98 
PARK AND CEMETERY. 
PREVENTING EROSION ON ROADWAY GRADES 
Erosion has long been a troublesome fac- 
tor in the maintenance of roadways built 
of macadam, gravel and slag. This has 
The gutters completed, and the diverters 
in position, the spaces are filled with the 
material selected for the roadway and the 
is a proportion of 1-2-4. The fresh con- 
crete is covered with earth as soon as the 
forms are removed and kept moistened for 
FIG. 1. FRAMEWORK OF FIG. 2. THE COMPLETED SKEL- FIG. 3. THE COMPLETED ROADWAY 
ROADWAY DURING COM- ETON; STONE BEING DUMPED AFTER ONE YEAR'S SERVICE. 
PLETION. IN. 
been met, in part, by the use of gutters 
of various design and material and has 
been effective according to the steepness 
of the grade, the material used in road 
building and the length of the incline. Pav- 
ing and concrete are sure preventatives 
of erosion, but carry first an almost pro- 
hibitive expense in building and, due to 
their smooth surfaces, are unsuited to the 
steeper grades during certain seasons of 
the year. 
The following is the method employed 
at Grand Lawn in road building on grades. 
The first cost is exceptionally low, the 
maintenance small, the appearance of the 
roadway is unaltered and is effective in 
preventing , erosion. 
Fig. 1 shows the framework of the road- 
way during completion. It is merely an 
application of the old-fashioned "Thank- 
you-mam” with the bump left out. The 
concrete gutters are built first, and after 
any method approved by the builder. The 
“diverters,” also of concrete, are built to 
fit them. The distance between the insides 
of the gutters in the illustration is 13 
feet, the road being 18 feet wide and the 
gutters 30 inches. The crown of the road- 
way is 6 inches. As the road and grass 
sides of the gutter are at the same level, 
the entire crown of the road is thus given 
between the inside edges of the gutters, 
the crown thus given being a little less than 
one inch to the foot. The grade on this 
roadway is 12 per cent. 
The diverters have a slope of 30 degrees 
with the transverse axis of the road and 
their upper surface of the forms in which 
they are built must be ascribed to fit the 
curve of the road in this position. These 
curves can be readily computed by well- 
known methods. The diverters should be 
nine inches wide and not less than one 
foot in depth. The upper surface is not 
level, but conforms exactly to the incline 
of the grade. The diverters are spaced IS 
feet apart. / 
road roller may be used to compact it. 
The spaces must be well filled with ma- 
terial or the shock of the roller striking 
the unprotected concrete will damage the 
work. The only weak spot in the method 
that the writer is aware of lies in the fact 
that the roadway can be rolled in only 
one course. 
Fig. 2 shows the completed skeleton and 
the crushed stone being dumped in place. 
The concrete mix'ture used in this work 
about two weeks. This thoroughly cures 
the concrete and enables it to withstand 
the hard wear to which it is subjected. 
Fig. 3 shows the completed roadway after 
one year’s service and with no maintenance 
whatever since its completion. This road- 
way on a 12 per cent grade withstood a 
rain of 1.24 inches which fell in a little 
less than one hour. E. B. Wilhelm. 
Detroit, Mich. 
BUILDING SCENIC PARKWAYS 
The construction of Hillside and Ter- 
williger parkways, two of the fine scenic 
drives in the park system of Portland, Ore., 
involved some unusual problems in park 
roadway building that make a study of the 
details of these improvements worthy of 
especial note. 
SECTION OF TERWILLIGER PARK- 
WAi, SHOWING CCRYATURE AND 
COMPLETED GRADING. 
These two parkways are normally 200 
feet in width, with a maximum grade of S 
per cent, mostly 2 and 2 y 2 per cent ; the 
shortest outside radius, 117 feet; inside 
radius, 72 feet. The typical section from 
property line to property line is as fol- 
lows : Beginning at the upper side, prop- 
erty line to gutter, 17^4 feet; gutters, 2, 
each 3 feet; gutters and roadway, 36 feet; 
from edge of lower gutter to edge of walk, 
9 feet. The paving is to be hard surface, 
“Tarvia.” 
The lighting is to be underground elec- 
tric, with lights spaced 150 feet apart, and 
single solid concrete reinforced lamp posts, 
surmounted by 400 watt lamps enclosed in 
20-inch globes. 
The plantations are all native. That is, 
where there is no existing vegetation it has 
been supplemented on cuts and fills by ma- 
terial indigenous to the locality. 
The drive is to commence in the heart 
of the city, and when this present section 
is completed it will reach the river, a dis- 
tance of approximately seven miles. The 
highest point reached is 500 feet, city 
datum. The views give a fine panorama 
of the city and Willamette Valley and the 
Cascade range, with the prominent snow- 
clad mountains, namely, Three Sisters, Jef-' 
