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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
This report is an archived publication and may contain dated technical, contact, and link information |
|
Publication Number: FHWA-HRT-01-167 Date: April 2005 |
The first step in the evaluation of the SPS-2 experiment is to assess how much of the original experiment was actually constructed and what effect missing sites will have on obtaining expected findings. The original SPS-2 experiment design, the SPS-2 experimental sites actually constructed, the effects of blank experimental design cells, and potential information available from the SPS-2 supplemental sites are discussed in this chapter.
The complete experiment design factorial, the site classification category, and individual section identification numbers are given in table 1. This design factorial requires a total of 16 SPS-2 sites and 192 core sections be evenly distributed within the factorial matrix of climate and subgrade to satisfy the requirement of the SPS-2 experiment design.
The experiment design for SPS-2 included eight main factors. Three are project site factors, and the remaining five are related to the pavement structure.
Project Site Factors
Three factors describe site conditions at the test site:
Traffic loading was incorporated as a covariant. Each of the SPS-2 sites required a relatively high rate of traffic of at least 200,000 rigid equivalent single-axle loads (ESALs) per year.
The experiment design factorial at the project site level is provided in table 2. The design factorial calls for a total of 16 SPS-2 sites to be constructed throughout the United States.
Pavement Structure Design Factors
In addition to the three site factors, five experiment design factors were allocated to the pavement structure. Two factors were allocated to the surface layer: one for thickness and one for strength. Two other structural factors were allocated to the base/subbase: one for strength/stability and the other for drainage. The last factor was assigned to the width of the pavement slab. In summary, the SPS-2 experiment incorporates the following pavement structural factors:
Table 1. Original SPS-2 experiment design.
Pavement Structure |
SPS-2 Site Designation |
|||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
J |
K |
L |
M |
N |
O |
P |
Q |
R |
S |
T |
U |
V |
W |
X |
Y |
|||||
Edge Drain |
Base Type |
PCC |
Lane Width, m |
Climate Zones, Subgrade |
||||||||||||||||
Wet |
Dry |
|||||||||||||||||||
Thick mm |
Strength MPa |
Freeze |
No-Freeze |
Freeze |
No-Freeze |
|||||||||||||||
Fine |
Coarse |
Fine |
Coarse |
Fine |
Coarse |
Fine |
Coarse |
|||||||||||||
No |
AGG |
203 |
3.8 |
3.66 |
01 |
01 |
01 |
01 |
01 |
01 |
01 |
01 |
||||||||
4.27 |
13 |
13 |
13 |
13 |
13 |
13 |
13 |
13 |
||||||||||||
6.2 |
3.66 |
14 |
14 |
14 |
14 |
14 |
14 |
14 |
14 |
|||||||||||
4.27 |
02 |
02 |
02 |
02 |
02 |
02 |
02 |
02 |
||||||||||||
279 |
3.8 |
3.66 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
15 |
||||||||||
4.27 |
03 |
03 |
03 |
03 |
03 |
03 |
03 |
03 |
||||||||||||
6.2 |
3.66 |
04 |
04 |
04 |
04 |
04 |
04 |
04 |
04 |
|||||||||||
4.27 |
16 |
16 |
16 |
16 |
16 |
16 |
16 |
16 |
||||||||||||
No |
LCB |
203 |
3.8 |
3.66 |
05 |
05 |
05 |
05 |
05 |
05 |
05 |
05 |
||||||||
4.27 |
17 |
17 |
17 |
17 |
17 |
17 |
17 |
17 |
||||||||||||
6.2 |
3.66 |
18 |
18 |
18 |
18 |
18 |
18 |
18 |
18 |
|||||||||||
4.27 |
06 |
06 |
06 |
06 |
06 |
06 |
06 |
06 |
||||||||||||
279 |
3.8 |
3.66 |
19 |
19 |
19 |
19 |
19 |
19 |
19 |
19 |
||||||||||
4.27 |
07 |
07 |
07 |
07 |
07 |
07 |
07 |
07 |
||||||||||||
6.2 |
3.66 |
08 |
