Rural Road Design(AUSTROADS2009)

PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]

CHAPTER 1: INTRODUCTION

A development of a low volume rural road requires an appropriate design construction

and a long term management. Rural infrastructure development in this case should have a direct

impact on their design if they are to be part of a sustainable infrastructure. Basically, road

infrastructures are developed to generate significant reductions in poverty. Reducing transport

accessibility to households will definitely result to pro-poor. By improving the quality of rural

roads, this will also result in parallel to improve access to education, health centers, markets to

buy and sell, employment, family, and other activities on the nearby cities.

The present paper will analyze step by step the process of designing a road and pavement

of a particular two-lane two-way rural road connecting two points, following the Australian

standards given by Austroads.

This first chapter will present the prior assumptions and objectives in designing the

geometric elements of the two-lane two-way rural road connecting points O to D as shown in

Figure 1.1.

1.1. Overview

The development of a new road infrastructure located in Mount Nathan has been

proposed as shown in Figure 1.1. The proposed road infrastructure design are required to

meet the standard requirements in relevant to considering safety, amenity, convenience,

economy and sustainability. The design geometry of the road also should satisfy in terms of

its route location, horizontal and vertical alignments, cross-sectional elements and

earthworks.

7306ENG-Transportation Infrastructure 1


Figure 1.1 Proposed developments detailing geographical location

1.2. Design Assumptions and Constraints

Design period= 20 years

Present year AADT = 4000 vehicles/day

Percentage of heavy vehicles = 10%

Compound growth factor =1.2%

Sub-grade CBR = 5%

Design speed= 80km/hr

K-factor = 15%

Directional distribution: 50/50

Maximum grade = 7% (rolling terrain)

Maximum height of the fill: 2.5m

Maximum height of cut: 3.0m

The following design was analyzed using 12d Model 9 road design software. The terrain

and contours were given in an electronic topographic map (Figure 2.2), as well as, the starting

point O (5263340.648, 6904871.943, 80) and end point D (525962.510, 6906996.263, 38).



CHAPTER 2: ROAD DESIGN

2.1. Overview

This second chapter will present the process of designing the geometric elements of the

two-lane two-way rural road connecting points O to D (see Figure 2.1). This involves evaluation

of route location, traverse layout (tangents and curves), horizontal alignment (curves,

superelevation, sight distances), vertical alignment (grades, curves, sight distances), Cross-

sectional elements (lanes, shoulders, drains) at 50m interval, earthworks and mass-haul diagram

using 12d Model 9 Software in junction with elementary analysis on cut and fill volume

calculations.

2.2. Design Input Parameters

2.2.1. Roadway Location

The road is located in a rural area of low traffic volume connecting an existing

road to a specified point which is presently, with no access or roadway provided. (See

Figure 1.1)

2.2.2. Topography and/ or Geological Features

The following design was analyzed using 12d Model 9 road design software. The

terrain and contours were given in an electronic topographic map (Figure 2.2), as well as,

the starting point O (5263340.648, 6904871.943, 80) and end point D (525962.510,

6906996.263, 38).

Figure 2.1. Electronic topographic map



The geometric road design was started by inputting the topographic data into 12d

Model 9 software to create the assistance of the complicated terrain, as shown in Figure

2.2.

Figure 2.2. OD Data Output

Next step is the triangulation of the data source and it is intentionally performed in order to obtain a better perspective view of the topography.

Figure 2.3. 3D Output



After this step is completed, contours could be generated by the software, showing the terrain elevation in meters. The starting point O, is located on an elevation of 82.56 meters while the end point D of the road is situated at 39.65 meters above the sea level.

Figure 2.4. Tin Ground with Road Center Line

2.2.3. Traffic and Human Factors

The road is designed for local traffic with a given K value of 15% as defined by

the project requirement. Using the provided data, AADT = 400 vehicle per day and the

comparison of the two categories of two-lane two way road (Nepal 2011), it proposed

road falls to Class II two- lane two way road. Basically, the road is located between major

urban centers through a mountainous terrain.

