vertical tangent (PVT), low point (LP), and high point
(HP) of the curve;
c.
Curve elevations for all stations in b above;
d.
Tangent gradients; and
e.
Vertical curve number for identification.
12.7
Grading guidelines:
Maximum Slope
Minimum Slope
Preferred
Condition
Lawns
25%
4:1a
2%
50:1
2- 10%
Turf athletic area
2%
50:1
0.5%
200:1
1%
Berms and mounds
20%
5:1
5%
20:1
Mowed slopes
25%
4:1a
20%
Planted slopes and Beds
10%
10:1
0.5%
200:1
3-5%b
Road crown
3%
33.3:1
2%
50:1
2.5%
Roads, longitudinal*
20%
5:1
0.5%
200:1
1-10%
Walks, longitudinal
10%
10:1
0.5%
200:1
1-5%
Parking, longitudinal
5%
20:1
0.25% 400:1
2-3%
a.
The maximum slope for mowing machinery is 25%.
b.
Slopes over 6% should have erosion protection.
c.
Accessible routes used by people with disabilities shall conform
to the criteria of Article 2, paragraph 2.4 of this Design Manual.
Payload is drastically reduced on heavy trucks sustaining grades
*
over 3%. Ideal maximum sustained grade for safe operation of
trucks and automobiles is 6%. On roads subject to frequent icing
and winter conditions, the maximum sustained grade is 5%.
13.
LAYOUT DESIGN:
13.1
General: Provide complete dimensioned layouts for vehicular and
pedestrian pavement, structures, and other components of the site
and landscape design. Establish control for the layout by a base
control line with dimensions from this line. Small scope projects
may use property lines for control. Larger projects require
coordinates on a grid system (see VA Program Guide PG-18-4).
13.2
Include on the layout drawings:
A.
Beginning point.
B.
Dimension, angles, coordinates, and curve data for:
1.
Roads, walks, ramps, walls, fences, landscape components
and accessories, curb ramps, lawn mower crossings, corners
of buildings, entrances and other critical elements.
2.
Storm drainage inlets, detention ponds, open drainage
systems, and other surface storm water management
components.
3.
Service areas and docks.
4.
Parking areas, parking striping and other pavement
marking.
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