08 |
08 |
08 |
08 |
08 |
08 |
08 |
|||||||||||
4.27 |
20 |
20 |
20 |
20 |
20 |
20 |
20 |
20 |
||||||||||||
Yes |
PATB |
203 |
3.8 |
3.66 |
09 |
09 |
09 |
09 |
09 |
09 |
09 |
09 |
||||||||
4.27 |
21 |
21 |
21 |
21 |
21 |
21 |
21 |
21 |
||||||||||||
6.2 |
3.66 |
22 |
22 |
22 |
22 |
22 |
22 |
22 |
22 |
|||||||||||
4.27 |
10 |
10 |
10 |
10 |
10 |
10 |
10 |
10 |
||||||||||||
279 |
3.8 |
3.66 |
23 |
23 |
23 |
23 |
23 |
23 |
23 |
23 |
||||||||||
4.27 |
11 |
11 |
11 |
11 |
11 |
11 |
11 |
11 |
||||||||||||
6.2 |
3.66 |
12 |
12 |
12 |
12 |
12 |
12 |
12 |
12 |
|||||||||||
4.27 |
24 |
24 |
24 |
24 |
24 |
24 |
24 |
24 |
Notes: Test section numbers included in cells from 01 to 24 represent a full factorial experiment.
AGG = Dense-graded untreated aggregate base.
LCB = Lean concrete base.
PATB = Permeable asphalt-treated base.
Table 2. SPS-2 experiment design-project site factorial.
Subgrade |
Climatic Condition |
|||
---|---|---|---|---|
Wet |
Dry |
|||
Freeze |
No-Freeze |
Freeze |
No-Freeze |
|
Fine |
J |
N |
R |
V |
K |
O |
S |
W |
|
Coarse |
L |
P |
T |
X |
M |
Q |
U |
Y |
Note: Two related sites (e.g., J and K, T and U) make up a full factorial of design features.
The total full factorial designs for combination of the study factors result in 24 different experimental pavement structures (2 thickness x 2 strength x 3 base type x 2 lane width = 24). The experiment design was implemented using a one-half fractional factorial approach that permitted construction of 12 test sections at one site and construction of the 12 complementary sections at another site within the same climatic region and with a similar subgrade type. Both of these complementary sites must be available to evaluate the main effects and all interactions of the design factors within a given climate and subgrade type.
Each SPS-2 test section length is 152 m long. As a result, an SPS-2 project may be constructed over a length greater than 3.2 kilometers (km). Other key design features common to all SPS-2 sections include the following:
At each SPS-2 site, test sections are numbered sequentially either from 01 to 12 or from 13 to 24, depending on climatic and soil type combinations. The numbering within each site depends on the levels of each design factor. Figure 1 graphically presents the section structure and numbering schematic for SPS-2 sections.
Figure 1. Test section details for a full factorial SPS-2 experiment located at two sites (01 to 12 and 13 to 24).
As of August 1999, 13 SPS-2 sites had been constructed throughout the United States An additional site in California had been nominated and may be constructed in the near future. The distribution of the SPS-2 sites is shown on a map in figure 2. The current status of the site design factorial is provided in table 3, showing which State is filling which design cell. As shown in the table, there are five study sites missing from the experiment factorial, indicating a loss of 5 of the 16 (or 31 percent) of the design cells.
Table 3. SPS-2 projects constructed in relation to the project site factorial (note missing cells).
Subgrade |
Climatic Condition |
|||
---|---|---|---|---|
Wet |
Dry |
|||
Freeze |
No-Freeze |
Freeze |
No-Freeze |
|
Fine |
Ohio, Kansas1 (J) |
North Carolina (N) |
? (R) |
? (V) |
Michigan, Iowa (K) |
Arkansas (O) |
North Dakota2 (S) |
? (W) |
|
Coarse |
Delaware (L) |
? (P) |
Nevada, |
California3 (X) |
Wisconsin (M) |
? (Q) |
Colorado (U) |
Arizona (Y) |
Notes: 1 - Kansas site was planned to fill the dry-freeze
zone cell. However, the actual precipitation is quite a bit higher than the
specified annual precipitation for this study.
