portorož, slovenia quantifying the impact of jointed concrete pavement curling and warping on...
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![Page 1: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/1.jpg)
Portorož, Slovenia
Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness
•George Chang, PhD, PEGeorge Chang, PhD, PE
•Transtec GroupTranstec Group
•Project ManagerProject Manager
•[email protected]@theTranstecGroup.com
T H ETRANSTEC GROUPTHE
![Page 2: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/2.jpg)
Portorož, Slovenia
US FHWA Curl/Warp Study
o Impact of Curling and Warping on JCP Performance
![Page 3: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/3.jpg)
Portorož, Slovenia
Outlines
o Curl/Warp Measurement o Profile Synchronization and Joint
IDo 2GCI Curvature Indexo RoCK System for Curvature-
Impact-Roughess Analysis
![Page 4: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/4.jpg)
Portorož, Slovenia
Curl/Warp Measurement
o What to be measured?• Site Selection• Data Collection
o How to measure?• Profiling• Temperature• Others
![Page 5: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/5.jpg)
Portorož, SloveniaSeasonal SiteNon-seasonal Site
Selected Sites
Dry-Freeze
Wet-NonfreezeDry-Nonfreeze
Wet-Freeze
![Page 6: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/6.jpg)
Portorož, Slovenia
Diurnal Profiling
-1
-0.5
0
0.5
1
1.5
2
2.5
12:00 PM 4:00 PM 8:00 PM 12:00 AM 4:00 AM 8:00 AM 12:00 PM 4:00 PM
Time of Day
Tem
per
atu
re G
rad
ien
t (d
eg F
/in
ch)
Inertial Profiling
-1
-0.5
0
0.5
1
1.5
2
2.5
12:00 PM 4:00 PM 8:00 PM 12:00 AM 4:00 AM 8:00 AM 12:00 PM 4:00 PM
Time of Day
Tem
per
atu
re G
rad
ien
t (d
eg F
/in
ch)
Early AM
Mid-AM
Late AM - Early PM
Evening
Critical Passes!!
![Page 7: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/7.jpg)
Portorož, Slovenia
Outlines
o Curl/Warp Measurement o Profile Synchronization and Joint
IDo 2GCI Curvature Indexo RoCK System for Curvature-
Impact-Roughess Analysis
![Page 8: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/8.jpg)
Portorož, Slovenia
Raw Profile
0 50 100 150 200 250 300Distance (m)
-20
-10
0
10
20Left Elevation (mm)
IA_023A
![Page 9: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/9.jpg)
Portorož, Slovenia
Spike Profile
0 50 100 150 200 250 300Distance (m)
-15
-10
-5
0
5
10"Spike" Profile
Filter with moving average anti-smoothingNormalize by RMSSearch deepest dip by a threshold
![Page 10: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/10.jpg)
Portorož, Slovenia
Spike Incidence
0 50 100 150 200 250 300Distance (m)
100
80
40
20
0Spike Incidence (percent)
Assemble the dip count across the data set
![Page 11: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/11.jpg)
Portorož, Slovenia
Weeded Spike Incidence
0 50 100 150 200 250 300Distance (m)
80
60
40
20
0Weeded Spike Incidence (percent)
Weed/clear false hitsExtract the joint locations
![Page 12: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/12.jpg)
Portorož, Slovenia
Outlines
o Curl/Warp Measurement o Profile Synchronization and Joint
IDo 2GCI Curvature Indexo RoCK System for Curvature-
Impact-Roughess Analysis
![Page 13: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/13.jpg)
Portorož, Slovenia
Westergaard Curling Formula
2
sinh2
sintanhtan2
cosh2
costanhtan2sinh2sin
coshcos2
l
x
l
x
l
x
l
xzz o
-0.006
-0.004
-0.002
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
-150 -100 -50 0 50 100 150
Distance from Slab Center (inches)
De
fle
cti
on
(in
ch
es
)
-10
0
10
20
30
40
50
60
70
80
90
Str
es
se
s (
ps
i)
Deflection (Modified eq.)(inches)
Transv. Stresses at Top (psi)
![Page 14: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/14.jpg)
Portorož, Slovenia
Adjusted Westergaard Curling Parameters
o Adjusted to overcome Westergaard assumptions
o Fit to actual slab deformationo More fundamental than an arbitrary