The driver’s eye height for a car is provided to be 1.1 meters and the object height

on a road is 0.2 meters ( Austroads 2009). It is also noted that the driver’s perception

reaction time varies from 1 to 3.6 seconds and in this design analysis, reaction time of 2.5

seconds be used as a desirable value.

2.2.4. Speed Parameters

Road traffic is a complex system in which several components interact

simultaneously. For a sustainable transportation system, it has to cater safety, convenient,

comfortable, secured, continuous, system coherency and attractive road design. But of all,

the most important requirement for a new road design is the selection of the appropriate



operating speed. This design speed was a analyzed in a iterative approach, which is

directly influenced by road design parameters including sight distance, horizontal curve

radii and topography. Standard parameters and sample computation as provided below

shows how reliable the analysis is.

R= v2

¿¿

where:

e max = superelevation, refer to Table 2.1

f max = side friction factor, refer to Table 2.2

v =speed, m/s2

g = acceleration due to gravity (9.81 m/s2)

R = radius of curvature, m.

Sample calculation:

R= v2

¿¿

R = ( 703.6

)2

(0.07+0.19 )9.81

R = 148.23 m. ≈ 150 m.


Table 2.2: Side Friction FactorTable 2.1: Superelevation


Summary

2.2.5. Sight Distance Parameters

The stopping sight distance (SSD) was analyzed accordingly to the standard

parameters and road geometry. Standard parameters and sample computation as provided

below shows how reliable the analysis is.

where:

tr = perception reaction time, (Table 5.2, Austroads 2009)

v =speed of the vehicle, m/s2

g = acceleration due to gravity (9.81 m/s2)

G = longitudinal grade (percent)

d =coefficient of deceleration, (Table 5.3, Austroads 2009)

Sample computation:

SSD = v tr + v2

2 g(d± 0.01 G)

= 803.6 (2.5) +

( 803.6

)2

2∗9.81(0.46 ± 0.01∗7)

SSD = (+ G) 103.045 m., (- G) 120.09 m.


Table 2.3. Summary of Radius of Curvature


Summary:

2.3. Design of Horizontal Alignment

2.3.1. Overview

Horizontal alignments establish the general character of a rural road. The

configuration chosen for lines and grades affects safe operating speeds, sight distances,

and opportunities for passing and road capacity. Moreover, the decisions obtained on

alignment have a significant impact on construction time and costs. Accident rates are

also lowered if a good aesthetic road is provided, which will reduce driving tension and

weariness to the driver.

2.3.2. Tangents and Curves

Horizontal curves in the design of the horizontal alignment depends

directly to the speed and superelevations. A safe radius is defined as the minimum radius.

It is stated as safe since, values of superelevation (emax) and side friction (fmax) is taken

and this is a very conservative value in real world situation.

After series of iterations, the final geometry results to a total of nine

horizontal curves. The relevant horizontal alignment parameters are presented in

Appendix A, Table A.1 . The smallest radii used is 200 m. which satisfies the minimum

requirement of 92 m.


Table 2.4. Summary of Stopping Sight Distance (SSD)


Sample computation:

Length of Curve, L = π R ∆

180°

L = (3.1416) (200) (54 ⁰3 ’14.84 ”)

180 ° = 188.68 m.

Tangent of Curve, T = R tan ∆2

T = (200) tan (54 ⁰3 ’14.84 ”)

2 = 102.02 m.

Chainage TC = Previous leg – Tangent of Curve

TC = 260.22 – 102.20 = 158.20 m

(Written as, 0 + 158.20 with numbers before + sign represents kilometers)



Chainage SP = Chainage TC + L2

SP = 158.20 + 188.68

2 = 252.54 m.


Chainage CT = Chainage TC + L

CT = 158.20 + 188.68 = 346.88 m.


Chainage of Next IP = Chainage CT – Tangent + Next Leg

Next IP = 346.88 – 102.02 + 365.05 = 609.91

(Written as, 0 + 609.91with numbers before + sign represents kilometers)

External Distance, E = R ( secant ∆2

- 1)

E = (200) (secant 54 ⁰ 3’ 14.84 ”

2 – 1) = 24.52 m.

