Required For All Roads Except Local Class
II
|
Required For Local Class II
| |
---|---|---|
Paved streets
|
Yes
|
Yes
|
Curbs and gutters
|
Yes
|
Yes
|
Sidewalks
|
Yes
|
No
|
Water mains and fire hydrants
|
If available
|
No
|
Sanitary waste disposal
|
Yes
|
Yes
|
Storm drainage
|
Yes
|
Yes
|
Street signs
|
Yes
|
Yes
|
Streetlighting
|
Yes
|
No
|
Street and shade trees
|
Yes
|
Yes
|
Street Class Major Collector
(feet)
|
Minor Collector
(feet)
|
Class I & II Local
(feet)
| |
---|---|---|---|
Minimum center-line radius
|
600
|
500
|
300
|
Minimum tangent between reverse curves
|
200
|
160
|
120
|
Intersection radius (curb returns)
|
40
|
30
|
25
|
Minimum intersection radius shall be determined
by the highest street class in the intersection, and the right-of-way
line shall be concentric thereto.
|
L=KA
|
---|
The minimum "K" values shall be as follows:
|
Street Class
|
Crest Curve
|
Sag Curve
|
---|---|---|
Major collector
|
145
|
100
|
Minor collector
|
65
|
60
|
Local
|
28
|
35
|
Intersection (stop conditions) (Rounded by PC/PT
of curb returns)
|
3
|
3
|
[Based on height of drivers eye of 3.75 feet
above road surface. Height of object five-tenths (0.5) feet above
road surface.]
|
Street Class
|
Sight Distance
(feet)
|
---|---|
Major collector
|
350
|
Minor collector
|
275
|
Local
|
200
|
Residential
|
Width Minimum
|
Maximum
(Feet)
|
---|---|---|
Single driveway
|
8
|
20
|
Double driveway
|
16
|
20
|
Other uses
|
25
|
40
|
Street Class
|
Minimum Average Maintained Footcandles
|
Uniformity
(average to minimum)
|
---|---|---|
Major collector
|
0.5
|
6:1
|
Minor collector
|
0.3
|
___
|
Local
|
0.2
|
___
|
Q = CIA
| |
Where:
| |
"Q" is the required capacity, in
cubic feet per second, for the collection system at the point of design.
| |
"A" is the tributary drainage area,
in acres, and shall include areas tributary from outside sources as
well as from within the site itself.
| |
"C" is the coefficient of runoff
applicable to the drainage area and shall be based on consideration
of soil conditions, average slope of the drainage area and degree
of ultimate development of the area, but in no case shall be less
than the following coefficients:
|
Usage
|
Density
(units per acre)
|
Topography
| |||
---|---|---|---|---|---|
Flat
(0-10%)
|
Rolling
(10-20%)
|
Hilly
(Over 20%)
| |||
Residential
| |||||
High density
|
4-6
|
0.50(0.40)
|
0.55(0.45)
|
0.60(0.55)
| |
Medium density
|
1-4
|
0.45(0.35)
|
0.50(0.40)
|
0.55(0.50)
| |
Low density
|
Fewer than 1
|
0.40(0.30)
|
0.45(0.35)
|
0.50(0.45)
| |
Impervious surfaces
|
0.90
|
0.90
|
0.90
| ||
Undeveloped woodland
|
0.30(0.20)
|
0.35(0.25)
|
0.50(0.45)
| ||
Pasture and grassed areas
|
0.30(0.20)
|
0.36(0.20)
|
0.42(0.37)
| ||
Cultivated fields
|
0.50(0.50)
|
0.60(0.50)
|
0.72(0.62)
|
The above runoff coefficients assume that clay
soils (sand gravel soils coefficients indicated in parenthesis) are
present and that paved areas (parking) have been provided, and any
deviation from these factors would result in an adjustment in "C"
values. Determination of nonlisted uses shall be a subject of special
study and approved by the Township Engineer.
|
"I" is the rainfall intensity, in inches per
hour, and shall be determined from the graph entitled "Rainfall Intensity
Duration for Essex and Union Counties," copies of which are on file
with the Township Clerk and is made a part hereof. The minimum time
of concentration shall be 10 minutes, which shall be used as the initial
Tc for all roadway drainage systems.
|
V = 1.486 R 2/3 S 1/2
|
"R" is the hydraulic radius of the conduit flowing
full.
|
"n" is Manning's roughness coefficient, which
shall be as follows:
|
Concrete pipe
|
0.012
| |
Corrugated metal, 2 2/3 x 1/2 inches corrugations
| ||
Plain or fully coated
|
0.024
| |
Paved invert
|
0.020
| |
Fully paved
|
0.012
| |
3 x 1 inches corrugation
|
0.027
| |
6 x 2 inches corrugation (field bolted)
|
0.032
|
"n" for other materials shall be as recommended
by the Township Engineer.
|
"S" is the slope of the energy gradient, in
feet per foot, and shall generally be considered as being the same
as the slope of the invert of the pipe (So); however, such slopes
shall be checked against the available hydraulic gradient whenever
the system flows full or where the system discharges into a body of
water.
|
Desirable Minimum Gradients for Concrete
Pipe
| |
---|---|
Diameter
(inches)
|
Slope N=0.012
|
15 (minimum permissible)
|
.008
|
18
|
.006
|
24
|
.005
|
30
|
.004
|
36
|
.003
|
42
|
.002
|
48
|
.0016
|
54
|
.0014
|
60
|
.0012
|
66
|
.0011
|
Unlined
| |
---|---|
Earth, uniform section
|
0.018-0.027
|
Earth, nonuniform section
|
0.025-0.040
|
Earth, not maintained
|
0.080-0.012
|
Lined
| ||
---|---|---|
Concrete
| ||
Finished
|
0.015
| |
Rough
|
0.25
| |
Riprap
|
0.35
|
Materials
|
Velocity
(feet per second)
|
---|---|
Fine sand to fine loam
|
2.5 to 3.5
|
Stiff clay to hardpan
|
3.75 to 6.00
|
Concrete-lined ditch
|
15
|
Velocities shall be controlled by use of check
dams or baffles where necessary.
|
Facility
|
Maximum Side Slope
|
---|---|
Channel
|
2:1
|
Ditch
|
4:1
|
Swale
|
6:1
|