Evening star., 1901-12-17

IS feeu6u ABOVE. tne mHxfmum 1rcSnee line
to prevent injury to the bridge. The board
says: THE clear head room of 2l feet s
inches above low tide (as proposed by the
Baltimore and Potomac Railroad Company
for the new Long bridge) Is regarded as
sufficient for this purpose. The general
Grade of Potomac Park under the present
project is three feet above the freshet
line of 1877, and this grade at the proposed
site of the high bridge would be about 13
feet above mean low tide. On the Virginia
Side of the river the general level OF Alex
ander's Island. near the Long bridge, may
be stated at from to feet above mean
low tide. With a clear head room of p
feet inches the grade Of the roadway of
the bridge would need to be at least from
p to 80 feet above low tide, and the ap-
proaches on each side would have to rise
accordingly in order to reach the bridge
grade, and should be formed by embank-
ments. From consideration of aesthetic
design it might be desirable to use an
arched girder or arched truss. The
board carefully considered this subject, and
their reasons for not recommending a
bridge of this type are given In some de-
tail"
Design Within the Appropriation.
"Rega riding the amount of the appropria-
tion made by the act of February u, 1901,
viz, $56S 600, and taking into consideration
also. the great length of the bridge and ap-
proaches. effort has been made to design a
suitable work, the cost OF which-contin-
gencies of con ,truction and engineering in
cluded-would come within the sum avail
able and at the same time, admit of car,
wagon and pedestrian traffic; one that
would afford good egress for the passage of
floods. and generally come within the re-
quirementS of the act. The effort has been
made to get the most for the money avail
able The best that offers, in pursuance of
the foregoing, for the sum named, is COM
prised in a scant construction of uninvit
ing appearance with roadway to be 81
feet and sidewalk five feet in width the
roadway to have but one car track. for
which an allowance of 10 feet in width is
made, the track being on the east side of
the way. leaving for carriageway and
wheel guard, II feet"
Objections to the Plan.
The board says that this design is not be-
leved to be in accordance with what Con-
gress would desire.
at is necessarily incomplete as to side
walks" says the board, both ON the bridge
and on the approaches, while the temporary
character of the flooring of roadway and
sidewalk on the bridge and of the entire
pile and trestle portion of the Washington
approach are undesirable features of the
design. Further, it considers but one track,
whereas the act of February IL, 1901, evil
IDENTIFY requires provision for al least two in
addition to roadways for highway traffic.
While it is probable that the bridge and
approaches indicated can be constructed by
contract within the appropriation, the board
does not believe them suitable or adequate
for the purpose, and therefore recommends
that this design be not adopted. In lieu of
a highway bridge and approaches. as just
described. and which. though on as good
basis as, in the opinion of the board would
be likely to be obtained for the amount of
money appropriated by the act of February
II. 1901, there is here presented for consid-
Grafton another design (No. .. the principal
points of which are as follows, II being
borne in mind that, as required by the said
act, the bridge is to be of iron or steel, rest
ing on masonry piers and with suitable ap-
proaches:
The Proposed Plan.
This proposed plan is to consist principal
ly of eleven fixed spans of PIG feet each, or
211 feet inches between centers Of end
pins, and one revolving ChorizontaD draw
span of go feet to afford clear opening
of 100 feet on each side of the pivot pier;
the superstructure to be of steel and to
rest upon stone piers The structure is
provided with double tracks for the passage
of electric cars, the total width of roadway
for cars and vehicles being forty feet be-
tween wheel guards, and the sidewalks,
one each side of the bridge, eight feet
wide in the clear; the total width of super
structure from out to out of sidewalk rail-
ing being about siXtytwo feet The side
walks are granolithic pavement and the
roadway of sheet asphalt, supported on
buckle plates. The draw is operated by
operated by electric power through trolley,
overhead on the bridge proper and on the
approaches on the Virginia side and sunken
on the park approaches on the Washington
form of through truss is one with q curve
top chord. The Pratt truss, with a curved
top chord. is probably the most economical
truss which can be used for spans of the
length here proposed, and, furnishing for
tunatey a somewhat pleasing appearance,
has been adopted in this design. No 2
The approaches across Potomac Park will
be of earth embankment, with moderate
slopes, excepting that a portion of the
tidal reservoir in Potomac Park will be
crossed by a steel plate girder, which may
receive more or less ornamentation. A
clear space of 100 feet is to be left between
the southeriy end of the embankment and
the sea wall of Potomac Park for walks and
driveways. This 1OO?foot space at the sea
wall is regarded as ample.
In Relation to Potomac Park.
1.-THE earth slopes of the approaches along
the crossing of Potomac Park can be event
ually sodded. spaces being left for trees,
flower beds, shrubs, &C., similar to those in
some of the parks of Washington and other
cities, affording pleasing and economical
ornamentation The crossing of the park
by the highway bridge infrnges upon the
park arsa and drives, but it seems to be
unavoidable and the adjustment of the re-
lation of bridge approach to park drives
and areas can only be harmonized when de-
tails and final plans for both are drawn
Railings and posts for lights are to be pro-
vided for the bridge and both approaches.
The piers and abutments on the bridge will
rest on foundations of deeply driven piles,
the borings and pile tests giving confidence
that such foundations will suffice and be
economical. The total cost Of design No.
2 Is 1896, Goo of which the principal item,
1927 900, is for eleven fxed spans. The
above includes asphalt roadway, granolithtc
sidewalks curbs, ratings, lamps. &c.
The Boards Recommendation.
1.-The board is OF the opinion that In order
to meet the requirements of the locality and
traffic, as well as to comply with the terms
of section IL Of the act Of February II.
1901. the bridge to be built under authority
of that act must be substantially Of the
character and dimensions indicated in de-
sign No. 2. It is therefore recommended
that this design No. 2 be adopted. and that
the bridge be built in general accordance
Herewith, 1t being distinctly understood
that this design Is but general in character
- <I.an