15 July Martyrs Bridge is the first suspension bridge that connects Asia and Europe by road over the Bosphorus in Istanbul, with a length of 1,560 meters, a width of 33.4 meters, and a span of 1,074 meters between towers. The 15 July Martyrs Bridge, the first highway bridge built over the Bosphorus in Istanbul, was opened to service in 1973 under the name “Bosphorus Bridge”, but following the intense clashes and civil resistance during the coup attempt on 15 July 2016, its name was officially changed to the current one on 25 July 2016. This name change represents the repositioning of the bridge not only as a transportation infrastructure but also as a symbol of resistance, the struggle for democracy, and national unity in the collective memory.

History

The idea of building a bridge over the Bosphorus in Istanbul has arisen in different periods throughout history. It is accepted that in the 6th century BC, Persian King Darius crossed the Bosphorus with a bridge made of ships and rafts to move his army to Europe. The floating bridge built under the leadership of engineer Mandrokles during this passage holds historical significance as the first artificial crossing established over the Bosphorus. During the Renaissance, Leonardo da Vinci is known to have proposed to Sultan Bayezid II a bridge over the Golden Horn, and by the end of the 19th century, engineers like Ferdinand Arnodin submitted railway bridge projects between Sarayburnu–Üsküdar and Rumelihisarı–Kandilli to the Ottoman authorities.

During the Republican period, especially Nuri Demirağ’s attempts in the 1930s to build a suspension bridge similar to the Golden Gate for the Bosphorus crossing drew attention. From the 1950s onward, the increasing population, rapid urbanization, and transportation needs made the construction of a bridge necessary. In this direction, in 1957, a technical project was prepared by American D. B. Steinmann, but the process halted with the 1960 coup. Finally, in 1968, a contract was signed with Freeman, Fox and Partners; the construction tender was won by a consortium formed by Hochtief A.G. (Germany) and Cleveland Bridge (United Kingdom).

Construction Process and Technical Specifications

In 1967, Turkey requested four engineering firms with global expertise to prepare projects for the Bosphorus crossing. At the end of this process, an official agreement was signed in 1968 with the British company Freeman, Fox and Partners, which submitted the most suitable proposal. The construction tender for the bridge was won by a consortium formed by Germany-based Hochtief A.G. and UK-based Cleveland Bridge and Engineering Company.

Construction of the bridge began on 20 February 1970, and the project was completed in approximately three years. The opening took place on 29 October 1973, marking the 50th anniversary of the proclamation of the Republic. According to data from the General Directorate of Highways, the construction cost of the bridge was determined as 23,213,666 US dollars.

The construction process was carried out in three main sites: Ortaköy, Beylerbeyi, and Küçüksu Meadow. The steel decks of the bridge were produced in a temporary factory-workshop established in Küçüksu, and the foundations of the piers were excavated simultaneously on the Ortaköy and Beylerbeyi sides. The tower assembly was completed on 4 August 1971; and in January 1972, the pilot rope was successfully pulled. The steel suspension cables used on the bridge were formed by combining wires pulled individually, reaching up to 70 wires per day and exceeding international engineering targets.

^{July 15 Martyrs Bridge Construction (Sanal Şantiye)}

The approximate quantities of the main items used in the construction of the bridge are as follows:

• Excavation: 63,000 m³
• Concrete: 71,000 m³
• Reinforced concrete steel: 4,000 tons
• Structural steel: 17,000 tons
• Cable steel: 6,000 tons

Upon completion, the bridge was considered among the engineering achievements of its time with a total length of 1,560 meters, a span of 1,074 meters between towers, a width of 33.4 meters, and a height of 64 meters above sea level. The structure initially included three-lane roads in both directions and pedestrian walkways. However, in 1978, pedestrian access was closed due to security concerns.

Technical Renovations

In the analyses conducted between 1973 and 2006 on the structural behavior of the bridge, differences in horizontal and vertical displacements were observed depending on temperature changes, traffic loads, and maintenance activities. In the suspension cable renewal project that began in 2014, materials suitable for the existing structure were selected, connection details were made more rigid, and damping capacity was improved. Thus, the bridge’s long-term load-carrying capacity and fatigue resistance were enhanced. The structural behavior of the cable system was analyzed using numerical modeling. In the new design, higher rigidity and energy absorption were achieved, and vibrations were minimized.

Logistical and Economic Function

The 15 July Martyrs Bridge is considered one of Turkey’s most strategic transportation infrastructures, as it is the first structure to directly provide road transportation between the Asian and European sides of Istanbul. Beyond being the first bridge to handle vehicle traffic across the Bosphorus at the time it was built, it also formed the backbone of Istanbul’s intra-city and transit transportation plans along with surrounding highways.

^{July 15 Martyrs Bridge (Anadolu Ajansı)}

After being opened to service in 1973, the bridge became, both directly and indirectly, part of economic and logistical systems alongside the rapid urbanization of Istanbul. Especially with its integration into the FSM and TEM connection roads managed by the General Directorate of Highways, the bridge became not only a part of urban traffic but also of regional and national logistics routes. Over time, the commercial vehicles passing over the bridge became a significant component of national transportation along the west–east axis rather than of Istanbul’s inner-city traffic.

The revenue generated from bridge crossings has made a significant contribution to public finance. The gross income earned by the state from bridge tolls has been monitored more systematically since the 1990s, particularly with the highway–bridge privatization policies; and by the 2000s, the income generated from bridge crossings began to be used for financing maintenance, renovation, and new investments.

The logistical and economic function of the bridge is not limited to its transport capacity alone. The toll area of the 15 July Martyrs Bridge has over time become a serious traffic bottleneck, and this situation has necessitated various regulatory efforts. Indeed, in his statement, Minister of Transport and Infrastructure Uraloğlu indicated that the number of vehicles passing over the 15 July Martyrs Bridge in a single day in 2024 was 190,000.

15 July 2016 Coup Attempt

During the coup attempt that took place on 15 July 2016, the Bosphorus Bridge became one of the areas where the events occurred most intensely and symbolically. At 21:23, military units from the Kuleli Military High School Command departed and arrived at the bridge at 21:52, blocking traffic unilaterally in the direction from Anatolia to Europe. After this closure, various confrontations occurred between military units and civilian citizens and security officers who arrived at the scene in the following hours. Over time, tanks and armored vehicles dispatched to the bridge reinforced the military control on the bridge.

^{July 15 Martyrs Bridge (Anadolu Ajansı)}

Throughout the night, gunfire was reported at various points on the bridge; it was documented that cannon shots were fired at water cannon vehicles (TOMAs), security forces’ vehicles were seized, and firearms were used directly against civilian crowds beyond mere warnings. According to the indictment prepared by the Istanbul Chief Public Prosecutor’s Office, the events on the bridge lasted a total of 8 hours and 23 minutes. As a result of the events, 34 people—2 police officers and 32 civilians—lost their lives. In incidents that occurred the same night on the Fatih Sultan Mehmet Bridge, it was reported that 3 people died.

Around 06:15, the military units on the Bosphorus Bridge surrendered without weapons. Some of the surrendered soldiers were physically assaulted by civilians, after which the security forces intervened and took the soldiers into custody. Ammunition and vehicles found at the scene were confiscated. According to the indictment, a total of 318 people were subjected to attempted murder during the coup attempt; many public vehicles, buildings, and civilian vehicles were damaged.

Following these developments, the name of the Bosphorus Bridge, which became one of the recorded locations of the coup attempt, was officially changed to “15 July Martyrs Bridge.”