Field Observation of Tagus River Suspension Bridge

The field observation of the Tagus River suspension Bridge was started by the LNEC Division of Observation of Structures in 1961, and has been its main activity thereafter. The aim of the observation is to determine the actual behavior of the structure under the action of different types of loadings in order to estimate the overall safety conditions in it. In addition to preparing the overall plan and part plans of observation of the suspension bridge and of different approach viaducts, the majority of the equipment required had first to be designed and manufactured. The instruments, some of them original, were constructed at the LNEC Division of Observation of Structures and of Instrument Design and Construction. The field observation of the structure can be divided into three stages: measurements during construction, load test (July 1966) and long-term observation up to 1971. The techniques followed and the results obtained in the suspension bridge and the approach viaducts are presented.