Metrobus passes over it. Will the viaduct withstand the earthquake?

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Lerato Khumalo

The condition of pedestrian overpasses, bridges and viaducts in the possible “Great Marmara Earthquake” that will affect Istanbul is a matter of curiosity. While seismic strengthening was carried out on the bridges and viaducts on the main arteries of the megacity after the 1999 earthquake, some overpasses and viaducts are still waiting to be overhauled. The route with the busiest pedestrian overpasses in Istanbul is on the metrobus line extending from Zincirlikuyu to Beylikdüzü. The latest images reflected from the Mecidiyeköy Viaduct, where there is no shortage of vehicles at all hours of the day, are causing concern. The corrosion that occurred in some parts of the structure, where seismic isolators were placed to absorb the shaking power of earthquakes of magnitude 5 and above in 2009 and provide the feature of breaking the contact between the earthquake and the structure, draws attention.

The images on the Esentepe section of the Mecidiyeköy Viaduct cause concern.

MUST BE CHECKED

While similar corrosion images do not go unnoticed in the Zincirlikuyu overpass viaduct and the E-5 Mecidiyeköy connection viaduct, it is seen that the irons in the structures are rusting and coming out of the reinforced concrete. City Planner Erhan Demirdizen listed the following warnings regarding the risks especially on pedestrian overpasses: “The most important main artery of Istanbul is the E-5 route. Recently, there are overpasses that have been renewed by IMM after risk assessment. The situation is not like it was 2, 3 years ago. However It is important that Mecidiyeköy and Zincirlikuyu viaducts are inspected regularly. If pedestrian overpasses or viaducts collapse in a possible earthquake, a situation that will tie the hands of emergency teams will arise. “Integrated transportation planning of E-5 should also be reconsidered.”

CORROSION DAMAGE

Former Director of Kandilli Observatory and Earthquake Research Institute, Prof. Dr. Mustafa Erdik is one of the people who pointed out that pedestrian overpasses were among the weakest structures in Istanbul during the earthquake. Prof. Dr. Erdik gives the following information: “We have been warning for years. Even if pedestrian overpasses do not cause loss of life, they must remain standing for the transportation on the main arteries to function. Possible collapses, especially at the crossings on the E-5 route and other main axes, mean that the traffic flow stops. Seismic strengthening was done on most of the bridges and viaducts. However, damage due to corrosion and horizontal load may occur in some structures. Therefore, it would be useful to re-examine all important viaducts.”

WHICH ARE THE STRUCTURES THAT ARE REINFORCED?

On the other hand After the 17 August 1999 earthquake centered in Gölcük, strengthening works were carried out on many bridges and viaducts within the scope of the “Seismic Reinforcement Project of Large Span Bridges” in Istanbul. In this context, especially the 15 July Martyrs Bridge, Fatih Sultan Mehmet Bridge, Old Golden Horn Bridge, New Golden Horn Bridge (East Side), New Golden Horn Bridge (West Side), 1st Bosphorus Bridge Asian Side Approach Viaduct, 1st Bosphorus Bridge European Side Approach Viaduct, Old Golden Horn Bridge Approach Viaduct, New Golden Horn Bridge Approach Viaduct, Ortaköy Viaduct (V 408), Ortaköy Viaduct 36 structures, including (V 409), Mahmutbey Viaduct, Gaziosmanpaşa Viaduct, Sağmalcılar Viaduct, were strengthened.

Metrobus passes over it. Will the viaduct withstand the earthquake? - Picture: 2
There is also corrosion and damage on the viaduct that enters Mecidiyeköy from Esentepe.

MONITORED 24 HOURS

Marmaray is one of the safest structures against earthquake risk. While a 128-channel earthquake monitoring system has been established in Marmaray, vibration and possible earthquake-related shifts in the structure in question are monitored 24 hours a day. Izmit Crossing Bridge, 3rd Bridge, Eurasia Tunnel and metros are among the structures designed to not be damaged in an earthquake.

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