HomeMy WebLinkAboutSUB202000059 Correspondence 2020-03-30SHIMP ENGINEERING, P.C.
Design Focused Engineering
ECO VILLAGE CHARLOTTESVI LLE
PAVEMENT DESIGN SPREADSHEETS
912 E. High St. Charlottesville, VA 22902 1434.227.5140 1 shimp-engineering.com
Table 1
Classification, Load Support Characteristic, and Resiliency Factor of
Common Soils in Virginia
Mica Content
Load Support
Resiliency
Soil Classification
Characteristic
Factor
a) A-1 & A-3 Soils
b) A-4, A-5 and A-7 soils having a sand content greater than 60%
Excellent
3.0
A-2, A-4, A-5, A-6 and A-7 soils having a sand content between 40%
and 60%.
a
Good
2.5
A-2, A-4, A-5, A-6 and A-7 soils having a sand content less than 40%
Average
2.0
Without Mica
a) A-7-5 soil.
b) soil with low or trace mica content and having an average group
index (GI) below 5
Poor
1.5
c) A-2, A-5, A-6, and A-7-6 soils with low or trace mica content
Soils not within the category of Medium Low Resiliency Soils and also
Very Poor
1.0
With Mica
contain mica.
APPENDIX I
Predicted Resiliency Factors, CBR and Soil Support Values
Values may be used for preliminary pavement design only. Final designs must be based on soil tests.
NOTE
Appendix I shall not be used and SSV shall not exceed a value of 2 when the moisture content of the soil exceeds
the plastic limit, approaching the liquid limit (e.g. high water table or other reasons).
Regional Chart of Soil Resiliency Factors
Table of Values by County
County Code
County
RF
CBR
SSV
00
Arlington W. of Rte. 95
E. of Rte. 95
1.0
3.0
7
10
7
30
01
Accomack
3.0
7
21
02
Albemarle E. of Rte. 29
W. of Rte. 29
1.0
1.0
4
5
4
5
03
Alleghany
2.0
5
10
04
Amelia
1.5
6
9
05
Amherst
1.5
5
7.5
06
Appomattox
1.5
5
7.5
07
Augusta
2.0
6
12
08
Bath
2.0
5
10
09
Bedford
1.5
5
7.5
10
Bland
2.0
6
12
11
Botetourt. From the western base of the Blue Ridge
Mountains to the east
1.5
4
6
Appendix II
Nomograph for Determining Required Pavement Thickness Index
(Note: An enlarged vasion of this nomograph isprovided on the last page of this reference.)
Final pavement design must be based on the results of appropriate soil tests.
Preliminary designs may be based on values established in Appendix I.
(Nomograph omitted to save space.)
To determine DR, project a line from the value for SSV through the value for the Design AADT.
The nomograph depicted correlates the soil support value of the subgrade (SSV =Design CBR x RF),
the traffic volume (Design AADT), and the minimum required pavement design thickness index (DR)
for subdivision streets and secondary road pavement, based on AASHO design equations. The equation
on which the nomograph is based is: DR = 3.48Ln (AADT)-1.48Ln (SSV) - 7.23, where Ln is the
natural logarithm. This nomograph assumes the following:
1. Use of Design AADT for two way traffic, equally distributed, thereby deriving the
thickness index (DR) required for any portion of the pavement to support one-half of the
design AADT.
2. For DR greater than 20, staged consttuction providing an initial stage DR value of 20 may
be permitted or the road can be designed using primary pavement methodology.
The District Materials Engineer may consider reducing the minimnm DR value of 6.4 for
secondary system facilities having a Design AADT <50.
Computation from equation
Road A
AADT
281
CBR
6
RF
1
SSV
4
DR
10.3
HCV
3%
APPENDIX III
Paving Materials & Allowable Values
Max. No. of
Thickness
Lift Thickness
Lifts in a
Equivalency
Value
Design
Location
Material
Min. Max.
Material
& Notation
Notation
inches inches
Asphalt Concrete (SM-9.OA or D)'
1
1.5
Asphalt Concrete (SM-9.5A or D)'
1.52
A.C.
1.67 *
1
13
Asphalt Concrete (SM-12.5A or D)l
2
Surface al
1.25
Prime & Double Seal or Class "C" or D"
a
D.S.
