Evening star. [volume] (Washington, D.C.) 1854-1972, 1901-04-18
Plans Submitted by Company's En-
gineer to Colonel Allen.
FEATURES OF PROPOSED STRUCTURE
Height Above Low Mean Water
Mark 211a Feet.
REUSLT OF THE BORINGS

The plans for a new railway bridge to ac-
commodate the tracks of the Baltimore and
Potomac Railroad Company now on the
Long bridge across the Potomac have been
submitted to the Secretary of War by the
engineer of the railroad company and re-
ferred to Colonel Allen, president OF the
board of army officers appointed to make
plans for highway bridge which is to be
at least 500 feet above the present Long
bridge. In number of respects these
bridges will bear close relation to each
other. One being in proximity to the other
it will be desirable to have them of equal
height and the draw of each of the same
style. BY many it is thought the tw9
bridges should be in accord architecturally,
but if this should be made a requirement
by the board it will doubtless be necessary
to insist that the railroad bridge be de-
signed on very different plan from that
which is shown by the drawings submitted
by the railroad company.
The Plan Proposed.
The plan proposed is for what is known
as a Pratt truss bridge of steel, 2112 feet
above low mean water, the present Long
bridge being only 1912 feet above low mean
water The flood of 1889 carried the water
in the Potomac to a height of twelve feet
and seven inches above low mean water,
and above the wood of the bridge floor, so
that loaded coal cars had to be placed on
the bridge to save it from being washed
away. The draw of the proposed bridge is
of the pivot or swing type, which will leave
a channel of 100 feet clear on each side of
the center pier that supports the swing
bridge. Including this center pier the
bridge across the Georgetown channel will
\ 81, ,,,rI, fl,n aIsnr1r al
itself will be in the two 100 feet openings
of the draw.
Beginning on the District end of the bridge
there will be two spans 40 feet three
inches long from center to center of the
piers, two 216 feet three inches, two 140
feet three inches (these form the openings
in the draw of 100 feet in the clear; four
spans 216 feet three inches, two spans 2o3
feet six inches and one span of 1I0 feet
three inches, which reaches to the Vir-
ginia side.
The pier supporting the draw and the
piers on each side of it are proposed to be
built on pneumatic caissons, the other
piers to be on piles and grillage.
Result 0f the Borings.
The borings made below the site of the
draw show rock at a depth of over 100
feet below mean low water level. Four
other borings along the route Of the bridge
were made from the Virginia shore to the
enlbankment on the reclaimed flats, none
Of which reached the rocks. The boring near
the Virginia end of the bridge was carried to
depth of Id feet six inches, the lowest
strata reached being sand and clay. Be-
| tween this boring and the draw two other
borings were made, one to depth of Ill
feet and the other to depth of ninety-siX
feet five inches. Between the draw and the
flats there was one boring thirty-eight feet
three inches deep. The distance between
the piers of the present Long bridge is
about 115 feet.
The law authorizing the construction of
this new railway bridge provided that the
plans should be approved by the Secretary
of War.