Bidders will, however, submit PROPOSE
ton, as provided In the proposal, stating |
by what sum the total price for the super |
structure may be diminished in case a tenn |
pcrary wooden plank floor is substituted |
for the asphalt flooring specified The |
mean range of tide is three feet The max |
imum observed freshetfheight at the site |
of the bridge is 1879 feet above low tide |
The river is subject in an ordinary season |
to one or two spring floods following |
heavy rains in the upper valley during |
which times the water may rise to a level |
six or eight feet above mean lou tide