design traffic

1Babak Shahbodagh KhanCE 507, School of Civil & Environmental [email protected]

CVEN3031: CIVIL ENGINEERING PRACTICE

CVEN3731: ENVIRONMENTAL ENGINEERING PRACTICE

Semester 2, 2014

PROJECT 2

Design Traffic

Content

2

Introduction

Traffic Parameters

Examples

2Fork lift zone

New Container Terminal

Fork lift & Truck zone

Straddle carrier zone

Rigid pavement zoneFlexible pavement zone

Container rows (3315 m)

Reclaimed soil zoneExisting natural soil zone

New realigned road

300 mProject 2

1. Subgrade Evaluation

2. Design Traffic

3. Design Flexible

Pavement

4. Design Concrete Pavement

4

Main Reference

Austroads Pavement Design Guide

https://www.onlinepublications.austroads.com.au/items/AGPT02-12

35

Design Traffic

Austroads Pavement Design Guide(Chapter 7)

6

Introduction

Figure 8.4 Design chart for granular pavements with thin bituminous surfacing

AUSTROADS Pavement Design Guide

47

Introduction

Design Traffic:

Convert loads of various magnitudes and repetitions (mixed traffic) to an equivalent number of standard loads.

Design Traffic is the function of number and types of vehicle loads that a particular pavement will be subject to, over its design life.

1) Vehicles Loads Different

2) Load Repetitions Pavement Design Life

Vehicles

Load distribution

TypesLoads

Survey data

Equivalent Standard Load

8

Design Traffic:

1) Vehicles Loads DifferentVehicles

Load distributionEquivalent Standard Load

TypesLoads

The damage caused to a pavement by the passage of one heavy vehicle depends on The number of axles on the vehicle; The manner in which these axles are grouped together into axle groups The loading applied to the pavement through each of these axle groups.

Traffic Parameters

59

Traffic Parameters

- Wide range of loads- Strong enough to cater the heaviest vehicle



TypesLoads

Pavement Pavement applications

10AUSTROADS

Pavement Design Guide

Types of Vehicles for Road Pavements:

light vehicles Contribute very little to structural deterioration

Traffic Parameters



TypesLoads

611

AUSTROADS Pavement Design

GuideClasses 3-12: Heavy vehicles

Traffic Parameters

Types of Vehicles for Road Pavements:

Only heavy vehicles are considered in pavement design.

12

Traffic Parameters

The axle configuration



TypesLoads

The damage caused to a pavement by the passage of a heavy vehicle depends on the number of axles on the vehicle; the manner in which these axles are grouped together into axle groups The loading applied to the pavement through each of these axle groups.

Axle group: A set of closely spaced axles acting as a unit (adjacent axles are less than 2.1 m apart)

713

Single Axle Single Tyre - SAST Single Axle Dual Tyre - SADT

Tandem Axle Single Tyre - TAST Tandem Axle Dual Tyre - TADT

Traffic Parameters

Tri-Axle Dual Tyre - TRDT

Quad-Axle Dual Tyre - TRDT

Traffic Parameters

14

82

32

2

3 3

15

Numbers of heavy vehicle axle groups per heavy vehicle (NHVAG):

Traffic Parameters

3 4

5 7

Traffic Parameters

16

Numbers of heavy vehicle axle groups per heavy vehicle (NHVAG):

917

Design Traffic:



TypesLoads

The damage caused to a pavement by the passage of a heavy vehicle depends on The number of axles on the vehicle; The manner in which these axles are grouped together into axle groups The loading applied to the pavement through each of these axle groups.

Traffic Parameters

Austroads Philosophy: Convert the number of repetitions of each Heavy Vehicle Axle Group into the number of Standard Axle repetitions that cause the equivalent amount of damage.

8.2t

Single Axle Dual Tyre - SADT

Standard Axle & Standard Axle Load

SADT carrying a load of 80 kN, with a width between the dual tyres of 1800 mm.

Traffic Parameters

Austroads Philosophy: Convert the number of repetitions of each Heavy Vehicle Axle Group into the number of Standard Axle repetitions that cause the equivalent amount of damage.

