Storm Event
|
Inches of Rainfall
|
---|---|
2 years
|
3.0 inches
|
5 years
|
4.0 inches
|
10 years
|
4.8 inches
|
25 years
|
5.3 inches
|
50 years
|
6.0 inches
|
100 years
|
6.7 inches
|
|
“n” Factors
| |||
---|---|---|---|---|
Pipe Diameter
|
Helical
|
Annular
| ||
(inches)
|
Capacity
|
Velocity
|
Capacity
|
Velocity
|
up to 18
|
.017
|
.014
|
.026
|
.024
|
21 through 30
|
.021
|
.017
|
.026
|
.021
|
larger than 30
|
.026
|
.019
|
.026
|
.019
|
|
Maximum
|
Minimum
|
---|---|---|
Arterial street
|
State highway standards
|
1%
|
Collector street
|
8%
|
1%
|
Local street
|
10%
|
1%
|
Cul-de-sac
|
10%
|
1%
|
Alley
|
10%
|
1%
|
At all intersections, 60 feet each side
|
2%
|
1%
|
Design Speed
(in miles per hour)
|
“K” Crest Vertical Curves
|
“K” Sag Vertical Curves
|
---|---|---|
20
|
10
|
20
|
25
|
20
|
30
|
30
|
30
|
40
|
35
|
45
|
50
|
40
|
70
|
70
|
45
|
100
|
90
|
50
|
150
|
110
|
55
|
220
|
130
|
Street Classification
|
Right-of-Way Width
|
Streets w/o Curbs (allowed by waiver only)
|
Street Width with Curbs
| |
---|---|---|---|---|
Paved Cartway Width
|
Improved Shoulder Width (each)
| |||
Arterial Streets
|
Subject to PennDOT requirements
| |||
Collector Streets
|
60 feet
|
34 feet
|
8 feet
|
34 feet
|
Local Streets*
|
50 feet
|
26 feet
|
4 feet
|
30 feet
|
Cul-de-sac Streets
|
50 feet (120 feet at turnaround)
|
26 feet (100 feet at turnaround
|
4 feet
|
26 feet
|
Alleys**
|
18 feet
|
12 feet
|
|
N/A
|
*Pavement width shall be increased where on-street parking is
planned or lots average 80 feet or less in width.
| ||||
**Cartway width dependent on oneor two-way traffic.
|
Number of Lanes
|
Cartway Width
|
---|---|
Three lanes
|
36 feet
|
Two lanes
|
24 feet
|
One lane
|
12 feet
|
Acer rubrum cultivars
|
Red Maple
|
Aesculus x cornea
|
Red Horsechestnut
|
Cladrastus lutea
|
American Yellowwood
|
Fraximus pennsylvania cultivars
|
Green Ash
|
Ginkgo biloba (males only)
|
Ginkgo
|
Gleditsia triancanthos inermis cultivars
|
Thornless Honey Locust
|
Liquidambar styraciflua
|
Sweet Gum
|
Nyssa sylvatica
|
Black Tupelo
|
Quercus acutissima
|
Sawtooth Oak
|
Quercus phellos
|
Willow Oak
|
Quercus rubra
|
Red Oak
|
Sophora japonica
|
Japanese Pagoda Tree
|
Tilia cordata
|
Littleleaf Linden
|
Tilia x euchlora
|
Crimean Linden
|
Tilia tomentosa
|
Silver Linden
|
Zelkova serrata cultivar
|
Japanese Zelkova
|
Pyrus calleryana Redspire
|
Redspire Pear
|