Middle Ordinate, M = R (1 – cosine ∆2

)

M = (200) (1- cosine 54 ⁰ 3’ 14.84 ”

2 ) = 21.84 m.

Length of Long Chord, C = 2 R sine ∆2

C = 2(200) sine 54 ⁰ 3’ 14.84 ”

2 =181.76 m.



Refer to appendix A. Table A.1 for full tabulation of the manual calculation of tangents and curves.


Table 2.5. Tabulated Results of Sample Manual Calculation

Summary of Formulas


2.3.3. Design Speed and Horizontal Sight Distance

All design speeds of the alignment chosen are in accordance with the

Austroads 2009. The design speed for each curve is detailed in Table 2.5.

2.3.4. Sight Distance, Comfort and Appearance Criteria

Minimum curve lengths are required to avoid kinks and maintain a satisfactory

appearance but these are also not an absolute minimum values. For a desirable

appearance of your road, Table 7.6, Austroads 2009 presents variance of speed with its

equivalent minimum horizontal curve lengths. For the comfort analysis, Lateral offset

limits are also presented in Figure 5.4, Austroads 2009.


Table 2.6 Design Speed and Horizontal Sight Distance

Table 2.7 Comfort and Appearance Criteria


2.4. Design of Vertical Alignment

2.4.1. Overview

Vertical elements should be superimposed on horizontal ones in such a way that

the intersection points practically coincide with the horizontal slightly in advance to the

vertical and horizontal and vertical curves of similar lengths. (Nepal 2011) The design

speed of the road in both planes are taken to be the same. In this case, it will give a hand

on the driver’s awareness of the speed environment.

2.4.2. Legs and Grades

Basically, as much as possible the grade of the road should follow the natural

contours, however, for the chosen road geometry, the minimum grade obtain is 0.192%.

On the other hand, the maximum grade of this alignment is 3.984%, which fall under 7%

absolute maximum grade or 5% desirable maximum grade and 0.3% absolute minimum

grade or 0.1% desirable minimum grade. (GCCC, 2005). Detailed plots are shown in

Appendix C.


Figure 2.5 Legs and Grades


2.4.3. Sight Distance, Comfort and Appearance Criteria

Sample computations:

Case of VIP 1.

RL of start point is provided as equal to 82.56m above sea level by 12D Model 9

Software.

Length of Curve computed computation is provided in Section 2.4.3.

RL (BVC) = RL of start point –{ g 1100

*(previous leg length - L2

)}

= 82.56 – {0.0386 *(241.683- 100)}

= 77.09 m (above sea level)

RL (PVI) = RL of start point –( g 1100

*previous leg length)

= 82.56 – (0.0386 *241.683)

= 73.23 m (above sea level)

RL (center of curve) = RL (PVI) + ymax



***note that + indicates that the curve is sag and point of the

center curve is above the projected leg line.

ymax = ((g2−g1 )∗0.01

2L) x2

x = L2

= Design Lengthof cur ve

2

x = 200

2 = 100 m.

ymax = ((2.6891 )∗0.01

2(200)) (100)2

ymax = 0.67225 m.

RL (center of curve) = RL (PVI) + ymax

= 73.23 m + 0.67225

RL (center of curve) = 73.90 m. (above sea level)

RL (EVC) = RL (PVI) –( g 2100

*L2

)

= 73.23 –( 1.171100

*100)

= 72.05 m. (above sea level)

The most critical vertical curve is PVI 2 which has a design length of 200 m. and

a minimum required length of 127.77 m. The most comfortable vertical curve is PVI 1

which has a design length of 200 m. and a minimum required length of 27.64 m. But in

general, the geometry parameters is way too far from the limit, meaning the design is too

conservative in terms of comfort. Refer to appendix B. Table B.1 for full tabulation of the

calculation

2.4.3. Minimum K values

The minimum size of vertical sag curves for different categories of roads using

both comfort criteria and headlight sight distance are listed in Figure 8.7, Austroads 2009.

On other case, crest vertical curves with its appearance criterion and sight distance

criterion is listed at table 8.6 and 8.7 of Austroads 2009, respectively. But in this report,



the design approach used is by adopting the empirical equations of K value as also

provided by Austroads 2009.