2 - North Dakota site is slightly wetter than the specified annual precipitation.
3 - California site is currently under construction.
? - Represents a missing SPS-2 project.
A list of all the SPS-2 sections, including both core and supplemental sections, is given in table 4. As shown, many SHAs have constructed additional sections at the SPS-2 sites. These additional sections are not included in the original SPS-2 experiment factorial and are referred to as State supplemental sections. A total of 155 core sections and 40 supplemental sections have been constructed to date. Seven SPS-2 sections are designated as seasonal monitoring program (SMP) sections, where additional sets of climatic and monitoring data are measured.
Table 4. List of constructed SPS-2 core and supplemental sections.
State |
State Code |
Core Sections |
Supplemental Sections |
Seasonal Sections |
|
---|---|---|---|---|---|
ID |
Record Status |
||||
AZ |
04 |
0213-0224 |
E |
0260-0268 (9) |
0215 |
AR |
05 |
0213-0224 |
E |
- |
- |
CO |
08 |
0213-0224 |
E |
0259 |
- |
DE |
10 |
0201-0212 |
E |
0259-0260 (2) |
- |
IA |
19 |
0213-0224 |
E |
0259 |
- |
KS |
20 |
0201-0212 |
E |
0259 |
- |
MI |
26 |
0213-0224 |
E |
0259 |
- |
NV |
32 |
0201-0211 (0212 was removed) |
E |
0259 |
0204 |
NC |
37 |
0201-0212 |
E |
0259-0260 (2) |
0201, 0205, 0208, 0212 |
ND |
38 |
0213-0224 |
E |
0259-0264 (6) |
- |
OH |
39 |
0201-0212 |
E |
0259-0265 (7) |
0204 |
WA |
53 |
0201-0212 |
E |
0259 |
- |
WI |
55 |
0213-0224 |
A |
0259-0266 (8) |
- |
Total number of sections |
155 |
40 |
7 |
The current status of the SPS-2 experiment design, showing constructed sections in relation to the original experiment design, is given in table 5. The following five sites (columns) are missing from the original experiment design:
Pavement Structure |
Climate Zones, Subgrade, Site |
||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Wet |
Dry |
||||||||||||||||||
Base Type/ Edge Drain |
PCC |
Lane Width m |
Freeze |
No-Freeze |
Freeze |
No-Freeze |
|||||||||||||
Thick mm |
Flexural Strength MPa |
Fine |
Coarse |
Fine |
Coarse |
Fine |
Coarse |
Fine |
Coarse |
||||||||||
J |
K |
L |
M |
N |
O |
P |
Q |
R |
S |
T |
U |
V |
W |
X |
Y |
||||
AGG |
203 |
3.8 |
3.66 |
OH, KS |
DE |
NC |
NV, WA |
CA1 |
|||||||||||
4.27 |
MI, IA |
WI |
AR |
ND |
CO |
AZ |
|||||||||||||
6.2 |
3.66 |
MI, IA |
WI |
AR |
ND |
CO |
AZ |
||||||||||||
4.27 |
OH, KS |
DE |
NC |
NV, WA |
CA1 |
||||||||||||||
279 |
3.8 |
3.66 |
MI, IA |
WI |
AR |
ND |
CO |
AZ |
|||||||||||
4.27 |
OH, KS |
DE |
NC |
NV, WA |
CA1 |
||||||||||||||
6.2 |
3.66 |
OH, KS |
DE |
NC |
NV, WA |
CA1 |
|
||||||||||||
4.27 |
MI, IA |
WI |
AR |
ND |
CO |
