The Seattle post-intelligencer. [volume] (Seattle, Wash. Terr. [Wash.]) 1888-1914, 1893-04-10
BRIDGING THE GORGE
Great Engineering Work Over
the Columbia River.
GREAT NORTHERN CROSSING.
Di0esltiss lEss aaA How Ihsy We're
Ovsrssns Erie EnginesRs' Exhibit
&C the fsir-New Motive Power.

WxsArcHEE. April a-Ths longest span
Of the great cantilever bridge Of the Great
Northern railroad over the Columbia river
at Rock Island b at last completed and
the whols bridge viii b ready for the run.
ming Of trains about May L The work Is
the successful solution Of great problem
and il one Of the RreatestfeatS Of engineer.
ing skill in the history Of railroad build
ing.
The Columbia river in this part a ito
course IL between 800 and 1000 yards wide
and from u to 200 feet in depth at low
water. Its channel u worn deep below the
general surface Of the valley. and though
the annual rise In June IL from thirty-five
70 fifty feet, it never overf1ows. How and
p0rtant problem for the Great Northern
Railway Company. Either . drawbridge
must Be constructed, which could be most
easily done where she river is shallow. and
consequently wide. making long bridge
supported on piers, or span must b
thrown across above high water high
enough not to interfere with navigation.
After many surveys and measurements
the company decided on tho latter plan,
and . site was selected mile and half
above the station of Rock Island and nine
miles below Wenatchee.
At that point basaltic butte rises 500
feet above the valley. through the eastern
spur Of which the river channel has been
cut. The butte drops down to the river in
shelf-like terraces, and on one Of these
shelves the road approaches the west end
Of the bridge. On the east bank stands .
huge basalt rock. rising 200 feet above the
water, and through 1t roadway has been
cut for the eastern approach to the bridge.
Two hundred and fifty feet from the east
bank IL an island or rock, on which the
only pier in the river Is built. and between
the rock and west bank flows the main
stream, 4l6 feet wide and l43 feet in depth.
The whole bridge is 9l6X feet long. not
counting minor approaches. and 10 10 feet
above low water and 20 feet above extreme
high water. The first span reaches from
the bluff on the west side $50 feet over q
shelf to the water line. The second or
main span reaches 4i6k feet over the main
channel to the island. 1t weighs $50 tons,
and in the center il - feet from top to
bottom of tho. structure. The third span
u from the island to the east bank. The
whole is framework of steel and wrought
iron. built by the Edgemore Bridge Works,
of Wilmington, DEL, and is erected under
the superintendent Of ]. A. Sheedy,
whose competence is shown by the fact
that mp to this time not an accident or
mishap has occurred on the work.
When completed each span will be sep
arate and independent Of the others, but
In the construction an ingenious and
original plan was adopted. Its great
height and the depth of the water below
made It impossible to put up any false
work to support the main span: each of
the side spans has been erected upon false
work. but In an inverted position in such
. way - to act a. the long arm of lever.
and the outer ends loaded each with 400
tons Of steel rails to balance half Of the
main span ~ It II projected over the abyss
below. The work from the two sides was
Joined BY steel ties during the last few
days % that the workmen and others who
had the nerve crossed on foot, but the two
ends have now been Joined. In order to
make certain Of having the two spans como
exactly together, the western arm was pro-
jected at slight rising angle, and at ito
junction with the temporary span sup
porting Il four steel wedges, each ten feet
in length and fitted with screws for
moving, are 30 arranged as to bring the
immense mass to its proper place. Now
that the main span il finished and no
longer requires the support of tho end
spans. these two will be taken down and
ofecfed IN THAR pvnoop pos;t;ov