Flexible pavements are relatively thick in Hong Kong which their thicknesses are generally designed to be at least 300 mm, generally due to high traffic volume. The design is based on the fatigue failure concept of the main structural layer (i.e. roadbase) after a prolonged number of traffic passages, and in turn, it is highly related to the stress levels being experienced in the pavement layers including the subgrade. This paper presents the data collected, being the first time in Hong Kong, on the dynamic stresses of the subgrade layer by soil pressure gauges under a major highway in Hong Kong. The results illustrate that the vertical stresses are being in the range of 0.5 to 5 kPa. These correspond well to the theoretical analysis results being obtained by the software mePADs, by using the typical properties of the pavements layers. Subsequently, horizontal stresses at the bottom of the roadbase were also estimated. These fundamental findings provide an important yardstick for the review of design and analysis for fatigue life of flexible pavements in Hong Kong.
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