0.84
-
-
1
Blotted Seal Coat Surface Treatments
Intermediate
i
Asphalt Concrete (IM-19.OA or D)
A.C.
1.67
2
3
1
ai
Asphalt Concrete (BM-25.OA or D) 1
A.C.
1.67
2.5
4
Multiple6
Full Depth Asphalt Concrete (BM-25.OA or
A.C.
2.15 **
2.5
4
Multiple
D) over Subgrade'
Untreated Aggregate 5
Agg.
1.00
See Notes
Cement Treated Aggregate
CTA
1.67
Cement Treated Select Material, Type II6
Sel. Mat. C
1.50
Multiple6
min. CBR = 20
Base a2
Select Material Type I & II, non -plastics, min.
Sel. Mat.
0.84
CBR = 30
6
10
See Notes
Select Material, Type II, non -plastics, min.
Sel. Mat.
0.60
CBR = 20
Soil Cement6
S.C.
1.00
Multiple
Cement Treated Select Material, Type II6
Sel. Mat. C
1.17
Cement Treated Select Borrow
Sel. Bor. C
1.00
Open Graded Drainage Layer
OGDL
0.60
2
3
1
Untreated Aggregate 5
Agg.
0.60
See Notes
Cement Treated Aggregate
CTA
1.33
Multiple
Select Material Type I, non -plastics, min. CBR
Sel. Mat.
0.50
4
10
= 30
See Notes
Select Material Type II, non -plastics, min.
Subbase a3
Sel. Mat.
0.40
CBR = 20
Soil Cement6
S.C.
1.00
Soil Lime
S.L.
0.92
6
8
Multiple
6
Cement Treated Select Material, Type II
Sel. Mat. C
1.17
Cement Treated Select Borrow
Sel. Bor. C
1.00
Appendix IV
Flexible Pavement Design Worksheet for New Subdivision Streets
This sheet is intended for use and submission in conjunction with VDOT's Secondary Street Acceptance Requirements
Municipality
Albemarle Conty
Date: 3/27/2020
Subdivision
Eco Village
Street Name
Road A
Design Engineer
Justin Shimp
Phone: 434.227.5140
AADT Projected traffic for the street segment considered, as defined in the Subdivision Street Requirements.
CBRD Design CBR = Average of CBRT x 2/3 and modified only as discussed in the Pavement Design Guide.
CBRT CBR value of the subgrade sample, taken and tested as specified in the Pavement Design Guide
DME VDOT District Materials Engineer
EPT Equivalent projected traffic
HCV Number of Heavy Commercial Vehicles (e.g. trucks, buses, etc., with 2 or more axles and 6 or more tires).
%HCV Percentage of the total traffic volume composed of Heavy Commercial Vehicles.
RF Resiliency Factor = Relative value of the subgrade soil's ability to withstand repeated loading.
SSV Soil support value of subgrade (SSV = CBRD x RF)
Dp Thickness index of proposed pavement design computed by the Conventional Pavement Design Method
DR Thickness index required, based on Design AADT and SSV, determined by Appendix II.
Step 2: Determine Design Values
Step 1: Determine Design AADT
CBR, RF, and SSV
AADT
281
Sample No. CBRT Resiliency Factor (RF)
1 Source Value
%HCV = 100 (HCV / AADT)
or
3.0%
2 Table 1 1.5
EPT = 20 x HCV
Note: For
3 Appendix I 1.0
Note: For %HCV < 5%, use AADT
%HCV>5%,
r DME approved RF
EPT>AADT
For preliminary designs, use the
lowest RF value in the equation
Design AADT
281
_
CBRD x RF — SSV
Use greater of AADT or EPT
(4.0) x (1.0) = 4.0
Step 3: Pavement Design (Check appropriate box and show proposed pavement design below.)
❑� (A) Limited to Design AADT <_ 400 - Show pavement material notations and thickness }Foul Appendix N Tables A and B.
(B) Show pavement section as developed inthe Pavement Design Guide. DR = 10.3
(See Appendix III for material notations and thickness equivalency values (a)). from Appendix II
Description of Proposed Pavement Section
Material Notation
Thickness, h
a
(a x h)
Surface
SM-9.5A
1.5
2.25
3.38
Base
BM-25.OA
2.5
2.25
5.63
Subbase
VDOT #21A
6.0
0.60
3.60
DP = E(a x h) Dp must equal or exceed the value of DR. = 12.60