Evening public ledger. [volume] (Philadelphia [Pa.]) 1914-1942, 1922-11-04

m Nnere the structure crosses Wiuc
streets. such as G!rard and Allegheny
kHAvenues. columns were placed IN the
Ettcenter of the cross street. but at IcEigh
2Iavenue there are double car tracks
Icurving NORTH from Lck!gh avenue into
avenue.
This and the height OF the structure
at this point made il undesirable to
place columns in the street, and the
eteel arches Of 1l2 feet six inchcs span
were designated to carry the structure.
The arches were placed over the side
walks of Kensington avenue near the
curb line w:th abutment piers OF con-
crete carried down to rock. The tracks
were spread at this point to bring the
loads out adjacent 10 the arch ribs and
TO the columns which support the span
over the Richmond branch of the Read
ing Railway, which adjoins the arch on
the north.
Where the structure crosses the
tracks of the Richmond branch of the
Philadelphia and Reading Railway
north Of I.chigh avenue. and OF the COW
Meeting railway of the Pennsylvania
Railroad ut Pacific street. spans of 1876
feet and 143 feet, respectively, were
SeQuired.
Through -trusses of the Pratt type
were designed for the Richmond branch
! crossing. two trusses for each track.
with suitable transvevs and longitu-
dinal bracing. These trusses have in
clined end posts and curved top chord.
and are provided with pin bearings al
the points of support. The inside
trusses are supported by lattice trusseS
between columns, with large knee
braces attached to each column. The
longitudinal stiffness of the structure is
secured by the braced towers on either
side If the arch. Expansion is taken
u care Of by allowing the columns at he
north end Of the span to bend. The
elevated railway tracks are about forty
three feet above the street Mt this
point.
At the connectln. railway crossing
j two pony trusses OF the Pratt type;
with inclined end posts and parable!
lchords, carry the structure: Bethlehem
.ams twenty four inches deep span the
ace between trusscs to carry the track
,Or, Knee braces support the top
E ord at each floor beam and the eNdS
the span rest on pin bearings with Il
sler bearing at the south end to pro-
.,e for expansion. The structure at
Ias point is about forty-six feet from
70 street TO the rail, and In order to
slsh adequate support and stitthess;
le span.
Tie engineers were governed in their
,reliminary work by the following
fundamental principles. First. that
"a structure must be of the most
economic type; second, that it should
bpresent the latest developments and
nuroyements in the ART of elevated
Iyav construction. and third. that
tructurc be of n type that VIII be
ole and require the lowest eSpshu!-
for maintenance.
.eful investigations wer" made to
Spuine the most economic sections
;pnns before proceeding with the
Of the structure. The design
d is steel structure with
rs on the sidewalk. supporting
,erse cirder. which, in turn, car
the longitudinal tiusses: these
as. in turn. support beams which
Ey the concrete deck.
<ae column piers are OF the usua!
rectangular base ot Sufclcnt
m load the soil to nbout three and
half tons per square foot, with
midal top. The top cf the p!er
. designed for II bearing prcssur"
jer the column base of 900 pounds
sounre inch. and the minimum dis
nce from the sole plate 10 th" edge
the concrete was feed at six inches.
UNDERGROUND structures were fire.
sntIy encountered on the pier sites,
a In many cases specially designed
r. were required IN order to meet
Of the conditions. south OF n!rnru
,nue and in the vicinity OF Willow
.et soil conditions were not suit,
~ for carrying the piers. and AZ
"a poiuts concrete piles w"rr driven
the gravel strata underlying the
4. and fill.
Two Types of Structure
/. columns are generally formed
isthlehem II and channel sections
mates added where loads 10 be-
ed required larger sections;
.lu,n bases in all cases are formed
~ mates attached to the column
Z BY gusset plates and stnfenrd
angles. Four 1"s.inch diameter
~ were built in each pier to an
~ the columns. Base plates were
from one half to one inch above
q ton of the finished pier, and after
sfructure was levpled and aligned,
space was tampcd full of still
MT mortar; the entire base was
incl0sed in concrete. wn!ch "i
70 formed the sidewalk SURFACE,
tie edge next TO the rartway was
rSnrced with Il steel bound edge
formed the curb. 49,
Mas considered desirable to fl
.ciumns with concrete, both fOI
I've OF appearances and to pre-
4 71he accumulation OF dirt. and tc
~ some benefit from this fil!!nt
additional bearing area. Ih'
irSss were laid on the ground ant
3lled one side at a time will
20 with a grunolithir face. A
VA the concrete had its Initial Sc
.S1rface was rubbed with u hr!cl
Vvashed to remove the film o.
~ from the surface. 1t was neccs'
to have considerable number I"
columns on the street in advance
esoctiOn to permit the concrete t.
Hafd before handling.
H ei,lewalks of Frankford avenue
Snrrow and the people Of Frank
Skjscted to columns being place.
oilswalks. TO meet their OBJ
q special type Of column wa,
VITA 4 single shaft Located