characterizing traffic for rigid pavements in illinois

Characterizing Traffic for Rigid Pavements in IllinoisJeffery Roesler, Ph.D., P.E.Associate ProfessorDepartment of Civil and Environmental EngineeringUniversity of Illinois

North Central M-EPDG User’s Group MeetingAmes, IAFebruary 19-20, 2008

Acknowledgements

ICT R57 – Technical Review Panel

Illinois Department of Transportation

Amy Schutzbach et al.

UIUC Students

Jake Hiller

Dong Wang

Victor Cervantes

Matt Beyer

Amanda Bordelon

Overview

Illinois has existing M-E JPCP method by Zollinger and Barenberg (1989)

ESALs

IDOT has an empirical method to determine CRCP thickness

ESALs

Update/refine existing JPCP procedure and develop M-E CRCP design method

M-EPDG Evaluation

Traffic Objective

Evaluate version 0.91 vs. 1.0

Determine effects of traffic distributions on rigid pavement design

Traffic Questions

How does load spectra affect thickness design of concrete?

Is load spectra necessary over ESALs?

For IDOT, expensive to collect load spectra

Traffic Effects (v. 0.91)

Five different traffic situations

Peoria, IL Control

Standard wheel base distribution

Long Wheelbase

Short Wheelbase

Class 5 – 100% single axles

Class 9 – tandem axles

Traffic Effect –Long Wheelbase

Same inputs as control except for:

Short Medium Long 12 15 18 0% 0% 100%

Wheelbase Truck Tractor

Average Axle Spacing (ft)Percent of trucks

Traffic Effect –Short Wheelbase





Traffic Effect – Inputs Class 5


AADTT set to 7,500 to reach 200x106 ESALs

0.0% 100.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

Vehicle Class Distribution(Level 3, Default Distribution)

AADTT distribution by vehicle classClass 4Class 5Class 6Class 7Class 8Class 9Class 10Class 11Class 12Class 13

0.00 0.00 0.00 0.00 2.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Number of Axles per Truck

Quad Axle

Class 4Class 5Class 6

Vehicle Class

Single Axle

Tandem Axle

Tridem Axle

Class 7Class 8Class 9Class 10Class 11Class 12Class 13




Traffic Effect – Inputs Class 9


AADTT set to 1,100 to reach 200x106 ESALs

Axle load distribution set to 100% at 3000 lbs




0.0% 0.0% 0.0% 0.0% 0.0% 100.0% 0.0% 0.0% 0.0% 0.0%

Vehicle Class Distribution(Level 3, Default Distribution)

AADTT distribution by vehicle classClass 4Class 5Class 6Class 7Class 8Class 9Class 10Class 11Class 12Class 13

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.00 2.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Number of Axles per Truck

Quad Axle

Class 4Class 5Class 6

Vehicle Class

Single Axle

Tandem Axle

Tridem Axle

Class 7Class 8Class 9Class 10Class 11Class 12Class 13

Traffic Effects

Five traffic conditions produce similar results at ~ 200 million ESALs

Cracking vs. Traffic Condition

0

5

10

15

20

Peoria Control Long Wheelbase Short Wheelbase Class 5 Class 9

Traffic Condition

Crac

king

(%)

V.0.91 MEPDG Summary (Feb. 2007)

Vehicle and axle type changes affected design thickness by 0.5 in. only

ESALs appear to give

All cracking is top-down except Class 5 analysis

ESALs vs. Load Spectra Analysis

Axle load distribution effects

Selected Weigh Scales – Illinois

Bolingbrook (North)

Marion (North)

Marion (South)

Moline West

Weigh Stations

Marion (NB & SB)

Pesotum (NB)

Bolingbrook (NB & SB)Frankfort (EB)Moline (EB & WB)

Maryville (WB)

WIM

Vehicle Class DistributionVehicle Class

Bolingbrook (NB)

Bolingbrook (SB)

Frankfort (EB)

Moline (EB)

Moline (WB)

Marion (NB)

Marion (SB)

Maryville (WB)

Pesotum (NB)

4 1.6 1.6 3.7 0.9 1.1 1.1 1.1 1.0 1.8

5 4.6 4.0 1.5 1.3 1.1 2.4 2.7 1.8 6.7

6 3.7 4.0 1.4 2.9 1.8 2.4 2.8 2.1 1.0

7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

8 6.7 6.2 3.0 2.6 2.2 4.1 3.7 2.3 2.7

99 79.079.0 80.180.1 87.587.5 88.888.8 90.490.4 85.285.2 84.084.0 85.985.9 84.384.3

10 0.9 1.0 1.5 0.8 0.7 0.7 1.1 1.2 0.3

11 3.5 2.9 1.2 2.4 2.6 4.1 3.3 4.9 1.8

12 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.2

13 0.0 0.3 0.1 0.2 0.0 0.1 1.2 0.6 0.1

Vehicle Class distributionClass Illinois* California M-EPDGClass 4 1.4% 1.1% 1.8%Class 5 3.8% 23.0% 24.6%Class 6 2.3% 5.2% 7.6%Class 7 0.0% 0.3% 0.5%Class 8 3.8% 6.7% 5.0%Class 9 84.4% 50.6% 31.3%Class 10 0.5% 0.6% 9.8%Class 11 2.8% 8.8% 0.8%Class 12 0.3% 1.1% 3.3%Class 13 0.3% 0.1% 15.3%

