The Evening standard. [volume] (Ogden City, Utah) 1910-1913, 1910-09-17
SOUTHERN PACIFIC
BIG BRIDGE OPEN

The Southern Pacific railroad Mon
DAY lnaugurated a freight service oveI
the Dumbarton bridge, which crosses
inc southern end of San Francisco
bay The bridge Is steel structure
win double tracks. 1900 feet In
length Together with the cutoff line
which runs from Newark In Alameda
county TO Redwood City. in San Mateo
county. 1t cost $i.O0u0O0.
The cutoff Is primarily for freight
passage and viii carry all northwest
ern sffd eastern shipments into and
out Cf San Francisco. Hitherto freight
mas peen ferTied across the bay.
ne work OF constructing the foun-
datlons for this new bay cut off was
IN charge OF c. h. Broughton. who
TOOK command at the death OF w. e.
Marsh.
Mr.. Broughton is we'll known in
ogden. He was with Mr Marsh when
the latter had charge OF the construc-
ton OF the Lucin cut-on across the
Great Salt Lake. and his vast expert
ence and general knowledge were of
invaluable service in the erection of
both projects.
Mr.. Broughton spent considerable
tlme In this city in 1902 and 1903, and
was married to Miss Ella Conroy, a
sister to Or. Z. NJ. Conroy of this city,
while engaged in the building OF the
DOcin bridge.
Inc erection of the superStructurc
OF the Dumbarton Point bridge of the
southern Pacific company across the
lower end OF San Francisco bay was
intended 10 meet the deep water and
swift current conditions presented at
the site. The bridge includes a $40
loot drawSpan. with three lS0-foot
liked spans at both ends, and is de-
signed as double track structure. ac-
cordlng TO the common standard speci-
hcationS of the Hartman lines The
channel is. approximately. 500 feet
wide at the bridge, and on both sides
OF 1t are stretches OF low fiat salt
marshes. At both ends OF the struc-
ture are long timber-pile trestle ap.
proaches which give the latter a total
length of 1892 feet.
The water in the middle OF the
channel is about SO feet deep at low
tide, the extreme variation being II 7
feet The bay widens beyond the
crossing. TO that considerable water
ebb and flow OF the tide consequently
are very swift through the narrow
channel at the bridge These condi.
tons and the character OF the bottom
required quite special design for the
Superstructure.
The ends OF the spans arc carried
by pairs OF concrete cylinders, built
in steel shells.
The depth OF the water at the site
and the swift current of the tide led
TO the decision TO erect the spans on
temporary falsewoTk driven in shallow
water adjacent TO the site, and then
to tow them To place in scows.
Tho ialsework had under each panel
point OF both steel spans. except for
two 4I-foot gaps in each case. two
pilc-bents driven and braced to make
pier
The hull of An old car ferry, 2iS feet
long, was cut in two at the middle and
the ends OulBheadcd TO make two huns
that were used In floating the spans TO
place. BulkheadS in each of these
hullS divided the latter into fvc com
partments, which were provided with
sea valves TO permit water TO be
was ready To be moved, scowS were
run under it at low tide. and as the
tide rose, the span was lifted from
the temporary falsework so that It
could be towed out on the hulls to its
final position. The lowering of the
spans TO the bridge seats was accom-
plished quite accurately and with com
paratiyc case by filling the compart-
ments of the hulls with water admit.
ted through the sea valves. When the
hullS carrying the span were in the
proper position they were anchored
by means of ropes TO the piers, and
the ends Of the span. were lashcd TO
the latter with ropes rove through
blocks so they could be shifted slight.
ly as the lowering proceeded. As the
placing Of the spans occupied such a
comparatively short time. tho fall of
the tide could not he utilized. so de-
pendencc on the filing OF the scows
with water was practically the sole
means of bringing the spans TO rest.
Tho bridge was designed and built
under the direction of Mr.. William
Hood chief engineer of the Southern
Pacific company. The late w. E
Marsh was in charge Of the construc.
tion of the foundations and the cree.
ton of the superstructure until tho
time of his death. when he was sue.
ceeded by Mr.. c. r Braughton.