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
0
5
10
15
20
25
0 50 100 150Axle Weights [kN]
Freq
uenc
y [%
]
Steering
0
2
4
6
8
10
0 50 100 150Axle Weights [kN]
Freq
uenc
y [%
]
Single
0
2
4
6
0 50 100 150 200 250Axle Weights [kN]
Freq
uenc
y [%
]
Tandem
0
2
4
6
0 50 100 150 200 250 300Axle Weights [kN]
Freq
uenc
y [%
]
Tridem
0
2
4
6
8
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
5
10
15
20
25
0 50 100 150 200 250 300Axle Weights [kN]
Freq
uenc
y [%
]
Tridem
0
2
4
6
8
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
4
6
8
10
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
5
10
15
20
25
0 50 100 150Axle Weights [kN]
Freq
uenc
y [%
]
Steering
0
2
4
6
8
10
0 50 100 150Axle Weights [kN]
Freq
uenc
y [%
]
Single
0
2
4
6
0 50 100 150 200 250Axle Weights [kN]
Freq
uenc
y [%
]
Tandem
0
2
4
6
0 50 100 150 200 250 300Axle Weights [kN]
Freq
uenc
y [%
]
Tridem
Time
Rut
ting
Time
Dam
age
ALS - Comparison
0
5
10
15
20
25
0 50 100 150Axle Weights [kN]
Freq
uenc
y [%
]
Steering
0
2
4
6
8
10
0 50 100 150Axle Weights [kN]
Freq
uenc
y [%
]Single
0
2
4
6
0 50 100 150 200 250Axle Weights [kN]
Freq
uenc
y [%
]
Tandem
0
2
4
6
0 50 100 150 200 250 300Axle Weights [kN]
Freq
uenc
y [%
]
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.
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