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.