Agriculture Reference
In-Depth Information
Figure 7.15-A. Contours that are spaced farther apart, as shown in Fig-
ure 7.15-B and C, have slopes that are less steep. Compare the horizontal
spacing of the contours of a less steep slope with the contours that are
closer together in the same figure. Slope in site grading is described as
a percentage, so two contours that are a horizontal distance of 100 feet
apart represent a 1% slope, as in: 10´/1000´ = .01 or 1%. Contours with a
one-foot contour interval that are 10 feet apart represent a 10% slope:
10´/100´ = .1 or 10%. The slope for a parking lot can vary from as low as
1% to as steep as 3% or 4%. A tennis court should be graded so that the
maximum slope is 2%, with 1 to 1.5% slopes preferred to facilitate com-
fortable play. An urban plaza might be designed with 1% to 1.5% change
of slope variations, and in some situations can be graded less than 1%
for smooth concrete surfaces. A plaza surface graded to 3% or 4% will
feel “steep” and uncomfortable, when in fact the slope would in other
situations feel like an acceptable, gentle sloping surface. In situations
where the existing terrain is highly varied, in that the elevation differ-
ence from one end of the property to the other has a 100-feet elevation
difference, steeper slopes might be necessary to accommodate a walk or
trail between two buildings or between a building and a parking lot or
outdoor use area. In this case the walk might be graded to 4% and 5% to
a maximum of 8% to accommodate ADA mobility standards, as shown
in Figures 7.16-A and B.
Figures 7.16-a and 7.16-B
Wheelchair access provided on steep hillside slope leading from a lower garden to upper
museum buildings at the Getty Museum, Los Angeles, CA
