The first bridge of the Bosphorus, formerly known as the Bosphorus Bridge, now known as the 15 July Martyrs’ Bridge, crosses thousands of cars from one continent to another every day. The bridge, which was first opened in 1973, had passed an extremely strange test while it was still under construction, the ethics of which are debated even today.
Today, we will tell you about the static loading tests carried out 15 days before the July 15 Martyrs Bridge was opened to traffic on October 30, 1973. The experiments, which tested the weights of the bridge, which was called the Bosphorus at that time, were carried out without taking any serious precautions. Let’s talk about the interesting experiment that this legendary bridge, which has 50 stairs, went through at the beginning of its life.
How did the static loading tests of the 15 July Martyrs (Bosphorus) Bridge take place?
The Bosphorus Bridge, which was designed to carry the load of countless vehicles every day, was put into static loading tests at the request of the British consultancy firm Freeman Fox. Highways decided to apply an extremely interesting method for these experiments. On October 15, 1973, the driver of about 140 trucks waiting in line on the Kabataş car ferry said, “The bridge has opened, you will pass there now.” they actually directed the trucks to the unopened bridge.
140 trucks and their drivers, who were unaware that they were in an experiment, were loaded to make 2.5 lanes on the bridge. After the experiment on the Beylerbeyi side, which lasted about 1 hour, the trucks were unloaded and placed on the Ortaköy side in the same order. After the experiments, which lasted for a total of 1.5 hours, no other trucks were passed over the bridge until the opening.
What was the purpose of the experiment?
By placing weights on both sides of the bridge, the teams measured the maximum strains and maximum steel stresses with strain gauges placed in various parts of the bridge. As a result of the measurements, it was determined that the maximum collapse in the first part of the bridge was 123 cm. In the second stage of the experiment, the maximum collapse was determined as 124 cm. In the first stage, which caused a 123 cm collapse in these measurements, the bridge was loaded with a load of 1679 tons. Accordingly, it has been calculated that the bridge will carry a load of 2650 tons that it can safely carry from tower to tower. It was calculated that the bridge would reach a serious collapse value of 190 cm under this load.
In order to reach 2650 tons, which is determined as the safe traffic load for the Bosphorus Bridge, it will be sufficient for trucks with an average weight of 20 tons and an average length of 10 meters to fill 1.5 lanes by placing them on the bumper. If only 3 lanes of the Bosphorus Bridge, which has 6 lanes in total, were filled in this way, it would make a load of 6440 tons, which is enough weight for the bridge to collapse.
How does the July 15 Martyrs Bridge cope with this weight today?
As you can see, the Bosphorus with its old name, the 15 July Martyrs Bridge with its new name, is an extremely old bridge. The weights it can carry are also in the middle. Considering the increasing traffic density in Istanbul, various measures need to be taken in this regard. Today, vehicles with large tonnages such as trucks and trucks are prohibited from crossing the bridge, except for municipal and public buses.
So how did you find the experiment on the 15 July Martyrs Bridge? Although it is close to 50 years old, you can share your thoughts about this bridge, which has undergone various controls, in the comments section.
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