geometric functiono Fitted parameters:
• Pseudo-radius of relative stiffness• Pseudo-strain gradient
![Page 15: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/15.jpg)
Portorož, Slovenia
2GCI Fit – Curled Down Slab
25-mm data
![Page 16: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/16.jpg)
Portorož, Slovenia
2GCI Computation
o Isolate the individual slab segmentso De-trend and de-mean the profile
segmento Mask jointso Define model parameterso Perform nonlinear curve fitting
![Page 17: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/17.jpg)
Portorož, Slovenia
2GCI AnalysisAZ_001am - winter
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
20
0 10 20 30 40 50 60 70 80
Slab Number
Pse
ud
o G
rad
ien
t (m
e /cm
)
Early AM Mid AM Noon Late PM
![Page 18: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/18.jpg)
Portorož, Slovenia
2GCI AnalysisAZ_001am - winter
-40
-30
-20
-10
0
10
20
30
40
Early AM Mid AM Noon Late PM
Pse
ud
oG
rad
ien
t D
istr
ibu
tio
n (me /
cm)
Quartile 1
Minimum
Median
Maximum
Quartile 3
![Page 19: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/19.jpg)
Portorož, Slovenia
2GCI AnalysisMN_046a - summer
-20
-10
0
10
20
30
40
50
60
70
0 5 10 15 20 25 30 35
Slab Number
Pse
ud
o G
rad
ien
t (m
e /cm
)
Early AM Mid AM Noon Late PM
![Page 20: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/20.jpg)
Portorož, Slovenia
2GCI AnalysisMN_046a - summer
-20
-10
0
10
20
30
40
50
60
70
Early AM Mid AM Noon Late PM
Pse
ud
oG
rad
ien
t D
istr
ibu
tio
n (me /
cm)
Quartile 1
Minimum
Median
Maximum
Quartile 3
![Page 21: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/21.jpg)
Portorož, Slovenia
Mean Curvatures
MN
_044
aN
V_0
47g
NV
_047
hIL
_027
aIL
_029
aU
T_0
58a
MN
_043
aIL
_028
aA
Z_0
02b
IL_0
26a
AZ
_002
aA
Z_0
01a
WA
_060
aC
A_0
08e
NC
_047
cK
S_0
32d
NE
_047
fK
S_0
32c
KS
_032
fM
I_04
0aN
C_0
47d
IA_0
23a
NC
_047
aK
S_0
32e
KS
_038
aO
H_0
50b
OH
_052
bW
I_06
7aO
H_0
52e
NC
_047
bG
A_0
19a
FL_
010a
IA_0
21a
FL_
011a
NE
_047
eN
Y_0
49a
TX
_055
aW
A_0
62a
WA
_062
bM
N_0
44b
OH
_050
cA
Z_0
03a
PA
_053
aK
S_0
38c
WI_
063a
OH
_052
aK
S_0
38b
OH
_052
cO
H_0
52d
FL_
016a
GA
_018
aM
N_0
46a
-40
-30
-20
-10
0
10
20
30
40
Pse
ud
o-g
rad
ien
ts (me
/cm
)
![Page 22: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/22.jpg)
Portorož, Slovenia
Outlines
o Curl/Warp Measurement o Profile Synchronization and Joint
IDo 2GCI Curvature Indexo RoCK System for Curvature-
Impact-Roughess Analysis
![Page 23: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/23.jpg)
Portorož, Slovenia
2GCI vs RoughnessAZ_001m
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
0:00 4:48 9:36 14:24 19:12 0:00
Time
HR
I (m
/km
) Spring
Summer
Fall
Winter
![Page 24: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/24.jpg)
Portorož, Slovenia
2GCI vs RoughnessAZ_001m
-16
-14
-12
-10
-8
-6
-4
-2
0
0:00 4:48 9:36 14:24 19:12 0:00
Time
Me
an
Ps
eu
do
-Gra
die
nt
(me /
cm
)
Spring
Summer
Fall
Winter
![Page 25: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/25.jpg)
Portorož, Slovenia
2GCI vs RoughnessAZ_001m
0.6
0.8
1
1.2
1.4
1.6
1.8
-16 -14 -12 -10 -8 -6 -4
Mean Pseudo-gradient (me/cm)
HR
I (m
/km
) Spring
Summer
Fall
Winter
![Page 26: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/26.jpg)
Portorož, Slovenia
Roughness
Curvature (downward)
Curvature (upward)
0CrtClf
Rub
Rlb
Rzc
The RoCK Chart
![Page 27: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/27.jpg)
Portorož, Slovenia0
Rub
Rlb
Rzc
Rbtc
Curvature-related Roughness
Non Curvature-related Roughness
Roughness DecompositionRoughness Decomposition
![Page 28: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/28.jpg)
Portorož, Slovenia
Roughness
Curvature (downward)
Curvature (upward)
0CrtClf
Rub
Rlb
Rzc
TYPE I-A Sites
Curled upCurvature dominates
roughness
Src < 0Rbtc > 0