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10

Standard Axle & Standard Axle Load

Traffic Parameters

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Circular (radius = 92.1 mm)Load on tyre = 80 kN / 4 = 20 kN

Tyre-pavement contact stress = 750 kPa

Contact surface:

Tyre-pavement contact stress assumed to be uniform and equal to tyre pressure - 750kPa

SADT carrying a load of 80 kN, with a width between the dual tyres of 1800 mm.

Loads on axle groups that cause the same amount of damage (deflection) as the standard axle:

20

90kN 135kN

181kN

53kN

Single axle with single tyres (SAST)

80kN

Single axle with dual tyres (SADT)

Tandem axle with single tyres (TAST)

Tandem axle with dual tyres (TADT)

Tri-axle with dual tyres (TRDT):

Traffic Parameters

Above loads are all equal to 1 standard axle

Standard Axle

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21

Example 1

53kN 135kN 135kN181kN 181kN

Double road train (Class 11)

For one pass of the vehicle shown above, calculate:

1) Numbers of heavy vehicle axle groups (NHVAG):

2) Equivalent standard axles (ESA):

(per heavy vehicle)

1 ESA 1 ESA 1 ESA 1 ESA 1 ESA

5

5 ESA

22

Example 2

Double road train (Class 11)

For one pass of the vehicle shown above, calculate:

1) Numbers of heavy vehicle axle groups (NHVAG):

2) Equivalent standard axles (ESA):

(per heavy vehicle)

55kN 150kN 150kN190kN 190kN

5

???

12

23

Standard Axle Repetitions

Traffic Parameters

Standard axle repetitions are dependent on pavement type and damage exponent m

24

Traffic Parameters

13

55kN 150kN 150kN190kN 190kN

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Example 2

53kN 135kN 135kN181kN 181kN(Standard)

Granular base

Subgrade

Granular pavement with thin bituminous surfacing

4 4 4 4 455 150 190 150 190ESA= 6.6253 135 181 135 181

Once above truck traversing the granular pavement

Equivalent to 6.62standard axle

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Traffic Parameters

14

Designation Standard Load (kN)

Standard Load

(tonnes)

Legal Limit (tonnes)

SAST 53 5.4 6.0

SADT 80 8.2 11.0

TAST 90 9.2 10.0

TADT 135 13.8 17.0

TRDT 181 18.5 21.5

QADT 221 22.5 27.0

Traffic Parameters

- Legal Load Limit

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28

Design Traffic:

Damage Index

Traffic Parameters

1) Vehicles Loads Different

2) Load Repetitions Pavement Design Life

Vehicles


Number of heavy vehicle axle groups (HVAG) passing the design lane during design period (NDT)

15

29

Traffic ParametersLoad Repetitions

(Annual Average Daily Traffic)

NDT

30

Design Period (P)

Time span considered for the road pavement to function without major rehabilitation or reconstruction.

It is not the period until the next resurfacing!!

The considerations in selecting the design period:

Available funds The importance of the road


Traffic Parameters

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31

Annual Average Daily Traffic (AADT)

Average daily number of (Light + Heavy) vehicles in the 1st year of service.

Obtained from the actual traffic survey on the existing roadway where the pavement is to be constructed, or on nearby roads with similar travel patterns.

The traffic survey data should be Recent Obtained without interruption of the traffic stream.

Traffic Parameters

32

Annual Average Daily Traffic (AADT)

"A WIM, Weigh-In-Motion" system is a type ofvehicle detection system(VDS) that can measurethe traffic parameters such as the moving carsweight, speed, and type.

Traffic Parameters

17

33

Heavy Vehicle Factor (%HV)

Only heavy vehicles are considered in pavement design.

Heavy Vehicle factor %HV, which is the average percentage of all traffic comprising heavy vehicles, can be determined based on the traffic survey.

Average daily number of Heavy vehicles in the 1st year of service.

AADT %HV/100

Traffic Parameters

Traffic Loads

34

Directional Distribution Factor (DF)

Annual average daily traffic (AADT) is historically for traffic in both directions of a road. The directional distribution factor (DF) is multiplied with the AADT (usually = 0.5) to obtain

the daily traffic in one direction.

