Assignment Task
Question 1
Calculate the cumulative design traffic for a flexible pavement structure using the details below:
Road type: Urban arterial
AADT (data year): 12,000 + the last 3 digits of your student ID
(So if my student ID is 0050056732 then the AADT will be 12,000 + 732 = 12,732)
HV% = 10%
Annual traffic growth rate = 4%
Annual heavy vehicle growth rate = 2%
ESA/HVAG = 0.75
NHVAG = 2.60
Design life = 20 years
Directional factor = 50:50
LDF = 80% of heavy vehicles using outer lane
Question 2
Calculate the cumulative design traffic for a rigid pavement structure using the following design parameters:
Road type: Principal road between major regions
AADT (measured in 2024): 5,000 + the last three digits of your student ID
Year of opening: 2028
HV% = 20
Annual Traffic growth rate= 3%
Annual Heavy vehicle growth rate = 1.5%
NHVAG= 2.2
ESA/HVAG = 0.65
Design period = 20 years
Directional factor = 60:40
Lane distributional factor= 90% of HV using outer lane
Question 3
DCP testing at a greenfield road site produced an average penetration of 60 mm / blow for the nearly saturated subgrade.
a) Use the Harison (1989) formula for DCP / CBR correlation calculate the design subgrade CBR for the road site. (5 marks)
b) Use the Livneh (1987) formula to calculate the design subgrade CBR for the road site (5 marks)
c) Use the TRL formula to calculate the design subgrade CBR for the road site (5 marks)
Hint: a base 10 logarithmic function is used. You can inverse this in excel using = POWER(10, number).
Give your answer to 1 decimal place. E
Question 4
A granular pavement with bituminous seal is to be designed for a collector road in urban area. NDT is 5.0 million HVAG. The ratio of ESA/HVAG = 0.8.
DCP testing at the site produced an average design CBR of 3.0
The following materials are available for your use and are as placed.
Crushed rock, soaked CBR = 90% $60.00/ m3
Coarse river sand, soaked CBR = 30% $45.00/ m3
Clayey gravelly sand, soaked CBR = 15% $20.00/ m3
Silty sand, soaked CBR = 7 % $15.00/ m3
Design eight (8) pavement design alternatives. Note: You do not need to design either seal or other road elements such as slopes, drainage, etc.
Question 5
Based on your pavement designs from the previous question:
Make a recommendation for the preferred pavement design option.
Justify your recommendation taking into account cost, maintenance, and constructability of the pavement.
Question 6
Describe three (2) pavement structure types. Include their application, constructability, relative cost and maintenance considerations
Question 7
List the material parameters used in the current Austroads mechanistic-empirical design methods for flexible pavement design, and outline how these parameters are determined in the laboratory (discuss the relevant test methods) for various pavement materials (including asphalt, stabilised and unbound materials).
Question 8
Explain with sketches, the basis of Austroad’s mechanistic pavement thickness design method (i.e. what theories and assumptions are these methods based on). What is the major difference between the Austroads mechanistic-empirical (CIRCLY) design method and other mechanistic-empirical design methods?