The report describes a method by which the effective temperature of a concrete bridge may be determined at any time of day from measurement of the shade temperature and observation of the weather. In order to estimate the temperature of a composite (concrete deck slab on steel box or i-beams) or steel box bridge it is also necessary to measure the movement of the deck during the day. This movement is converted to a change in temperature which is then related to a known datum temperature. The datum temperature is derived from measurement of the shade temperature. If it is not possible to measure the movement of the deck, an alternative, but less accurate, means of estimating the bridge temperature, similar to that used for concrete bridges, is described. Knowledge of this effective temperature enables the bearings or expansion joints to be set at their correct positions within the design temperature range.

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