If Crack 1-1 penetrates a deck plate, it threatens not only to cause damage on
pavement but also to deteriorate serviceability and safety to the traffic. What is worse is
that Crack1-1 is invisible until it causes visible damage on the pavement. Therefore PWRI
has given priority to investigate this type of fatigue crack. Crack1-2 is also problematic
because the number of this type of crack is increasing, it is fast growing, and it tends to