Modellering av vägars beteende – dimensionering och nedbrytning

Sigurdur Erlingsson

TransportforumLinköping8-9 Januari, 2009

Overview» M-E design of pavements» Pavements response and performance » ESAL vs. ALS» BWIM» ALS

» General» Examples» M-E analysis and performance predictions» ALS Comparison

» Conclusions

Mechanistic – Empirical Design

»» MechanisticallyMechanistically calculate pavement response (i.e., stresses, strains, and deflections) due to:» Traffic loading» Environmental conditions

» Accumulate damagedamage over time»» EmpiricallyEmpirically relate damage over time to pavement distresses,

e.g.:» Cracking» Rutting» Faulting» Roughness

»» CalibrateCalibrate (validation) predictions to observed field performance

M-E design of pavements

Climate Traffic

Materials

Structure

ResponseTime

Damage

Damage Accumulation Distress

Design criteria - rutting

10

20

30

40

ESAL vs. ALS» In the ESAL approach all axle loads (different

magnitudes and number) are converted to an Equivalent number of Single Axle Loads based on the EALF representing the relative damage of each axle to the damage of a standard axle.

» In the M-E Design approach truck traffic loadings are given in terms of Axle Load Spectra (ALS). This is a more direct and rational approach for the analysis and design of pavement structures to estimate the effects of actual traffic on pavement response and distress.

The Swedish BWIM system

F(t)

National sites

The National Sites » 12 locations (always 2 lanes)

» 1 week sampling (2007)» No distinction between lanes» Accuracy, errors, gaps, . . .

» Limitations» Lane distribution » Tyre pressure» Single wheel vs. Dual wheel» Lateral wander

The National BWIM measurements in 2007Road Station Name No of Time period No of No of

lanes vehicles axles

E4 Torsboda 1 + 1 2007-08-01 - 2007-08-07 7163 22390

E4N Mjölby 2 2007-04-13 - 2007-04-19 10766 39594

E4S Mjölby 2 2007-04-13 - 2007-04-19 8896 33025

E6N Löddeköping 2 2007-05-09 - 2007-05-15 15448 49795

E6S Löddeköping 2 2007-05-09 - 2007-05-15 16868 53489

E10 Grundträskån 1 + 1 2007-08-23 - 2007-08-30 1179 4223

E14 Torvalla 1 + 1 2007-08-03 - 2007-08-09 2123 6483

E18 Rådmansö 1 + 1 2007-06-21 - 2007-06-27 3739 13165

E20 Marieberg 2 2007-04-12 - 2007-04-19 8661 32861

E65 Skurup 1 + 1 2007-05-23 - 2007-05-29 6061 19266

Rv40W Landvetter 2 2007-05-24 - 2007-05-30 6596 20937

Rv40E Landvetter 2 2007-05-24 - 2007-05-30 7649 24742

Rv50 Gärdshyttan 1 + 1 2007-10-09 - 2007-10-18 6705 25767

Rv73 Västerhaninge 2 2007-09-26 - 2007-10-02 3166 7723

Lv373 Storlångträsk 1 + 1 2006-08-25 - 2006-08-31 674 2593

Art

eria

ltr

un

kC

oun

tyro

adm

otor

way

s

Axle Load Spectra

Steering axles

Single axles

Tandem axles

Tridem axles

Axle Load Spectra

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0 50 100 150Axle Weights [kN]

Freq

uenc

y [%

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Steering

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0 50 100 150Axle Weights [kN]

Freq

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]

Single

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0 50 100 150 200 250Axle Weights [kN]

Freq

uenc

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Tandem

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0 50 100 150 200 250 300Axle Weights [kN]

Freq

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y [%

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Tridem

0

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0 2 4 6 8 10 12 14 16 18 20 22 24Hour

Freq

uenc

y [%

]

Heavy vehicles

E4N Mjölby

Steering 10766Single 12420Tandem 12052Tridem 4356

Σ 39594

Axle Load Spectra

02468

10121416

0 50 100 150Axle Weights [kN]

Freq

uenc

y [%

]

Steering

02468

10121416

0 50 100 150Axle Weights [kN]

Freq

uenc

y [%

]

Single

0

2

4

6

8

0 50 100 150 200 250Axle Weights [kN]

Freq

uenc

y [%

]

Tandem

0

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0 50 100 150 200 250 300Axle Weights [kN]