Sample computations:

VIP 1:

Type: Sag

SSD = SD = 103 m.

Using Austroads 2009 formulas for sag vertical curves:

Case 1:

= 1032

200¿¿ = 22.12

A = |g2 – g1| = 2.689

L = K A = (22.12)(2.689) = 59.48 m. ; L < SD, then it doesn’t satisfy!

Case 2:


Table 2.8 K- Values

L > SD

L < SD

SD = Sight Distanceh1 = observer’s height (1.1m)h2 = objects height (0.2m)h = mounting height of headlights (0.6m)V = speed (km/h)θ = elevation angle of beam (1º)g1 = grade previous legg1 = grade next legL =K AA = |g2 – g1|

K=( SD )2

200 (h+SD tanθ )

K= 2×SD|g2−g1|

−200 (h+SD tan θ)

(|g2−g1|)2

K=( SD )2

200 (h+SD tanθ )

K= 2×SD|g2−g1|

−200 (h+SD tan θ)

(|g2−g1|)2


= 2(103)2.689

– 200¿¿ = 10.28

L = K A = (10.98) (2.689) = 27.64 m.; L < SD, ok!

2.5. Design of Cross Sections

2.5.1. Overview

The dimension of a typical; cross section is based on parameters such as traffic

volume dimensions and combination of speed and traffic volume. (Austroads 2009)

2.5.2. Elements of Cross Sections

The whole length of the road design is considered to have a fixed cross section

lane width of 3.2 m, shoulder width of 1.2 m and the drainage details is taken as to be the

minimum design since, it is not included in the overall design analysis of the road design

project. The cross fall and superelevation slope of the road and shoulder varies

accordingly as chainage changes. This is due to the main purpose of the design which is,

to accommodate both cars and trucks for the design speed of the road.

2.5.3. Cross Section Plots

The required cross section plots at every 50 m chainage intervals are

provided in Appendix D.

Figure 2.6. Typical Fill Cross Sections



Figure 2.7. Typical Cut Cross Sections

2.6. Earthworks and Mass- Haul Diagram

2.6.1. Overview

Considering the terrain condition of Mount Nathan area, it is obvious that

it will undertake a large scale of excavation and earthwork activities. The final road

design was carefully evaluated to consider the cumulative cut and fill balance. At the

same time, the balance of the total haulage distance of the excavated mass is also

observed and considered due to the fact that these factors might affect to the economical

impact of the project. Excess cut was preferred also for the design. Practically, a

removal of volume of soil is cheaper and easier than importing additional fill materials.

2.6.2. Volume Calculations

In terms of volume calculation, there are a lot of mathematical formulas

that can be an option to be used on analyzing. But in this case, the total road length is

quiet long enough and contains series of numbers that may introduce to a bigger

possibility of committing errors in calculation. Using 12D Model 9.0 is the best approach



to calculate volume of earthworks. The software is design to have the same concept of

calculation which is the Average End Area Method. The summary of result is shown in

Table 2.9.

Table 2.9. Volume of Cut and Fill

Description Volume (m3)

Total Cut -23,361.387

Total Fill 23,292.601

Balance

(Excess Cut over Fill) -68.786

2.6.3. Mass- Haul Diagram

The final plotting of the graph indicates how much earth is needed (to fill) or in

excess (to cut) over the entire length of the project. If it indicates negative, it means

cutting, if it is positive, then it means filling. The rising of the curve indicates an

increasing volume of cut and the falling of the curve represents a decreasing volume due

to fill. The maximum point (-2980.159) in the negative quadrant represents the end of cut

and the maximum point (2824.478) in the positive quadrant represents the end of fill. At

the end of curve, it indicates that it is not equal to zero, that means it represents the waste

of soil materials.



0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

2600

2800

3000

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

-2980.159

2824.478

-68.7860000000001

Chainage

Bala

nce

Mas

s(C

utting

- Fi

lling

)

Figure 2.8. Mass Haul Diagram

The frequency of crossing along the zero axis shows that the amount of cut and

fill is evenly distributed along the road length. Also, the haul distance of cut and fill is

also average. The maximum haulage distance is no more than 100 m. in both either side

at chainage 1+500. The calculated final cut-fill balance of the road design was calculated

to be -68.786 m3, which is satisfying the maximum required of 10% of the total fill

volume.

