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HVS Program update: GPGRT and CSIR

Louw du Plessis

HVSIA 31 Aug - 2 Sept 2015

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Contents

• HVS related progress • SIM feedback • Manual Visual Condition Index vs automatic data capturing with

instrumented vehicles

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HVS feedback

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Manual Visual Condition Index vs automatic data capturing with instrumented vehicles

• Brief description of how Visual Condition Index (VCI) is measured and calculated (surfaced Pavements)

• Brief description of how Overall Condition Index (OCI) is measured and calculated

• GPDRT VCI data (2010) • Sample of SANRAL OCI data (2013) • Evaluation of differences

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Measure all visual distress and rate it on a scale of 1 to 5 in terms of degree and extent (structural and functional properties)

• Surfacing defects examples – Spalling of reseal or overlays around cracks (spalling is defined

as the crumbling away of surfacing material around cracks); – Localised loss of surfacing owing to poor bonding with the

underlying layer; – Disintegration of weak aggregates; and – Distress owing to salt damage to the surfacing.

• Structural failures • Functional failures

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Structural properties

– Structural Cracking – Pumping – Deformation:

• Rutting • Undulation/Settlement

– Patching – Failures / potholes

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Functional properties

• Riding Quality – potholes/failures; – Patching; – undulations; – corrugation; and – general unevenness.

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Functional properties

• Skid Resistance – Bleeding – Polished aggregates – Drainage

• Untraveled way – Shoulder erosion – Level differences – Shoulder slope (too steep) – etc.

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Field Assessment Form

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Field Assessment Form

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Data analysis: TMH 22

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Calculation of VCI for flexible paved roads

The calculation of the visual condition index requires the selection of a weighting factor for each type of distress. The formulae for calculating the VCI are given in equations below.

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Get this from the field form

Get this from the field form

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Factor C

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Calculation of VCI for flexible paved roads

Ratio of the current condition over the worst condition

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Example

If current condition Σ Fn = 40 and worst condition Σ Fn = 50, then VCI = 100 ( 1 – 0.02 x 40) = 20 (bad) If current condition Σ Fn = 10(good) and worst condition Σ Fn = 50, then VCI = 100 ( 1 – 0.02 x 10) = 80 (Good)

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Conversion required to get VCI to a % scale

VCI calculations (GPDRT 2010 data set)

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Overall Condition Index (OCI) from automated data capturing using instrumented vehicles

• OVI is a function of: – Riding quality – Rut depth – Surface texture – Structural Stiffness Index – Crack Index (Formula developed in-house by SANRAL. Not in any TMH or TRH yet)

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OCI calculated for each 100m of road network measured

• OCI = a*IRI + b*RUT + c*Text + d*SSI + e*Crack – IRI: International Roughness index value – Rut: Rut depth Index value – Text: Macro Texture Index value – SSI: Structural Stiffness Index value calculated from FWD

data – Crack: Crack index

All parameters are measured by SANRAL’s automated vehicle except SSI

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a – e: weight coefficients

SSI is determined through FWD testing

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Ymax & BLI

• Determined from FWD testing: – Ymax: max deflection under FWD load plate (d0) – BLI = Deflection originating from the base layer

calculated as: d0 – d300 • D300 is the deflection measured by the sensor placed

300mm away from the dropping load plate

FALLING WEIGHT DEFLECTOMETER (FWD): Ymax & BLI

d0

BLI = d0 - d300

300mm

d300

Ymax

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FWD output example

d0 d300 BLI = d0 - d300

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Structural Stiffness Index (SSI) (TRH 22 – 1994)

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X = Lymax, LBLI

The Pavement base coarse types comes from the Province material data base. Is there an existing one? Can we assume that all surfaced roads have Granular base coarse material?

• E = ADT x % heavy Veh x # 80s/ heavy Veh

Issues: ADT per lane 12h counts convert to ADT, How many E80s/ truck (I used 2)

• We get this from looking at the traffic growth over a period (Use growth over the last 5 years ?) (for my examples I used 3%)

We get this from Traffic volume counts

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Final SSI

• The final SSI value is the average of the SSI values determined from Ymax and BLI measurements