Freq

uenc

y [%

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Tridem

0

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0 2 4 6 8 10 12 14 16 18 20 22 24Hour

Freq

uenc

y [%

]

Heavy vehicles

Lv373 Storlångträsk

Steering 674Single 466Tandem 1431Tridem 22

Σ 2593

0

5

10

15

20

25

0 20 40 60 80 100 120

Axle Weights [kN]

Freq

uenc

y [%

]

E10 GrundträskånE14 TorvallaE18 RådmansöE20 MariebergE4 TorsbodaE4N MjölbyE4S MjölbyE65 SkurupE6N LöddeköpingE6S LöddeköpingLv373 StorlångsträkRv40W LandvetterRv40E LandvetterRv50 GärdshyttanRv73 Våsterhaninge

Steering

0

4

8

12

16

0 20 40 60 80 100 120

Axle Weights [kN]

Freq

uenc

y [%

]

Single

ALS 2007 – All stations

0

2

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6

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0 50 100 150 200 250

Axle Weights [kN]

Freq

uenc

y [%

]

Tandem

0

2

4

6

8

10

0 50 100 150 200 250 300

Axle Weights [kN]

Freq

uenc

y [%

]

Tridem0

2

4

6

8

10

12

14

16

0 3 6 9 12 15 18 21 24

Hour

Freq

uenc

y [%

]

ALS – PredictionStation No of No of Ratio Singles/Steering Tandem/Steering Tridem/Steering

Road Name vehicles axles Axle/vehicle

E4 Torsboda 7163 22390 3.13 0.84 1.20 0.09

E4N Mjölby 10766 39594 3.68 1.15 1.12 0.40

E4S Mjölby 8896 33025 3.71 1.13 1.19 0.39

E6N Löddeköping 15448 49795 3.22 1.17 0.67 0.38

E6S Löddeköping 16868 53489 3.17 1.11 0.67 0.40

E10 Grundträskån 1179 4223 3.58 1.09 1.36 0.13

E14 Torvalla 2123 6483 3.05 1.02 0.98 0.05

E18 Rådmansö 3739 13165 3.52 1.23 0.87 0.42

E20 Marieberg 8661 32861 3.79 1.18 1.37 0.24

E65 Skurup 6061 19266 3.18 1.23 0.68 0.26

Rv40W Landvetter 6596 20937 3.17 0.94 0.89 0.35

Rv40E Landvetter 7649 24742 3.23 1.05 0.90 0.28

Rv50 Gärdshyttan 6705 25767 3.84 1.39 1.20 0.25

Rv73 Västerhaninge 3166 7723 2.44 1.01 0.39 0.04

0.03Lv373 Storlångträsk 674 2593 3.85 0.69 2.12

Average 1.13 0.96 0.23

Performance Predictions and ALS

Time, years

Traffic

Granular Base Modulus

Each load application

2 8640

Subgrade Modulus

AC Modulus

0

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0 50 100 150Axle Weights [kN]

Freq

uenc

y [%

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Steering

0

2

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0 50 100 150Axle Weights [kN]

Freq

uenc

y [%

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Single

0

2

4

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0 50 100 150 200 250Axle Weights [kN]

Freq

uenc

y [%

]

Tandem

0

2

4

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0 50 100 150 200 250 300Axle Weights [kN]

Freq

uenc

y [%

]

Tridem

Time

Rut

ting

Time

Dam

age

ALS - Comparison

0

5

10

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25

0 50 100 150Axle Weights [kN]

Freq

uenc

y [%

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Steering

0

2

4

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0 50 100 150Axle Weights [kN]

Freq

uenc

y [%

]Single

0

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0 50 100 150 200 250Axle Weights [kN]

Freq

uenc

y [%

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Tandem

0

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0 50 100 150 200 250 300Axle Weights [kN]

Freq

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]

Tridem

Highway 5Redding, CAUSA

Motorway E4NMjölbySweden

Conclusions» The M-E Pavement design method represent a major

change in the way pavement design is performed.» With the M-E design the performance of pavements can

be estimated. » In M-E design of pavements Axle Load Spectra is used to

characterise the heavy traffic loading. » A more comprehensive data sampling and analyses of

ALS is needed in Sweden if M-E pavement design will be used in the future.

» ALS’s from USA(CA) are probably not representative for Swedish conditions.