Classification
|
Minimum Distance
Between Intersections
(feet)
| |
---|---|---|
Arterials county collectors
|
350
| |
Township collectors, county-locals
|
250
| |
Loop streets, culs-de-sac
|
200
| |
Whenever two roads of different functional classification
intersect, the minimum separation standards of the more important
road shall be followed.
|
Classification
|
Radius
(feet)
| |
---|---|---|
Arterials county collectors
|
40
| |
Township collectors, county-locals
|
30
| |
Loop streets, culs-de-sac
|
20
|
Classification
|
Distance
(feet)
| |
---|---|---|
Arterials
|
400
| |
County major collectors
|
300
| |
County minor collectors
|
250
| |
Township collectors, county-locals
|
200
| |
Loop streets
|
150
| |
Culs-de-sac
|
110
| |
These points are to be connected to a point
90 feet from the intersection of the street center lines. Plates 7
through 10[3] illustrate the required sight-triangle easements. The
sight easement shall describe two overlapping triangles whenever the
intersecting roads are of Township collector or above functional classification.
The easement for intersections involving cul-de-sac or loop streets
shall only include the sight triangle needed for the motorist entering
the intersecting street.
|
Type of Street
|
Lanes No.
|
Width
(feet)
|
Shoulder Width
(feet)
|
Type
|
R.O.W.
(feet)
| |
---|---|---|---|---|---|---|
County major collector
|
2
|
12
|
6
|
1
|
86
| |
County minor collector
|
2
|
12
|
6
|
2
|
66
| |
County local
|
2
|
11
|
6
|
2
|
50
| |
Township collector
|
2
|
11
|
6
|
1
|
50
| |
Loop
|
2
|
11
|
5
|
1
|
50
| |
Cul-de-sac
|
2
|
11
|
3
|
1
|
50
|
Q =
|
Volume of run off in cubic feet per second
| |
A =
|
The contributory drainage area, in acres, both
within and outside the boundary of the subdivision.
| |
I =
|
Coefficient of runoff applicable to the drainage
area. It shall consider the soil character, slope of area and degree
of ultimate development as determined by current zoning. In general,
the values of the run off coefficient will fall within the following
range:
|
Classification
|
Coefficient
| |
---|---|---|
Park lands, golf courses, etc
|
0.15 to 0.30
| |
Densities below DU/acre
|
0.30 to 0.50
| |
Densities of 2 DU/acre and above
|
0.50 to 0.70
| |
Commercial and industrial
|
0.70 to 0.90
|
For composite areas of various classifications,
the coefficient for the predominate area shall be used for all calculations.
|
R =
|
Rainfall intensity. A minimum intensity of 2.75
shall be used.
|
V = 1 486R2/3S1/2
n
| ||
R =
|
Hydraulic radius of conduit, or area of stream
divided by wetter perimeter.
| |
S =
|
Slope of hydraulic grade line, or for open channels
or ditches, the slope of the water surface.
| |
n =
|
the coefficient of friction.
| |
Acceptable values of "n" are:
| ||
.015 for circular cross section, nonporous concrete
pipe.
| ||
.015 for pipes 18 inches or smaller in diameter
and concrete lined ditches.
| ||
.025 for clear unlined ditches.
| ||
.03 to .15 for fair to poor natural streams
and watercourses.
| ||
Other cross sections of pipe materials shall
have commensurate friction factors as may be approved by the Township
Engineer.
|
Permissible Design Velocities Open Channel
Ditches
| ||
---|---|---|
Material
|
Velocity
(feet per second)
| |
Fine sand to loam
|
2.5 to 3.5
| |
Clay to hardpan
|
3.75 to 6.0
| |
Concrete lined
|
15
| |
Pipe
|
*
| |
*Minimum design velocity at "flowing full" condition
shall be three feet per second. Pipes shall be considered "flowing
full" at maximum capacity.
|