Bridges that link areas and decrease traffic congestion are necessary but it is equally important to maintain them to avoid tragedies. A few weeks ago Infrastructure Malta completed the first restoration stage of the Mistra Bridge which was in danger of collapsing and currently technical studies are being undertaken on the bridge between Qormi and Marsa on which there is the Marsa- Ħamrun Bypass. TVM spoke to the architect and structural engineer Dr Konrad Xuereb regarding the maintenance of bridges and whether these can bear the great number of vehicles that use them daily.
With the help of Maltese and foreign experts, Infrastructure Malta has commenced a technical study so that repaid and maintenance work can commence on the bridge that is near Maltapost and along which runs the Marsa-Ħamrun Bypass. Thousands of vehicles use this bridge on a daily basis and over a period of time their weight began to crack the concrete. It is also evident that parts of this bridge are undergoing rapid deterioration.
According to Dr Xuereb, this and some other bridges were built approximately 50 and 60 years ago and are very delicate structures, built at a time when there was less onerous legislation to regulate their design. Today these older bridge structures are past their original anticipated design life.
Dr Xuereb said that we are the first generation that is experiencing the end of the anticipated design lifespan of these older bridges and concrete structures, including for example reinforced concrete balconies.
Concerns have increased about these structures following the collapse of part of Genoa’s Morandi Bridge last Tuesday. Similar to the Qormi-Marsa Bridge there are other old bridge structures including that just before entering the Regional Road and Mistra.
Dr Xuereb explained the inspection and maintenance regimes on new bridges, such as the new Kappara Flyover is as establishes according to modern codes of practices for new bridges, with a first inspection typically after ten years and then bi-annually. He said that new bridges are typically designed to have a design lifespan of 100 to 120 years. For old bridges, different inspection regimes and maintenance works are required depending on the condition of the bridge structure.
He said that the type of inspection depends on whether it has to be a general inspection or a principal inspection the bridge engineer then advises the relevant authorities if further repairs works and monitoring are needed. On older bridges, the inspection is far more frequent and detailed compared to newer bridges structures.
Dr Xuereb said detailed inspections would determine whether a bridge should be restored or whether financially it would be more beneficial to construct a completely new bridge. He referred to a similar case in England when the Hammersmith flyover Bridge in central London was closed for two years for extensive repair works. Recent repair works on the 2.2km suspension Humber Bridge in Lincolnshire were also referred to by Dr Xuereb.