To protect vibrating wire gauges against damage from construction work and weather, a cover has been designed which permits access to the gauge for manual and automatic readings and which does not interfere with gauge performance. The protected gauges have been used to measure strains on steel plates and stiffeners forming the diaphragm, webs and flanges of the box girder of the Milford Haven Bridge. 94 of the 100 gauges installed were still operating satisfactorily after 16 months use in very adverse conditions.