Advanced monitoring system applied to Colle Isarco viaduct

With its 13 spans and total length of 1028 m, Colle Isarco Viaduct is among the longest bridges in the Alpine region and is a link of strategic importance on the highway corridor connecting Northern Italy to Austria. The bridge was designed and built between 1968 and 1971 and underwent repair interventions in 1988, 1999 and 2007. To cope with today's growing traffic load demand, the bridge was recently further retrofitted through installation of an external post-tensioning system. The effectiveness of this work, completed in 2015, is currently being assessed through extensive structural health monitoring. In this note, we illustrate the bridge, its history and the past maintenance works. We describe in detail the rationale behind the design of the new monitoring system and how the data acquired shed light on the observed past behavior of the bridge and on the effectiveness of the new retrofit intervention.