OUESTION $2(25$ marks$)$

a$)$ Design a flexible pavement using the AASTHO approach as set out in the Uganda Roads

Design Manual for the following conditions;$(17$ marks$)$

The region where the road will be located has one rainy season with a total length of

$7$ months,

The subgrade soil is a fair gravel with a soaked CBR in the range $13-16\%,$

The sub base material will be cement treated type C$,$

The most economical material available for the road base will be cement treated

gravel type A $,$

The most suitable surfacing material is Asphalt Concrete

Traffic counts and Axle load surveys have shown that the initial daily number of commercial

vehicles will be as follows:

$2$ Axle and tandem trucks

Trucks with drawbar trailer

Articulated units

Buses

$40$ vehicles$/$day

$22$ vehicles$/$day

$11$ vehicles$/$day

$16$ vehicles$/$day

The economic study has recommended a $20$ year design life and forecast a constant annual traffic

growth rate of $3\%.$

b$)$ Explain the types of pavement distresses resulting from repeated $($cyclic$)$ application of

traffic loads. $(4$marks$)$