TTC11*Close to MEPDG TTC1

Single Axle Distribution

Bolingbrook

Bolinbrook North - Single

0

20

40

60

80

100

120

Under3,001

3,001-7,000

7,001-8,000

8,001-12,000

12,001-16,000

16,001-18,000

18,001-19,000

19,001-20,000

20,001-22,000

22,001-24,000

24,001-26,000

26,001-30,000

Over30,000

Axle Weight (lbs)

Freq

uenc

y (%

)

Class 4Class 5Class 6Class 7Class 8Class 9Class 10Class 11Class 12Class 13

Comparison - Axle Weight DistributionClass 9 Tandem Axle Weight Distribution

0

2

4

6

8

10

12

14

6000

1000

014

000

1800

022

000

2600

030

000

3400

038

000

4200

046

000

5000

054

000

Axle Weight (lbs)

Freq

uenc

y (%

)

ME-PDGBolingbrook NMation SMarion NMoline WPesotum

Class 5 Axle Weight DistributionClass 5 Single Axle Load Distribution

0

10

20

30

40

50

60

70

80

90

Under

3,001

3,001

-7,00

07,0

01-8,

000

8,001

-12,00

012

,001-1

6,000

16,00

1-18,0

0018

,001-1

9,000

19,00

1-20,0

0020

,001-2

2,000

22,00

1-24,0

0024

,001-2

6,000

26,00

1-30,0

00Ove

r 30,0

00

Axle Weight (lbs)

Freq

uenc

y (%

)

ME-PDGBolingbrookPesotum

Class 9 Single Axle Weight distributionClass 9 Axle Weight Distribution

0

10

20

30

40

50

60

70

80

90

100

Under

3,001

3,001

-7,00

07,0

01-8,

000

8,001

-12,00

0

12,00

1-16,0

00

16,00

1-18,0

00

18,00

1-19,0

00

19,00

1-20,0

00

20,00

1-22,0

00

22,00

1-24,0

00

24,00

1-26,0

00

26,00

1-30,0

00Ove

r 30,0

00

Axle Weight (lbs)

Freq

uenc

y (%

)

ME-PDGBolingbrookPesotum

Traffic Cases Analyzed (v. 1.0)

Analyze thickness’ for weigh stations:

MEPDG and Bolingbrook, Moline, Marion (IL)

Replace MEPDG with Bolingbrook data for:

Single axle replacement only

Tandem axle replacement only

Tridem axle replacement only

All axles replaced

M-EPDG Inputs

Slab thickness = 10-inch

4” Asphalt Concrete Base

A-7-6 soil (7,500 psi)

Joint spacing = 15 ft (1.5” dowels)

AC shoulder

Chicago Midway Climate

MOR = 650 psi

Illinois vehicle class distribution (avg.)

JPCP Traffic Assumptions

AADTT values for MEPDG v1.0

20-year design- MEPDG CONTROL112 million ESALs = 12,000 AADTT

*AADTT = Average Annual Daily Truck Traffic

AADTT vs ESALs

Higher AADTT to reach same ESAL count

Illinois has lighter axle weight distribution

0

5000

10000

15000

20000

25000

ME-PDG Bolingbrook Marion S Marion N Moline

AA

DTT

0

20

40

60

80

100

120

140

ESA

Ls

(mill

ion)

ADDTTESALs

Effect of Axle Load Distribution

Effect of axle weight distribution on ESAL count (constant AADTT)

0

20

40

60

80

100

120

ME-PDG Single Tandem Tridem All

ESA

Ls

(mill

ion)

(Bolingbrook)

Percent Cracking at 112x106 ESALs

0

2

4

6

8

1 0

1 2

M E -P D G B o lin g b ro o k M a r io n S M a r io n N M o lin e

Cra

ckin

g Pe

cent

age

(%)

0

2

4

6

8

1 0

1 2

1 4

Thin

knes

s (in

)

P e rc e n t C ra c k in gC o n c re te T h in k n e s s

Similar cracking percentage at 112 million ESALs

9.4 to 10.6%

Description of Overload Cases

Case 1

Class 9 Tandem axle distribution

10% increase distributed between 36-42 kips

Case 2

Class 9 Tandem axle distribution

30% increase at 44 kips

Case 3

Class 5 single axle distribution

10% increase at 30 kips

Case 4

Class 5 single axle distribution

30% at 30 kips and 10 % at 40 kips

(Bolingbrook)

Overload Case

0

2000

4000

6000

8000

10000

12000

1 2 3 4

Overload Case

AA

DTT

0

5

10

15

20

25

30

Perc

ent C

rack

ing

(%)

AADTTCracking %

Constant ESALs =115 MESALs

Dist. Tan.Cl9 30% 44-k Cl5-10%30k

Cl5-30%30k, 10%40k

Overload

Case 4

AADTT = 10,000

ESALs = 115 million

Cracking Percentage = 28.4%

at 95% reliability

Traffic Summary

For existing axle load limits:

ESALs will give reasonable thickness results vs. load spectra for fatigue cracking

Recommend to IDOT to continue with ESALs as traffic input for rigid pavement design.

Load spectra has greater future potential….

Acknowledgements

The Illinois Center for Transportation (ICT) is an innovative partnership between the IllinoisDepartment of Transportation (IDOT) and the University of Illinois at Urbana-Champaign(UIUC).

characterizing traffic for rigid pavements in illinois

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