The primary objective of the project was to develop data and methods for predicting the durability of highway structures in advanced composite materials. A test program was carried out to investigate the long term performance of a full scale prototype of a highway structure weathered in a natural environment. In parallel to this work a comprehensive test programme on small scale samples was carried out to determine the short and long term mechanical properties of advanced fibre reinforced composite materials under both natural and accelerated weathering conditions. The objective of the materials testing was to determine the dependence of mechanical properties, such as strength and rigidity, on age, previous temperature history, humidity and ultra violet radiation. The data obtained allowed primary structures to be designed to meet stringent durability requirements in demanding service environments.

The full scale prototype structure was an 18m simply supported beam structure that can be used as a highway footbridge. It consisted of a multicellular box structure constructed from ten 18m long planks resulting in a beam cross sectional area of 2.12m by 0.76m. The Advanced Composite Construction Sysytem (ACCS) planks, the Maunsell Plank, were formed by the pultrusion process, and when bonded together formed a three dimensional shell structure weighing only 3 tonnes. The beams were subjected to a nine month creep test in a natural environment under a full design load of 20 tonnes. This was achieved by stressing two of the box beams back to back under four point loading. The reduction in short-term stiffness, one measure of mechanical degradation, was monitored at intervals throughout the creep test and found to be insignificant. After the creep test, one of the prototype beams was subjected to a comprehensive range of tests in the laboratory, including dynamic, vibration and a flexural test to failure.

The ACCS system in this configuration was ultimately used to construct a 9m lift bridge on the Stroud Navigation at Bondsmill; the Structural Composite Research Unit monitored this bridge for structural performance for a period of one year.