18

Traffic Loads

35

Lane Distribution Factor (LDF)

Location Lanes Each Direction


Left Lane Centre Lane Right Lane

Rural2 lane 1.00 N/A 0.50

3 lane 0.95 0.65 0.30

Urban2 lane 1.00 N/A 0.50

3 lane 0.65 0.65 0.50

Lane Distribution Factor (LDF): Proportion of traffic assigned to a specific lane. It is obtained from traffic survey data. The same pavement configuration is usually adopted for all lanes. It is determined for the WORST CASE (The most heavily-trafficked lane).

Outside lane

Traffic Loads

36

Cumulative Growth Factor (CGF)

During the design period, the daily volume of traffic is likely to change. The growth is estimated base on growths experienced by similar roads in vicinity R% : Annual Growth Rate

P2 P-1 (1 0.01R) 11 (1 0.01R) (1 0.01R) ... (1 0.01R) for R 0CGF 0

esign Period:Year.01R

P (D for R 0s)


19

Traffic Loads

37

Axle Groups per Heavy Vechicle (NHVAG)

Axle Groups per Heavy Vehicle:

In the absence of survey data, a presumptive value need to be selected.

NHVAG

Rural Areas 2.8

Urban Areas 2.5

HVAGNumber ofN

Number of axel groups

heavy vehicles

Traffic Loads

38

Cumulative Heavy Vehicle Axle Groups (NDT)

Number of heavy vehicle axle groups (HVAG) passing the design lane during design period

NDT = 365 AADT DF %HV/100 LDF CGF NHVAG

AADT = Annual Average Daily Traffic in vehicles per day in the first year

DF = Directional distribution factor

%HV = average percentage of all traffic comprising Heavy Vehicles

NHVAG = average Number of Axle Groups per Heavy Vehicle

LDF = Lane Distribution FactorCGF = Cumulative Growth Factor

20

Assume: Rural road Annual Average Daily Traffic (AADT) = 20,000 %HV = 12% Annual growth = 3% No. lanes = 4 (2 in each direction) Design period = 30 years

Determine design traffic for : a) Thin asphalt on unbound granular b) Structural (thick) asphalt on cemented base.

Note: No details of heavy vehicle types known

Example 1

39

Step 1. Calculate Cumulative Growth Factor CGF

CGF = (1 + 0.01R)P 10.01R

where R = 3 = annual growth rate (%)P = 30 = design period (years)

CGF = (1 + 0.01x3)30 1 = 47.50.01x 3

Example 1

40

21

Step 2. Determine Direction Factor DF DF = 0.5 (2 way traffic)

Determine Lane Distribution Factor LDF LDF = 1 (select heaviest lane)

Example 1

41

Location Lanes Each Direction


Left Lane Centre Lane Right Lane

Rural2 lane 1.00 N/A 0.50

3 lane 0.95 0.65 0.30

Urban2 lane 1.00 N/A 0.50

3 lane 0.65 0.65 0.50

Step 3.

Determine NHVAG = 2.8

Step 4. Calculate Design Traffic NDT

NDT = 365 (AADT DF) %HV/100 NHVAG LDF CGF

= 365 (20,000x0.5) 12/100 2.5 1.0 47.5

= 5.8 107 HVAG

Example 1

NHVAGRural Areas 2.8

Urban Areas 2.5

42

22

Step 5. Determine ESA/HVAG Calculate Design Traffic DESA

DESA = ESA/HVAG NDT (Austroads 7.4)= 0.9 ESA/HVAG 5.8 107 HVAG= 5.24 107 ESA

(This is the design traffic for a granular pavement with thin surfacing)

Example 1

43

= 0.9

Step 6. For alternative stabilised pavement with structural asphalt surface: Calculate Design Traffic DSARm

DSARm = SARm/ESA DESA (Austroads 7.5)