![Page 29: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/29.jpg)
Portorož, Slovenia
Roughness
Curvature (downward)
Curvature (upward)
0CrtClf
Rub
RlbRzc
TYPE I-B Sites
Curled up mildlyCurvature affects
roughness
Src < 0Rbtc ~ 0
![Page 30: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/30.jpg)
Portorož, Slovenia
Roughness
Curvature (downward)
Curvature (upward)
0CrtClf
Rub
RlbRzc
TYPE II SitesCurled up and downCurvature affects Roughness mildly
Src < 0Rbtc ~ 0
Src > 0Rbtc ~ 0
![Page 31: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/31.jpg)
Portorož, Slovenia
Roughness
Curvature (downward)
Curvature (upward)
0 CrtClf
Rub
Rlb
Rzc
TYPE III-A Sites
Curled downCurvature dominates
roughnessSrc > 0Rbtc > 0
![Page 32: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/32.jpg)
Portorož, Slovenia
Roughness
Curvature (downward)
Curvature (upward)
0CrtClf
Rub
RlbRzc
TYPE III-B Sites
Curled down mildlyCurvature affects
roughness
Src > 0Rbtc ~ 0
![Page 33: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/33.jpg)
Portorož, Slovenia
Bolivian Project
o Two-lane undivided JCPo Mountainous terrain with moderate fills
and cutso 24-ft wide, 12-ft joint spacingo 8-inch slab on 6-inch granular baseo Local climate is arid with rains from
December to Marcho Drastic overnight temperature drops
![Page 34: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/34.jpg)
Portorož, Slovenia
Bolivian Project
o Low relative humidity and extreme temperatures
o Mix with a relatively high water cement ratio, high CTE aggregate, and inadequate curing techniques.
o Longitudinal cracks at the center of the slab in both travel directions after the first winter
![Page 35: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/35.jpg)
Portorož, Slovenia
Bolivian Project-300
-200
-100
0
100
200
300
PT
Ca
ma
rgo
PT
Isc
aya
chi-1
PT
Cie
ne
gu
illa
s
PT
El P
ue
nte
PT
Circ
un
vala
cio
n
AH
-1
AH
-2
AH
-3
Oru
ro-T
ole
do
Cot
ap
ata
Sta
. B
arb
ara
Pte
. S
acr
am
en
to
Sa
n J
osé
-Ro
bo
ré
Pavement SectionP
seu
do
-gra
die
nt
(me /
in.)
Quartile 1
Minimum
Median
Maximum
Quartile 3
AM
![Page 36: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/36.jpg)
Portorož, Slovenia
Bolivian Project
![Page 37: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/37.jpg)
Portorož, Slovenia
Bolivian Project
Effect of curling and loading-current geometry
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
Legal limit loadonly
Loading on 28Ton tandem only
Curling + legalload
Curling + loadon 28 ton tandem
curling + load on20 Ton simple
axle
Str
esses (
Kp
a)
Strength
FEM Analysis
![Page 38: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/38.jpg)
Portorož, Slovenia
The Implications…
o What’s timing to measure roughness for a pavement acceptance testing?
o What’s the best practice to avoid curl and warp?
o What’s the best time to grind the pavements to improve smoothness?
![Page 39: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/39.jpg)
Portorož, Slovenia
Tools you can use…
o New, robust profile synchronization and joint identification techniques
o Invention of 2GCI to better characterize slab curvature
o New, effective slab curvature analysis framework
o RoCK System to assess curvature’s impact on roughness
![Page 40: Portorož, Slovenia Quantifying the Impact of Jointed Concrete Pavement Curling and Warping on Pavement Unevenness George Chang, PhD, PEGeorge Chang, PhD,](https://reader030.vdocuments.net/reader030/viewer/2022032517/56649cbb5503460f949839e2/html5/thumbnails/40.jpg)
Portorož, Slovenia
Acknowledgement
o US FHWA Sponsorshipo Co-authors:
• Steven M. Karamihas, University of Michigan, USA• Robert Otto Rasmussen, P.E., Ph.D., The Transtec Group,
Inc., USA• David Merritt, P.E., M.S., The Transtec Group, Inc., USA• Mark Swanlund, P.E., US DOT Federal Highway
Administration, USA
o Many US State DOT for assistance in field measurements