Page 102 - Lecture Notes DCC3113

Example

120 kN 100 kN 80 kN

The total mass of a commercial vehicle is 300kN and is transmitted to the pavement via three axles. The
first axle is 120kN, second 100kN and the third is 80kN. The value of equivalent factor, F.

F = (L/Ls)
4
F = (120/80) + (100/80) + (80/80)
4
4
4
F = 8.50

7.2.3 The Public Work Department flexible design pavement method.

Malaysian Design Methods

Adopt design method based on AASHTO Guide, and catalogue of structure method:
i. Arahan Teknik Jalan 5/85 – based on AASHTO road test, developed using multi-layered
elastic theory. Suitable for major roads with heavy and medium traffic
ii. Overseas Road Note 31 – based on research in tropical and sub-tropical countries

Pavement thickness Design Arahan Teknik Jalan 5/85

Data required:

i. Design life, x – suggests 10 years
ii. Class of roads
iii. Initial Annual Daily Traffic – AADT (Veh/day)
iv. Percentage of Commercial Vehicle - Pc
v. Average annual traffic growth - r
vi. Sub-grade strength - CBR
vii. Terrain condition

Design Procedure:

i. Calculate Initial Annual Comercial Vehicle Traffic per direction, Vo

Where AADT = average annual daily traffic (veh/day) in both direction
Pc = percentage of commercial vehicles
D = Directional distribution (0.50 if directional split is 50:50)
L = Lane distribution (1.00 if single lane)

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