DSAR5 = 1.1 5.24 107 ESA = 5.77 107

DSAR7 = 1.6 5.24 107 ESA = 8.39 107

DSAR12 = 12 5.24 107 ESA = 6.29 108

Example 1

44

23

Design Traffic Using WIM Data

45

Steps: Determine numbers of each vehicle type Determine total numbers of each axle group Apply distribution of loads on axle groups Calculate equivalent damage factor for each load increment for each axle type SARijm

Basic equation:DSARm= NDT x Pi x Pij x (Lij/SLi)m

DSARm = design no. Standard Axle RepititionsNDT = Total no axle groups on design lanePi = Proportion axle groups type iPij = Proportion all type i axle groups with loads ijLij = jth load magnitude carried on type i axleSLi = standard axle loading for type i axle m = damage exponent for damage type m

If the designer has access to project-specific WIM data, the relevant design traffic values are then determined as follows:

Example 2

46

Calculation of ESAs and DSARm by Average Daily Axle Types

Class 3300 units

Class 4 120 units

Class 5 60 units

Class 890 units

Class 960 units

Class 1020 units

24

Example 2

47

Calculate number of each axle type (per day):

Truck Class

Number Units

Axle Load GroupSAST SADT TAST TADT TRDT

3 300 300 3004 120 120 1205 60 60 608 90 90 1809 60 60 60 60

10 20 20 40 20

Example 2

48

Assuming:- Design period 20 years, - Growth 4 %, - 2 lane dual carriageway, - Single direction count.

CGF = 29.8 LDF = 1.0

Calculate number of each axle type (for the whole design life)

Truck ClassNumber

UnitsAxle Load Group

SAST SADT TAST TADT TRDT3 3260700 3260700 32607004 1304280 1304280 13042805 652140 652140 6521408 978210 978210 19564209 652140 652140 652140 652140

10 217380 217380 434760 217380

25

Example 2Axle Group

LoadAxle Group Type

SAST SADT TAST TADT TRDT(kN) % % % % %10 0.2804 3.4730 0.0354 0.1444 0.005020 7.8270 8.6960 0.2377 0.5755 0.156830 15.4600 23.4600 0.2763 0.6242 0.329040 15.7100 21.9300 0.5755 1.9770 1.317050 29.9400 16.8000 2.8890 6.4960 4.167060 23.2900 9.6060 10.2700 9.5110 7.419070 6.5020 6.5000 16.8100 10.9400 9.777080 0.7943 4.6230 16.6100 9.7690 8.338090 0.1087 2.9690 15.9500 7.6110 6.1500100 0.0354 1.3930 14.4200 7.2420 5.0290110 0.0174 0.4098 9.7740 6.2670 3.7010120 0.0174 0.1158 5.9030 5.9520 3.2980130 0.0174 0.0244 2.9430 5.8780 3.1470140 1.5390 6.5340 3.3610150 0.8439 8.0300 4.0080160 0.4279 5.7170 4.1150170 0.2308 3.5540 4.8190180 0.1367 1.8630 6.0970190 0.0723 0.8535 7.7330200 0.0555 0.3331 8.4330210 0.0801 5.1360220 0.0322 2.3390230 0.0160 0.7764240 0.2503250 0.0905260 0.0080

TOTAL 100.0 100.0 100.0 100.0 100.0

E.g. 6.5% of all single axle dual tyre loads carry

approx 70kN

Presumptive Traffic Load Distribution for urban road

Example 2

(6.5% of 300 single axle dual tyre loads in 70kN) GF 365

= 6.5/100 300 29.78 365 = 211,945

- Multiply Number of axles of each type by load proportion

Axle Group Load

No Axles in Load GroupSAST SADT TAST TADT TRDT

(kN) [NAj] [NBj] [NCj] [NDj] [NEj]10 17981 113244 231 7220 4320 501923 283550 1550 28774 136330 991405 764960 1802 31208 286140 1007437 715071 3753 98845 1145250 1919965 547798 18840 324783 3623360 1493520 313223 66975 475525 6451070 416954 211945 109625 546971 8501380 50936 150742 108320 488425 7250190 6971 96810 104016 380530 53475100 2270 45422 94039 362081 43728110 1116 13362 63740 313334 32181120 1116 3776 38496 297584 28677130 1116 796 19192 293885 27364140 0 0 10036 326683 29225150 0 0 5503 401479 34850160 0 0 2791 285835 35781170 0 0 1505 177691 41902180 0 0 891 93145 53015190 0 0 471 42673 67240200 0 0 362 16654 73327210 0 0 0 4005 44659220 0 0 0 1610 20338230 0 0 0 800 6751240 0 0 0 0 2176250 0 0 0 0 787260 0 0 0 0 70

