B-WIM Axle last distribution on the Swedish Road Network
Sigurdur ErlingssonVTI, Linköping, Sweden
TransportforumLinköping13 - 14 January, 2010
Overview
» M-E design of pavements
» ESAL vs. ALS
» The Swedish BWIM system
» ALS
» Performance Predictions
» LTPP – test structure: Rv31 Nässjö
» Conclusions
M-E performance calculations of pavements
ClimateTraffic
Materials
Structure
Response Time
Damage
Damage AccumulationDistress
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)
The National Sites » 11 locations (always 2 lanes)
» 1 week sampling (2007)
» Limitations» Lane distribution » Tyre pressure» Single wheel vs. Dual wheel» Lateral wander
Axle Load Spectra
Steering axles
Single axles
Tandem axles
Tridem axles
Axle Load Spectra
E4N Mjölby
Steering 10756Single 12780Tandem 10371Tridem 4427Quad 7 38341
0
10
20
30
40
0 50 100 150Axle Weights [kN]
Fre
quen
cy [
%]
Steering
0
5
10
15
0 50 100 150Axle Weights [kN]
Fre
quen
cy [
%]
Single
0
2
4
6
8
10
0 50 100 150 200 250Axle Weights [kN]
Fre
quen
cy [
%]
Tandem
0
2
4
6
8
10
0 50 100 150 200 250 300Axle Weights [kN]
Fre
quen
cy [
%]
Tridem
The National BWIM measurements in 2007
Road Station No. of Axle/vehicle Single/Steering Tandem/Steering Tridem/SteeringType No. Name vehicles
M E4 Torsboda 7150 3.17 0.89 1.19 0.09M E4 Mjölby N 10756 3.56 1.19 0.96 0.41M E4 Mjölby S 8889 3.59 1.17 1.02 0.39M E6 Löddeköping 15436 3.20 1.19 0.62 0.39M E10 Grundträskån 1309 3.55 1.16 1.23 0.15M E14 Torvalla 2120 3.11 1.11 0.94 0.06M E18 Radmansö 3739 3.42 1.23 0.76 0.42M E20 Marieberg 10505 3.60 1.22 1.13 0.25M E65 Skurup 6061 3.13 1.25 0.62 0.27A Rv40 Landvetter W 6591 3.20 1.00 0.83 0.37A Rv40 Landvetter E 7645 3.25 1.12 0.83 0.30A Rv50 Gärdshyttan 6703 3.68 1.42 1.01 0.25A Rv73 Västerhaninge 3165 2.41 1.02 0.35 0.04C Lv373 Storlångträsk 481 3.82 1.03 1.67 0.11
Average 3.33 1.14 0.94 0.25
ALS 2007 – All stations
0
10
20
30
40
0 50 100 150Axle Weights [kN]
Fre
quen
cy [
%]
Steering
0
5
10
15
20
0 50 100 150Axle Weights [kN]
Fre
quen
cy [
%]
Single
0
5
10
15
0 50 100 150 200 250
Axle Weights [kN]
Fre
quen
cy [
%]
Tandem
0
5
10
15
0 50 100 150 200 250 300
Axle Weights [kN]
Fre
quen
cy [
%]
Tridem
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]
Fre
quen
cy [
%]
Steering
0
2
4
6
8
10
0 50 100 150Axle Weights [kN]
Fre
quen
cy [
%]
Single
0
2
4
6
0 50 100 150 200 250Axle Weights [kN]
Fre
quen
cy [
%]
Tandem
0
2
4
6
0 50 100 150 200 250 300Axle Weights [kN]
Fre
quen
cy [
%]
Tridem
Time
Ru
ttin
g
Time
Dam
age
LTPP road - Rv31 Nässjö
8,5
20,0
0,0
Depth [cm]
Sb
BC
AC
70,0
Sg
Rv 31 Nässjö
0
2
4
6
8
10
12
14
16
1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008Date
Rut
[m
m]
Rv31 Nässjö - Mean
Rv31 Nässjö
Mr = 24.643q0.5027
R2 = 0.7174
0
200
400
600
800
1000
0 200 400 600 800 1000
Sum of principal stresses (kPa)
Res
ilie
nt M
odul
us (
MP
a)
Base Course Layer
ALS – Forserum 2005 (Rv-31 Nässjö)
0
10
20
30
40
0 50 100 150Axle Weights [kN]
Fre
quen
cy [
%]
Steering
0
5
10
15
0 50 100 150Axle Weights [kN]
Fre
quen
cy [
%]
Single
0
5
10
15
0 50 100 150 200 250Axle Weights [kN]
Fre
quen
cy [
%]
Tandem
0
2
4
6
8
10
0 50 100 150 200 250 300Axle Weights [kN]
Fre
quen
cy [
%]
Tridem
0
2
4
6
8
0 2 4 6 8 10 12 14 16 18 20 22 24
Hour
Fre
qu
en
cy [
%] Heavy vehicles
Rv31 Forserum 2005
Steering 5613Single 6738Tandem 4278Tridem 703Quad 2 17334
Rv31 – Nässjö performance predictions
0
5
10
15
0 5 10 15 20Time [Year]
Rut
, d [
mm
]
Rut, measurement
Rut, calculations
0
5
10
15
20
0 5 10 15 20
Time [Year]
Cra
ck in
dex
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 has been used to predict the rutting performance of a the LTPP segment on Rv31 Nässjö. Acceptable agreement was observed between measurements and calculations.
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