The volume calculated represents an excess on cutting activity which in fact, there

is no need for the contractor to look for an imported fill. In this way, the desired

economical prospective is achieved.



CHAPTER 3: PAVEMENT DESIGN

3.1. Overview

Produce alternative flexible pavement designs for the same two-lane two-way rural road. The alternative design includes:

(a) Granular pavement with asphalt wearing surface(b) Asphalt surfaced pavement with cemented base(c) Full depth asphalt (d) Asphalt, granular base and cemented sub-base

3.2. Design Input Parameters

Design period = 20 yearsPresent year AADT = 4000 vehicles.Percentage of heavy vehicles= 10% vehicles. (Compound growth factor = 1.2%)Sub-grade CBR = 5%Design speed = 80km/hrK-factor = 15 %Directional distribution: 50/50Maximum grade = 7% (rolling terrain)Maximum height of the fill: 2.5mMaximum height of the cut: 3.0mTerrain and contours are shown in topographic map in Figure 1.2 and 2.1.Determination of lane distribution factor (LDF) = 1.0,



***refer to Appendix E.Table 7.3,Austroads,2010.Determination of cumulative growth factor (CGF) = 22.46

*** refer to Appendix E. Table 7.4., Austroads,2010NHVAG value can be obtain from Table F2, Austroads 2010, Presumptive traffic load distribution for rural road.Project Reliabilty = 90% , refer to Appendix E. Table 2.1

Cumulative HVAG = 365 x (AADT x DF) x HV x NHVAG x LDF x CGF = 365 x (4000 x 0.50) x 0.10 x 2.8 x 1.0 x 22.46

HVAG = 4.59 x 10 6

Establish the traffic load distribution (TLD):

Design SAR (DSAR):

Design ESA or DESA = ESA

HVAG x HVAG = 0.90 (4.59 x 106) = 4.131 x 106

DSAR5 = DESA x 1.1 = 4.5441 x 10 6

DSAR7 = DESA x 1.1 = 6.6096 x 10 6

DSAR12 = DESA x 1.1 = 4.957 x 10 6

3.3. Flexible Pavement Design

3.3.1. Granular Pavement with Asphalt Wearing Surface

Using Chart EC02:

The design approach of this type of Flexible Pavement Design was

carefully analyzed by using design charts, for a sub-grade Modulus of 50

MPa and DESA = 4.131 x 106 the appropriate chart is chart 2 (EC02).

(Austroads, 2010)


CBR 5 Subgrade

CBR 5 Subgrade


Thickness Superior Edge Selected Inferior Edge

Asphalt (mm) 205 180 170

Unbound Granular Material (mm)

100 350 500

Using CIRCLY 5.0 Software:

1. Trial Pavement


350 mm Granular base

180 mm Asphalt

180 mm Asphalt


2. Determination of elastic parameters for the in situ sub grade and selected

sub grade materials:

Computation:

Ev = 10 CBR = 50 MPa

Eh = E v2

= 25 MPa

v = vv= vh = 0.45 (unbound cohesionless)

f = Ev

1+v =

501.45

= 34.5

3. Condition is not relevant since none top granular sub-layer.


5. Not relevant.

6. Determination of elastic parameters for asphalt:

Ev= 2800 MPa v=0.40 (Assumed from urban design charts).

f = Ev

1+v =

20001.40

= 1,429

7. Adoption of sub grade strain criterion:

For pre-cracking:

8. Not relevant.

9. Determination of fatigue criteria for asphalt:


με = 428.33from CIRCLY (Figure 3.1 )Result: N=2.27 x109

In SummaryCBR = 5%Ev = 50 MPaEH = 25 MPaνv = νH = 0.45f = 34.5


N=[9300uε ]

7


Volume of Bitumen, Vb = 11%

RF = 1.5, (Table 6.14, Austroads 2010)

For pre-cracking:

10. Determination of design number of Standard Axle Repetitions (SAR) for each relevant distress mode:

From Previous Calculation:

11. Standard axle load represented as:

Tyre-pavement contact stress = 750 kPa

Load radius = 92.1 mm.

