An investigation has been made into whether pavement stiffness has a significant influence on the energy required to travel along a pavement, and hence whether the construction of stiffer pavements could deliver tangible benefits in fuel consumption. Equipment was developed by TRL to measure rolling resistance in TRL’s Pavement Test Facility (PTF) and during initial tests, this was shown to display the level of accuracy required for such a task. The initial tests also confirmed the expected behaviour, of rolling resistance measurements, when factors such as wheel load, speed and tyre pressure were varied.
Two pavements were constructed within the PTF, both designed to a similar specification to those found on the HA network. One pavement was of a stiff construction, the other flexible and both were surfaced with the same thin surfacing system. Texture, profile and gradient all have a major effect on rolling resistance. Thus the pavements were laid so that the surfaces were as horizontal as possible, which, combined with using the same surfacing course, reduced the effect of differences in these parameters on the measurement of rolling resistance. Hence, the difference in rolling resistance measured on the two pavements would be mainly due to the difference in stiffness between them. A number of trials were then carried out on these pavements to measure this difference.

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