Pavement thickness design methods have historically been empirically based,
with the performance of pavements being analysed and design charts being
compiled based on the information obtained from the on-site observations of
researchers. This approach led to the publication of Road Note 29 (Department
of the Environment, 1973). This document was based on scrutiny during the
1960s of the behaviour of sections of highway pavement along the A1 trunk
road in Cambridgeshire trafficked by up to 10 million standard axles. It formed
the basis for pavement design philosophy in the UK from then until the mid
1980s.