AZ |
|||||||||||||
LCB |
203 |
3.8 |
3.66 |
OH, KS |
DE |
NC |
NV, WA |
CA1 |
|||||||||||
4.27 |
MI, IA |
WI |
AR |
ND |
CO |
AZ |
|||||||||||||
6.2 |
3.66 |
MI, IA |
WI |
AR |
ND |
CO |
AZ |
||||||||||||
4.27 |
OH, KS |
DE |
NC |
NV, WA |
CA1 |
||||||||||||||
279 |
3.8 |
3.66 |
MI, IA |
WI |
AR |
ND |
CO |
AZ |
|||||||||||
4.27 |
OH, KS |
DE |
NC |
NV, WA |
CA1 |
||||||||||||||
6.2 |
3.66 |
OH, KS |
DE |
NC |
NV, WA |
CA1 |
|||||||||||||
4.27 |
MI, IA |
WI |
AR |
ND |
CO |
AZ |
|||||||||||||
PATB w/ Drain |
203 |
3.8 |
3.66 |
OH, KS |
DE |
NC |
NV, WA |
CA1 |
|||||||||||
4.27 |
MI, IA |
WI |
AR |
ND |
CO |
AZ |
|||||||||||||
6.2 |
3.66 |
MI, IA |
WI |
AR |
ND |
CO |
AZ |
||||||||||||
4.27 |
OH, KS |
DE |
NC |
NV, WA |
CA1 |
||||||||||||||
279 |
3.8 |
3.66 |
MI, IA |
WI |
AR |
ND |
CO |
AZ |
|||||||||||
4.27 |
OH, KS |
DE |
NC |
NV, WA |
CA1 |
||||||||||||||
6.2 |
3.66 |
OH, KS |
DE |
NC |
WA |
CA1 |
|||||||||||||
4.27 |
MI, IA |
WI |
AR |
ND |
CO |
AZ |
Notes: 1 - California site is under construction.
Five additional projects (60 sections total) are needed to complete the design factorial. These missing projects will definitely limit the results obtainable from the SPS-2 experiment, although it is impossible to determine the exact effects at this time. These limitations are summarized as follows:
Some of these deficiencies can be overcome through use of mechanistic analysis of the data. However, there is no mechanistic analysis that considers all factors involved, and the missing cells will always present limitations in the verification and calibration of any performance models.
In addition to the 12 core sections required by the SPS-2 experiment, SHAs can include additional experimental sections, referred to as State supplemental sections. Although there were provisions in the experimental design to study undoweled JPCP and jointed reinforced concrete pavements (JRCP), no such controlled sections have been constructed other than some uncontrolled supplemental sections. Table 6 lists the design variables selected by SHAs for supplemental sections.
The main value of the supplemental sections will be as a direct comparison to the core sections. For example, one supplemental section in Washington did not have dowels; this will provide a direct comparison to a similar design with dowel bars. This comparison is also possible in Arizona and North Dakota. Various other comparisons are also possible, including skewed joints, base types, subdrainage, slab thickness, AC pavement, jointed reinforced concrete, special dowels, and variable slab thickness.
Table 6. List of the constructed SPS-2 State supplemental sections and designs.