Four circular areas separated center-to-center 330 mm, 1470 mm

and 330 mm, refer to Appendix E. Standard axle location.

12. Critical locations to calculate strains are:

Top of sub-grade

Bottom of asphalt later

Bottom of cemented layer

13. CIRCLY output


με = 175.93 from CIRCLY (Figure 3.1 )Result: N=1.12x107

In SummaryDESA = 4.131 x106

DSAR5 = 4.5441 x106

DSAR7 = 6.6096 x106

DSAR12 = 4.957 x107

N=RF∗[6918 (0. 856×Vb+1 .08 )E0 .36×uε ]

5


14. Criterion comparison from step 7, 8 and 9. It is noted that the post-

cracking of the cemented material is not considered. The resulting

allowable loading is the same.

15. Checking of allowable loading versus the design traffic loading.

16. Remarks.

Since allowable loading of all layers is greater than design traffic

loading, the design is acceptable!


Figure 3.1. Granular Pavement with Asphalt Wearing Surface (CIRCLY 5.0 result)

Table 3.1 Granular Pavement with Asphalt Wearing Surface

170 mm Asphalt

240 mm Cemented base

CBR 5 Subgrade


3.3.2. Asphalt Surfaced Pavement with Cemented Base

1. Trial Pavement



Computation:


Eh = E v2

= 25 MPa


f = Ev

1+v =

501.45

= 34.5



5. Determine the elastic parameters for cemented materials (pre- cracking)

E = 2000 MPa

v = vv= vh = 0.2

***Note: That the thickness of the asphalt is less than the cemented

material or less than 175 mm. Therefore, there is no need for post-

cracking analysis. (Austroads,2010)



f = Ev

1+v =

20001.40

= 1,429





For pre-cracking:

8. Determination of fatigue criteria for cemented materials

Project Reliability = 90 %

RF = 2.0 (Table 6.8, Austroads 2010)




For pre-cracking:





DSAR5 = 4.5441 x106

DSAR7 = 6.6096 x106

DSAR12 = 4.957 x107

Result: N=4.28 x1011

με = 24.075 from CIRCLY (Figure 3.2 )

Result: N=6.43 x107


με = 247.31 from CIRCLY (Figure 3.2 )Result: N=81.06 x1011N=[9300

uε ]7

N=RF [ (113000E0. 804 )+191

uε ]12

N=RF∗[6918 (0. 856×Vb+1 .08 )E0 .36×uε ]

5





Four circular areas separated center-to-center 330 mm, 1470 mm

and 330 mm, refer to Appendix E. Standard axle location.


Top of sub-grade


Bottom of cemented layer

13. CIRCLY output



14. Criterion comparison from step 7, 8 and 9. It is noted that the post-

cracking of the cemented material is not considered. The resulting

allowable loading of all layers is the same.


16. Remarks.



3.3.3. Full Depth Asphalt


Figure 3.2. Asphalt pavement with cemented Base (CIRCLY 5.0 result)

Table 3.2 Asphalt pavement with cemented Base

200 mm Asphalt

CBR 5 Subgrade


1. Trial Pavement



Computation:


Eh = E v2

= 25 MPa


f = Ev

1+v =

501.45

= 34.5



5. Condition is not relevant since there are no cemented material.



f = Ev

1+v =

28001.40

= 2000


For pre-cracking:

8. Not relevant.


με = 563.25 from CIRCLY (Figure 3.4 )Result: N=3.34 x108


N=[9300uε ]

7










Four circular areas separated center-to-center 330 mm, 1470 mm and 330 mm, refer to Appendix E. Standard axle location.


Top of sub-grade


Both should be checked directly beneath one of the loaded wheels.

13. CIRCLY output



DSAR5 = 4.5441 x106

DSAR7 = 6.6096 x106

DSAR12 = 4.957 x107

Result: N=4.96 x106

με = 215.69 from CIRCLY (Figure 3.3 )N=RF∗[6918 (0. 856×Vb+1 .08 )

E0 .36×uε ]5


14. Criterion comparison from step 7, 8 and 9. Since there is no cemented layer

that is needed for any post cracking consideration, the resulting allowable

loading of the asphalt and sub-grade layer is the same.


