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 7306ENG-Transportation Infrastructure 1
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
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
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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
7306ENG-Transportation Infrastructure 3
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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
7306ENG-Transportation Infrastructure 4
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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
7306ENG-Transportation Infrastructure 5
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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.
7306ENG-Transportation Infrastructure 6
Table 2.2: Side Friction FactorTable 2.1: Superelevation
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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.
7306ENG-Transportation Infrastructure 7
Table 2.3. Summary of Radius of Curvature
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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.
7306ENG-Transportation Infrastructure 8
Table 2.4. Summary of Stopping Sight Distance (SSD)
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
7306ENG-Transportation Infrastructure 9
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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)
7306ENG-Transportation Infrastructure 10
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
Chainage SP = Chainage TC + L2
SP = 158.20 + 188.68
2 = 252.54 m.
(Written as, 0 + 252.54 with numbers before + sign represents kilometers)
Chainage CT = Chainage TC + L
CT = 158.20 + 188.68 = 346.88 m.
(Written as, 0 + 346.88 with numbers before + sign represents kilometers)
Chainage of Next IP = Chainage CT – Tangent + Next Leg
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
= 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
7306ENG-Transportation Infrastructure 18
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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
7306ENG-Transportation Infrastructure 19
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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.
7306ENG-Transportation Infrastructure 20
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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.
7306ENG-Transportation Infrastructure 21
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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,
7306ENG-Transportation Infrastructure 22
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
***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)
7306ENG-Transportation Infrastructure 23
CBR 5 Subgrade
CBR 5 Subgrade
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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
7306ENG-Transportation Infrastructure 24
350 mm Granular base
180 mm Asphalt
180 mm Asphalt
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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.
4. 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:
7306ENG-Transportation Infrastructure 25
με = 428.33from CIRCLY (Figure 3.1 )Result: N=2.27 x109
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
9. Determination of fatigue criteria for asphalt:
Volume of Bitumen, Vb = 11%
RF = 1.5, (Table 6.14, Austroads 2010)
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
Both should be checked directly beneath one of the loaded wheels.
13. CIRCLY output
7306ENG-Transportation Infrastructure 33
In SummaryDESA = 4.131 x106
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
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
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.
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!
7306ENG-Transportation Infrastructure 34
Figure 3.3. Full Depth Asphalt (CIRCLY 5.0 result)
Table 3.3 Full Depth Asphalt
CBR 5 Subgrade
PROJECT REPORT: ROAD AND PAVEMENT DESIGN [s2726109-MPN2011]
3.3.4. Asphalt, Granular Base and Cemented Sub-base
1. Trial Pavement
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. 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