State |
SHRP ID |
Pavement Design Description |
---|---|---|
AZ |
0260 |
216 mm dense-graded AC on 102 mm DGAB. |
0261 |
216 mm dense-graded AC on 102 mm DGAB. |
|
0262 |
203 mm undoweled JPC (3.8 MPa Resilient Modulus (MR)) on DGAB and 4.27 m lane. |
|
0263 |
203 mm undoweled JPC (3.8 MPa MR) on PATB and DGAB and 4.27 m lane. |
|
0264 |
279 mm undoweled JPC (3.8 MPa MR) on PATB and DGAB and 3.66 m lane. |
|
0265 |
279 mm undoweled JPC (3.8 MPa MR) on DGAB and 3.66 m lane. |
|
0266 |
318 mm doweled JPC (3.8 MPa MR) on bituminous treated base (BTB) and 4.27 m lane. |
|
0267 |
279 mm doweled JPC (3.8 MPa MR) on BTB and 4.27 m lane. |
|
0268 |
203 mm doweled JPC (3.8 MPa MR) on BTB and 4.27 m lane. |
|
CO |
0259 |
279 mm JPC (4.5 MPa) on subgrade and 3.66 m lanes. |
DE |
0259 |
254 mm JPC (20.7 MPa f'c) on 203 mm DGAB; 3.66 m lane; steel dowels. |
0260 |
254 mm JPC (20.7 MPa f'c) on 203 mm DGAB; 3.66 m lane; plastic dowels. |
|
IA |
0259 |
279 mm JPC; 4.27 m wide lane. |
KS |
0259 |
305 mm doweled JPC (4.1-MPa mix) on 152 mm stabilized subbase on 152 mm modified flyash subgrade and 3.66 m lane. |
MI |
0259 |
267 mm JRC on 102 mm open-graded base course (OGBC) on 76 mm aggregate base. |
NV |
0259 |
267 mm JPC on 38 mm leveling course, 27.6 MPa +- 20% 14-day compressive strength. |
NC |
0259 |
254 mm JPC on 102 mm PATB on 25.4 mm AC on 203-mm lime-stabilized subgrade. |
0260 |
279 mm JPC on 25.4 mm AC on 127 mm BTB on 203-mm cement-treated subgrade. |
|
ND |
0259 |
254 mm doweled JPC (ND mix) on 203 mm salve with skewed joints and 3.66 m lanes. |
0260 |
279 mm doweled JPC (ND mix) on DGAB with skewed joints and 4.27 m lanes. |
|
0261 |
279 mm undoweled JPC (3.8 MPa MR) on DGAB with skewed joints and 3.66 m lanes. |
|
0262 |
279 mm undoweled JPC on LCB with skewed joints (various lengths) and 4.27 m lanes. |
|
0263 |
279 mm undoweled JPC on PATB with random skewed joints and 3.66 m lanes. |
|
0264 |
279 mm undoweled JPC on PATB with skewed joints and 4.27 m lanes. |
|
OH |
0259 |
279 mm JPC (3.8 MPa MR) on 152 mm DGAB. |
0260 |
279 mm JPC (3.8 MPa MR) on 102 mm PATB on 102 mm DGAB. |
|
0261 |
279 mm JPC (3.8 MPa MR) on 102 mm CTPB on 102 mm DGAB. |
|
0262 |
279 mm JPC on 102 mm CTPB on 102 mm DGAB. |
|
0263 |
279 mm JPC on 152 mm DGAB. |
|
0264 |
279 mm JPC on 152 mm DGAB. |
|
0265 |
279 mm JPC (3.8 MPa MR) on 102 mm PATB on 102 mm DGAB. |
|
WA |
0259 |
Undoweled 254 mm JPC (4.5 MPa MR) on 76 mm ATB on 51 mm crushed surfacing base course; 4.27 m lane. |
WI |
0259 |
279 mm JPC (3.8 MPa MR) on 152 mm DGAB. |
0260 |
279 mm JPC (3.8 MPa MR) on 152 mm DGAB, with alternate dowel bar placement. |
|
0261 |
203 mm JPC (3.8 MPa MR) on 102 mm OGBC on 102 mm DGAB. |
|
0262 |
203 mm JPC (6.3 MPa MR) on 152 mm DGAB, with tied concrete shoulder. |
|
0263 |
203-279 mm JPC (3.8 MPa MR) on 152 mm DGAB, variable pavement thickness. |
|
0264 |
279 mm JPC (3.8 MPa MR) on 152 mm DGAB, with composite dowels. |
|
0265 |
279 mm JPC (3.8 MPa MR) on 152 mm DGAB, with stainless steel dowels. |
|
0266 |
Unknown |
Note: The Arkansas SPS-2 project site does not contain any supplemental sections.