16. Remarks.




Figure 3.3. Full Depth Asphalt (CIRCLY 5.0 result)

Table 3.3 Full Depth Asphalt

CBR 5 Subgrade


3.3.4. Asphalt, Granular Base and Cemented Sub-base

1. Trial Pavement



Computation:


Eh = E v2

= 25 MPa


f = Ev

1+v =

501.45

= 34.5

3. Evaluating the minimum elastic modulus:

E = 500 MPa

***for High Standard Crushed Rock (Table 6.3, Austroads 2010)

Ev = 500 MPa or Evsubgrade * 2(100/125) Ev = min( 500, 87.05) Ev = 87 MPaEh= 43.5 MPa v=0.35, f=Ev/1 + v = 87/(1+0.35) = 64.444Ratio of moduli of other sub-layers (R) = (87/50)1/5 = 1.117

4. Determine the elastic parameters and thickness of the other granular sub

layer:



195 mm Cemented sub-base


160 mm Asphalt


Five equal-thick sub-layers of

Material

Type

Thickness

(mm)

Elastic modulus

(MPa)Poisson’s ratios

f

EV EH VV VH

Granular 20 mm 87 43.5 0.35 0.35 64.4

Granular 20 mm 78 39 0.35 0.35 57.7

Granular 20 mm 70 35 0.35 0.35 51.8

Granular 20 mm 62 31 0.35 0.35 48.1

Granular 20 mm 56 28 0.35 0.35 41.4

Subgrade - 50 25 0.35 0.35 37.0

5. Determine the elastic parameters for cemented materials, pre fatigue

cracking:

For Pre-cracking:

Ev= 2000 MPa v=0.2 (From CIRCLY 5.0).

***Note: That the thickness of the asphalt is less than the cemented material or less than 175 mm. Therefore, there is no need for post-

cracking analysis. (Austroads,2010)


Ev= 3000 MPa v=0.40 (from CIRCLY 5.0)

f = Ev

1+v =

30001.40

= 2,142.86


For pre-cracking:

8. Determination of fatigue criteria for cemented material:



Result: N=4.20 x1010

με = 95.1from CIRCLY (Figure 3.4).RF = 2.0 (Using 90% project reliability)E = 2000 MPaResult: N= 2.0123 x103

N=[9300uε ]

7

N=RF [ (113000E0. 804 )+191

uε ]12










Four circular areas separated center-to-center 330 mm, 1470 mm and 330 mm, refer to Appendix E. Standard axle location.


Top of sub-grade


Both should be checked directly beneath one of the loaded wheels.

13. CIRCLY output


με = 188.07from CIRCLY (Figure 3.4 )

RF = 1.5 (Using 90% project reliability)

E = 3000 MPa

Result: N=4.96 x106


DSAR5 = 4.5441 x106

DSAR7 = 6.6096 x106

DSAR12 = 4.957 x107

N=RF∗[6918 (0. 856×Vb+1 .08 )E0 .36×uε ]

5

Table 3.4 Asphalt, Granular Base and Cemented Sub-base


14. Criterion comparison from step 7, 8 and 9. Since there is no cemented layer

that is needed for any post cracking consideration, the resulting allowable

loading of the asphalt and sub-grade layer is the same.


16. Remarks.



3.4. Rigid Pavement Design

3.4.1. Design Input Parameters

Type of pavement: Plain concrete pavement (PCP)

A concrete shoulder is provided

From Figure 9.1, Austroads 2010, 150 mm lean- mix concrete (LMC)


Figure 3.4. Asphalt, Granular Base and Cemented Sub-base (CIRCLY 5.0 Resul)

CBR 5 Subgrade


***The figure (Appendix E), shows that it is 125mm LMC, but

there is also a recommendation that 150 mm LMC is the

minimum thickness for jointed Undowelled bases.

Design CBR = 5%

Effective sub-grade design , Ef = 75% (Appendix E, Figure 9.1)

The characteristic 28- day flexural strength of the concrete is 4.5 MPa.

