Equivalent Axle Loads - Memphis Slides/Lecture 5 Slides.pdf · FHWA Truck Classes 13 Seven or More Axle Multi-Trailer Trucks 1.39 12 Six-Axle Multi-Trailer Trucks 1.06 11 Five or

Equivalent Axle Loads

Mazda Miata

( )1 consumption per passage=MM

dN

Curb weight = 2300 lb

Ford Excursion

( )1 consumption per passage=FF

dN

Curb weight = 6300 lb

“Standard” Vehicle

( )1 consumption per passage=SS

dN

Curb weight = 4000 lb

Equivalent Vehicle Factors

= =F SF

S F

Ford Excursiond NFd N

= =M SM

S M

Mazda Miatad NFd N

Standard Axle Load

Single Axle, Dual Wheels

Source: WSDOT Pavement Guide Interactive CD-ROM

9 kips

9 kips

FHWA Class 4

Source: WSDOT Pavement Guide Interactive CD-ROM

FHWA Class 5

Source: WSDOT Pavement Guide Interactive CD-ROM

FHWA Class 6

FHWA Class 7

FHWA Class 8

Source: WSDOT Pavement Guide Interactive CD-ROM

FHWA Class 9

Source: images.encarta.msn.com

FHWA Class 10

Source: WSDOT Pavement Guide Interactive CD-ROM

FHWA Truck Classes

1.39Seven or More Axle Multi-Trailer Trucks131.06Six-Axle Multi-Trailer Trucks 120.82Five or Less Axle Multi-Trailer Trucks110.93Six or More Axle Single Trailer Trucks101.20Five-Axle Single Trailer Trucks90.30Four or Less Axle Single Trailer Trucks80.42Four or More Axle Single Unit Trucks70.42Three-Axle Single Unit Trucks60.26Two-Axle, Six-Tire, Single Unit Trucks50.57Buses4negligibleOther Two-Axle, Four-Tire Single Unit Vehicles3negligiblePassenger Cars2negligibleMotorcycles1EALFTypeClass

TDOT Simplified System

1.7801.1009 -115-axle or more Combos

0.7800.70084-axle Combos

1.0000.7006, 73-axle or more Singles

0.1700.17052-axle, 6-tire Singles

0.3000.3004Buses

0.0050.0043Pickups, Panel Vans

0.0010.0011, 2Cars & Motorcycles

RigidEALF

FlexibleEALF

FHWAClass

VehicleType

WSDOT Simplified System

Daily ESALs = 0.40(single units) + 1.00(double units) + 1.75(trains)

1.7511, 12, 13Trains

1.008, 9, 10Double Units

0.404, 5, 6, 7Single Units

Assumed EALFFHWA ClassesWSDOT Category

Source: WSDOT Pavement Guide Interactive CD-ROM

Weigh Stations

Axle Load Histogram

0

100

200

300

400

500

600

3000-6999 7000-7999 8000-11999

12000-15999

16000-17999

18000-19999

20000-21999

22000-23999

24000-25999

26000-29999

Single Axle Load (lbs)

Freq

uenc

y

Axle Load Histogram

0

50

100

150

200

250

6000-11999

12000-17999

18000-23999

24000-29999

30000-31999

32000-33999

34000-35999

36000-37999

38000-39999

40000-41999

Tandem Axle Load (lbs)

Freq

uenc

y

Single Axles

5.395.39126000-29999

229.2TOTAL =

3.533.53124000-25999

5.162.58222000-23999

9.151.83520000-21999

40.91.243318000-19999

59.70.7967516000-17999

55.44.36015412000-15999

43.38.0884938000-11999

3.78.0271407000-7999

2.79.0055573000-6999ESALsEALF

Axle Countper 1000 trucks

Load Group(lbs)

Tandem Axles

2.32.29140000-41999

169.0TOTAL =

1.91.89138000-39999

4.61.54336000-37999

7.41.23634000-35999

24.30.972532000-33999

43.90.7575830000-31999

60.10.42914024000-29999

16.20.15010818000-23999

6.00.03716212000-17999

2.30.0102276000-11999ESALsEALF

Axle Countper 1000 trucks

Load Group(kips)

Average Truck Factor

229 169 0.401000+= = =ESALsTF

Vehicles

Pavement Life (Fatigue)

2 31

− −= εa af tN a E

Equivalent Axle Load Factor

21

−

= =a

si

i

a ENEALFN

( ) 3

21

−

−

εas

t

aa E ( )3

3−

ε⎛ ⎞= ⎜ ⎟ε⎝ ⎠ε

ait

a sitt

3 ≤ a3 ≤ 6

Pavement Life (Rutting)

54

−= ε af cN a

Equivalent Axle Load Factor

4= =si

i

aNEALFN

( ) 5

4

−ε

asc

a ( )5

5−

ε⎛ ⎞= ⎜ ⎟ε⎝ ⎠ε

aic

a sicc

3.5 ≤ a5 ≤ 4.5

Pavement Life (Rigid)

4

225,000 σ⎛ ⎞= ⎜ ⎟⎝ ⎠

tfN

MOR

Equivalent Axle Load Factor

σ= =

sts

ii

MORNEALFN

( ) 4−

σit MOR( )

4

4−σ⎛ ⎞= ⎜ ⎟σ⎝ ⎠

itst

Generic Axle Load Factor

4 4 4σ ε⎛ ⎞ ⎛ ⎞ ⎛ ⎞≈ ≈ ≈⎜ ⎟ ⎜ ⎟ ⎜ ⎟σ ε⎝ ⎠ ⎝ ⎠ ⎝ ⎠

i i ii

S S s

WEALFW