The Polyfytos bridge, also known as the High Bridge of Servia, is the second longest bridge in Greece spanning 1,372m in length and is located 15 km southeast of the city of Kozani and 5km northwest of Servia at the Western Macedonia region. The bridge was designed by Ricardo Morandi and constructed from a joint venture Xekte SA – Skapaneus SA. Construction began in 1972 along with the artificial lake and was completed in 1975.  The Lake of Polyfytos is one of the largest artificial lakes in Greece (74 km2 of surface area and max. accumulated volume of 1,220 x 106 m3). The lake was created in 1974 by the construction of the Polyfytos Dam, which impounds the river Aliakmon, by the Public Power Corporation of Greece. The design capacity of the hydroelectric power station at the dam is estimated at 375MW.

The 49-year-old landmark bridge [1] is a long curved prestressed reinforced concrete structure and a key asset providing a crucial connection not only to the capital of the Western Macedonia, Kozani, which is a major energy-production area but also to Athens, the capital of Greece. The bridge is part of the Greek national road E65 connecting major cities (i.e., Athens – Lamia – Larissa – Kozani – Florina – Thessaloniki), while is also used for the daily transfer of people and goods between local communities and towns.

The bridge and its surrounding transport and energy infrastructure exist within a diverse ecosystem exposed to multiple hazards such as extreme temperatures, rainfall, strong winds, wildfires and seismic activity. Given the lifespan of the bridge and the lack of proper and timely inspection and maintenance, the bridge has suffered signs of ageing, corrosion of rebars, concrete spalling and significant permanent displacements of the cantilever spans. Hence, in March 2023, it was deemed necessary for the bridge to be closed for the first time since 1975 to assess its structural integrity and reopened in May 2023 with reduced operability and load traffic capacity.

Our project partners from the University of Birmingham and Brunel University have extensive experience studying the landmark bridge and assessing the climate impact on the deterioration process including the scouring effect due to the frequency of flooding events. The Polyfytos bridge has also been the testing bed for applying new digital technologies such as laser scanners and photogrammetry methods, which allowed to create an accurate 3D Finite Element Model for further analysis. The 3D model, with the collection of monitoring sensor data, created a digital twin of the bridge to enhance climate resilience.  The bridge is also one of the pilots in the Horizon project resulting in many relevant publications, as listed below.

ReCharged aims to advance the existing research work on Polyfytos bridge by examining the complex interdependencies between the critical asset with the remaining transport and energy network of the region, which can be applicable to any other similar cases worldwide. Polyfytos bridge will be also part of a visualization platform designed to address awareness of climate risk and support decision-making on climate resilience of critical transport infrastructure.

[1] The bridge has a mixed structural system, consisting of simply supported I-beams and monolithic cantilevers with variable cross-sections and variable pier sections. It is curved in plane and has a prestressed reinforced concrete deck of 13.4m width with 29 spans. The first 25 spans are simply supported on the piers consisting of three precast prestressed I-beams and cast in situ slabs with expansion joints placed at every pier. The remaining four spans, which are the longest and located over the tallest piers, are constructed by balanced 30m long cantilevers that support 40m long simply supported precast beams.  The piers have an octagonal hollow core cross-section, and their heights range from 15m to 50m. They are typically founded on spread footings (11.5m x 15m) on a 5m compacted gravel layer over limestone. While two of the piers located in the riverbed are founded to alluvial deposits with 22 piles (1.2m diameter and varying depth from 16m to 19m); the embankments are of gravel and are founded on hard clay.