Desired Project Reliability is 90%, Appendix E (Table 2.1)

From Table 9.2, Austroads 2010, Load Safety Factor, Lsf = 1.20

Design Life = 20 yrs.

HVAG = 4.59 x 10 6 HVAG

Trial pavement is 186 mm ≈ 190 mm.

Undowelled PCP base pavement

Steps on Calculating of Expected Repetitions and Base Thickness Design

(Appendix E)

Step 1. Trial Base Thickness

Step 2. Calculation of Expected Repetitions

Single Axle/ Single Tyre (SAST)


186 mm ≈ 190 mm Plain Concrete Pavement150 mm LMC


Tandem Axle/ Single Tyre (TAST)

Single Axle/ Dual Tyres (SADT)



Tandem Axle/ Dual Tyres (TADT)

Triaxle/ Dual Tyres (TRDT)



Step 3. Rigid Pavement Base Thickness Design Calculation

Single Axle/ Single Tyre (SAST)

Tandem Axle/ Single Tyre (TAST)



Single Axle/ Dual Tyres (SADT)



Tandem Axle/ Dual Tyres (TADT)



Triaxle/ Dual Tyres (TRDT)

Since, fatigue and erosion percentage of damage is less than 100%, the design is acceptable!



CHAPTER 4: CONCLUSIONS AND RECCOMENDATIONS

A low volume rural road infrastructure needs serious design procedures in terms of its

geometric design and infrastructure sustainability. Main reason is, it is the main access of all

households and will introduce a definite development and improvement to the rural area.

A good road is not just compensating structural analysis but also, it should consider

safety, quality and performance. Generally, the geometric design of this report is normally within

the range of standard specifications. When in terms of sustainability, materials used in the

analysis have been proven for decades to be effective and reliable in terms of different distresses.

The final road design with length of 2.738 kilometers, 3.20 m width two lane- two way

road with a provided concrete shoulder is typically the most suitable design road in the selected

area. It is quite a long road but is intentionally design to introduce a safer environment. Since the

road is almost following to its smooth contour lines of the topography of the area, in terms of

vertical curves, drivers will not experience a very steep road. In terms of cost efficiency, the

chosen geometry provides a minimal gap of length of haulage, and minimal depth of cut and fill

in every road section. As presented in the Mass- Haul Diagram, the negative value of the excess

material represents a cutting activity. In this case, there is no need for the contractor to look for

another filling material. By which, obviously the scenario is advantageous in terms of costing.

Different alternatives were presented in the report but the choice of what would be the

final type of pavement is not decided, considering the fact that, all of the pavement type is

effective and can accommodate the required design traffic load. In actual practice, designers

should advice and recommend the final type of pavement.

. Moreover, it is very important to take note that, no matter how accurate the geometric

and pavement material analysis of the road, the realization of a zero accident road is way too

impossible to achieve. It is practically due to some factors caused by human, facilities or devices,

and other natural occurrences. In other words, the design of roads is just a tool to provide a safer

environment, but safety could be realized basically by its individual cautiousness.



REFERENCES

Austroads (2009). Guide to Road Design- Part 3: Geometric Design, Austroads Incorporated, Sydney, Australia.

Austroads (2010). Guide to Road Design- Part 3: Geometric Design, Austroads Incorporated, Sydney, Australia.

Main Roads ( 2002). Road Planning and Design Manual, Chapter 12- Vertical Alignment

Nepal, K.P (2011). 7306ENG- Transportation Infrastructure Lecture Notes- Griffith University- School of Engineering, Gold Coast, Australia


Table A.1. Horizontal Alignment Design Table


APPENDIX A



APPENDIX B


Table B.1. Vertical Alignment Design Table


APPENDIX C



APPENDIX D



APPENDIX E


Table 7.4: Cumulative Growth Factor (CGF) values for below-capacity traffic flow

Standard axle location.


Mechanistic Analysis: Input Requierements, Table 8.1 Austroads (2010)



Rigid Pavement Design Calculation


Rural Road Design(AUSTROADS2009)

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Transcript of Rural Road Design(AUSTROADS2009)