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Summary SSI flow diagram

LINEAR_ SECTIODIRECTPROVIOWNER BEGIN_DIST END_DIST LANE IRI RUT TEXT SSI OCID025 1 N 5 PROV 0.00000 0.10000 1 0.00000 0.80922 1.00000 0.75000 59.27665 D025 1 N 5 PROV 0.10000 0.20000 1 0.73724 0.88945 0.34918 0.75000 70.78459 D025 1 N 5 PROV 0.20000 0.30000 1 0.96009 0.87968 0.88341 0.75000 87.86147 D025 1 N 5 PROV 0.30000 0.40000 1 0.87397 0.88770 0.76308 0.75000 83.11162 D025 1 N 5 PROV 0.40000 0.50000 1 0.83741 0.90765 0.63816 0.75000 80.11485 D025 1 N 5 PROV 0.50000 0.60000 1 0.89718 0.86642 1.00000 0.75000 87.90790 D025 1 N 5 PROV 0.60000 0.70000 1 0.83368 0.82955 1.00000 0.75000 84.89697 D025 1 N 5 PROV 0.70000 0.80000 1 0.70813 0.85487 1.00000 0.75000 81.88998 D025 1 N 5 PROV 0.80000 0.90000 1 0.48301 0.83496 1.00000 0.75000 74.53885 D025 1 N 5 PROV 0.90000 1.00000 1 0.81106 0.81339 1.00000 0.75000 83.73361 D025 1 N 5 PROV 1.00000 1.10000 1 0.84223 0.86696 1.00000 0.75000 86.27570 D025 1 N 5 PROV 1.10000 1.20000 1 0.65913 0.87527 1.00000 0.75000 81.03214 D025 1 N 5 PROV 1.20000 1.30000 1 0.73467 0.78907 1.00000 0.75000 80.71220 D025 1 N 5 PROV 1.30000 1.40000 1 0.77255 0.77736 1.00000 0.75000 81.49735 D025 1 N 5 PROV 1.40000 1.50000 1 0.78079 0.82270 1.00000 0.75000 83.10464 D025 1 N 5 PROV 1.50000 1.60000 1 0.61679 0.81359 1.00000 0.75000 77.91150 D025 1 N 5 PROV 1.60000 1.70000 1 0.86757 0.84208 1.00000 0.75000 86.28922 D025 1 N 5 PROV 1.70000 1.80000 1 0.87942 0.84611 1.00000 0.75000 86.76569 D025 1 N 5 PROV 1.80000 1.90000 1 0.57362 0.87830 1.00000 0.75000 78.55753 D025 1 N 5 PROV 1.90000 2.00000 1 0.80492 0.87230 1.00000 0.75000 85.31668 D025 1 N 5 PROV 2.00000 2.10000 1 0.92578 0.86768 1.00000 0.75000 88.80385 D025 1 N 5 PROV 2.10000 2.20000 1 0.75975 0.82067 1.00000 0.75000 82.41242 D025 1 N 5 PROV 2.20000 2.30000 1 0.89461 0.85204 1.00000 0.75000 87.39960

Example of data from SANRAL (2013)

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Comparisons: Road K175

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Comparisons: Road K175

Traffic 2013:

K175:Hand 2013 12h: 7 297 22% Sec 1

106 29% Sec 21 970 22% Sec 35 178 20% Sec 4

ADT current % Heavies #80s/ Heavy # lanes Equiv daily E80sConveted to ADTHand 2013 24h: 10 946 22 2 1 4816 Sec 1

159 29 2 1 92 Sec 22 955 22 2 1 1300 Sec 33 910 20.00 2 1 1564 Sec 4

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K175: FWD data

K175 1 A 0.071 0.2 0.271 569.65 385K175 1 A 0.271 0.201 0.472 413.1 161.65K175 1 A 0.472 0.2 0.672 479.2 288.1K175 1 A 0.672 0.199 0.871 461.2 267.15K175 1 A 0.871 0.201 1.072 707.35 471.45K175 1 A 1.072 0.199 1.271 733.25 471.85K175 1 A 1.271 0.201 1.472 590.55 367.85K175 1 A 1.472 0.199 1.671 485.75 306.05K175 1 A 1.671 0.2 1.871 666.35 442.15K175 1 A 1.871 0.2 2.071 564.4 387.85K175 1 A 2.071 0.201 2.272 536.2 288.05K175 1 A 2.272 0.199 2.471 600 397.45K175 1 A 2.471 0.201 2.672 433.95 262.2K175 1 A 2.672 0.2 2.872 266.15 158.3K175 1 A 2.872 0.2 3.072 487.35 331.6K175 1 A 3.072 0.2 3.272 468.2 311.95K175 1 A 3.272 0.2 3.472 617.4 400.35K175 1 A 3.472 0.199 3.671 347.65 227.7

Linear_IDSection_I

DDirection

Starting_Distance

Distance_between_drops

Up_to_Distance

Average_Y_Max

Average_BLI

Weak

Strong

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K175: Results: OCI vs VCI

K175Sec 1 OCI VCI

2010Mean 62 84 Cat Road

0.95 69 A0.90 69 B0.80 67 C

Sec 2Mean 69 85 Cat Road

0.95 74 A0.90 73 B0.80 72 C

Sec 3Mean 56 55 Cat Road

0.95 77 A0.90 71 B0.80 63 C

Sec 4Mean 65 77 Cat Road

0.950 76 A0.900 74 B0.800 71 C

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D25

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D25Sec 1 OCI VCI

2010Mean 72 78 Cat Road

95% 77 A90% 76 B80% 75 C

Sec 2Mean 65 91 Cat Road

95% 75 A90% 75 B80% 69 C

Sec 3Mean 65 87 Cat Road

0.95 71 A0.9 70 B0.8 69 C

D30Sec 1 OCI VCI

2010Mean 44.6 68 Cat Road

ABC

Sec 2 Cat RoadMean 55 47 A

0.95 68 B0.9 64 C0.8 62

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Comparison

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10

20

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40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Visu

al C

ondi

tion

Inde

x

Overall Condition Index

VCI vs OCI

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69

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65

72

65

65

45

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K175

D25

D30

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Why should we calculate both VCI and OCI ?

• They measure different properties and are not directly related to each other. • For instance with the FWD we measure the structural capacity of a

pavement (remaining life) something we cannot measure with visual surveys only.

• Example:

– If a fog spray is applied to an old pavement surface and new line markings, the VCI can increase from below 60 to above 80.

– Using the OCI method the application of a fog spay (covering the surface distress) will not mask the problem and will have no impact on the OCI values

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Thank you