TOTAL 6412709 3260700 652140 4999739 869520

HVAG's = 1.62E+07

NHVAG 2.3

26

Example 2

51

Damage Exponents:

Design Method

Pavement Type Damage Type Damage unit Damage exponent (m)

Emperical granular with thin bituminous surfacing

Overall pavement damage

ESA 4

Mechanistic Pavement contains one or more bound

layers

Fatigue of asphalt

SAR5 5

Rutting & shape loss

SAR7 7

Fatigue of cemented

layers

SAR12 12

Example 2Axle Group

LoadDesign ESA for overall pavement damage

SAST SADT TAST TADT TRDT

(kN) [NAj(L/53)4] [NBj(L/80)4] [NCj(L/90)4] [NDj(L/135)4] [NEj(L/181)4]10 23 28 0 0 020 10178 1108 4 14 030 101773 15127 22 76 240 326854 44692 146 762 2750 1520792 83587 1795 6111 21160 2453085 99106 13230 18554 77970 1268753 124239 40117 39539 190280 264413 150742 67624 60231 276790 57961 155071 104016 75166 3269100 28770 110892 143330 109011 4074110 20704 47763 142237 138116 4390120 29323 19115 121666 185781 5540130 40389 5548 83548 252706 7282140 0 0 58765 377836 10460150 0 0 42465 611918 16438160 0 0 27874 563976 21848170 0 0 19160 446813 32608180 0 0 14264 294385 51853190 0 0 9365 167429 81645200 0 0 8826 80224 109312210 0 0 0 23449 80922220 0 0 0 11354 44390230 0 0 0 6740 17602240 0 0 0 0 6728250 0 0 0 0 2864260 0 0 0 0 296

TOTAL 6123019 857018 898454 3470190 507209DESA = 1.19E+07

ESA/HVAG = 0.73

211,945 axles (Lij/Pij)mLij = 70kN (load bin)Pij = 80kN (for SADT)m = 4 (for overall pavement damage)DESA = 211,945 (70/80)4

= 124,239

- Multiply no. axles (load/standard load)m

27

Example 2

211,945 axles (Lij/Pij)mLij = 70kN (load bin)Pij = 80kN (for SADT)m = 5 (for asphalt fatigue)

DESA = 211,945 (70/80)5= 108,709


Axle Group Load

Design Std Axles Repetitions for Asphalt Distress SAST SADT TAST TADT TRDT


TOTAL 6955885 830755 1137065 3835105 530951

DSAR5 = 1.33E+07

Example 2

211,945 axles (Lij/Pij)mLij = 70kN (load bin)Pij = 80kN (for SADT)m = 12 (for cemented fatigue)

DESA = 211,945 (70/80)12= 42,689


Axle Group Load

Design Std Axles Repetitions for Cemented Layer Distress SAST SADT TAST TADT TRDT


TOTAL 115406330 2634235 27000517 16474380 1151075

DSAR12 = 1.36E+08

28

Example 2

211,945 axles (Lij/Pij)mLij = 70kN (load bin)Pij = 80kN (for SADT)m = 7 (for deformation)

DESA = 211,945 (70/80)7= 83,230


Axle Group Load

Design Std Axles Repetitions for DeformationSAST SADT TAST TADT TRDT


TOTAL 10426466 952458 2173731 5205478 622307DSAR7 = 1.72E+07

Project 2

Input Traffic Data

- Existing traffic on the access road:

- Road Traffic Counts- Presumptive Traffic Load Distribution (Urban Area)

- Additional traffic generated by the port development:

- Container Load Distribution- Types of Trucks used to transport Containers

Existing traffic + Additional traffic DSARm

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design traffic

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