WATER - Under, Over and Through
The Büyükçekmece Bridge

The Büyükçekmece Bridge is sublime, and the work of a genius. Through his design poetry he melded an understanding of geology, soil mechanics, hydraulics, construction, civil and structural engineering, architecture and design.

Sinan registered the bridges he built in his autobiography, with the Büyükçekmece Bridge referenced as “the bridge built in Büyükçekmece”, which means “Great Coming and Going” of waters.

a. The Büyükçekmece [Bridge] is a single bridge. [It is carried] on piers.
b. And the Silivri Bridges
c. The [Coban] Mustafa Pasha Bridge over the Meric
d. And in Marmara, the [Sokullu] Mehmed Pasha Bridge [in Babaeski-Tekirdağ]
e. And three bridges in Halkalı Pinar
f. And over the Harami Dere the Kapıağası [White Eunuch] Bridge
g. And on the Gebze Road, the bridges of Sultan Süleyman.

The Büyükçekmece Bridge opened for use in 1567. The earlier Roman-Byzantine bridge had been destroyed by floods on September 20th, 1563 after a 24-hour deluge and heavy autumn rains (chronicled by Ogier Ghiselin de Busbecq, Flemish ambassador for Ferdinand I of Habsburg to the Ottoman court of Sultan Süleyman I.) The bridge’s arches collapsed under rising water pressure caused by uprooted trees and bushes, timber from demolished buildings and the drowned bodies of cattle, sheep, goats, horses and humans washed down from swollen streams and landslides. At the time, Süleyman I was at his hunting lodge at Halkaderé, a little further inland from Büyükçekmece where the shallow, marshy and almost landlocked cove was a spectacular area for migrating birds. Apparently, he was lucky to survive the deluge.

Financed by the Sultan and his son Selim II, who inherited the throne upon his father’s death, Sinan conceived the new Büyükçekmece Bridge with the knowledge of how the detritus had destroyed the earlier bridge. His concept expressed his aesthetic genius and his profound knowledge of hydrodynamics.

After an examination of area Sinan chose a site further towards the sea where the ground was firmer and the water shallower. Then, instead of a regular set of arches, he envisaged a series of four hump-backed bridges linked by three flat low points some twenty to thirty metres long and not much above normal high-water level. This allows any rising flood waters to pass over these parts of the bridge, creating a negative pressure at the arches blocked on the upriver side with detritus. Thus, the detritus is sucked out from the arches, the water level subsides and the pressure on the shaped stone piers is reduced. People using the bridge could wait at the high points until the low areas were clear of water.

The three low points are built on three irregularly shaped, grassed artificial islands. The islands’ foundations are constructed of waterproof timber coffers, with stones set at their base, and lead poured into the joints between them. The same is true of each pier supporting the arches:
“A cofferdam (sanduka) like a galleon was constructed for each of the piers (ayak), and... drew out the sea water with pumps and large skin sacks and emptied them. And piles made from fine, strong columns the length of two or three men were driven into the foundations with a pile driver, large stones were clamped over them with strong iron clamps (kened), lead was poured between them and they were joined as a single piece.” (SA)

Sinan’s idea was to establish immoveable massive bases. On these bases, the islands were filled with stones inside the timber coffers. The edges appear as solid stone embankments. Sinan understood soil mechanics, which he would have learned when building temporary and permanent structures while in the army and would have calculated for a period of soil stabilisation before loading the foundations of these islands. This may have taken up to two years. He took the same precautions with other buildings - notably the Süleymaniye Mosque – one of the reasons his buildings and aqueducts have survived in a geographic area plagued with frequent earthquakes.

The bridge runs east to west. Travelling from Istanbul the first bridge (158m long) has seven pointed arches rising 7m before falling to the first island, the second (135.5m) is also of seven arches, the third (102m) has five arches and the fourth (184.7m) has nine arches and rises just over 12m above mean water level. Overall the bridge is nearly 670m long and travellers arriving from the west at sunset would be met by the illusion of the seven-metre-wide roadway appearing as four red-gold plates.

Equally, the sight of thousands of plumed Janissary soldiers appearing and disappearing as they crossed the bridge would have looked magnificent when in May 1565 the Sultan and Grand Vizier set out on the road to Hungary – Sultan Süleyman’s 13th and final campaign. The Büyükçekmece Bridge was still unfinished, and its road surface was not yet completed. Sawdust was spread to facilitate a more comfortable passage in a carriage by the infirm Sultan, who was no longer fit enough to ride a horse.

Sinan built a caravanserai and public fountain at one end of the bridge. A masjid (place of worship) was added by the Grand Vizier Sokollu after Süleyman I died during the campaign in Hungary in 1566. It was fully completed in 1568, two years after Süleyman’s death.

On its completion, Sinan signed his work at the west end of the bridge - the only structure or building that is known to have his personal signature: ‘Joseph Son of the Slave of God’. This is not his official Islamic Janissary name, but perhaps being now free of Süleyman, he felt confident enough to sign Yusuf Abdullah and not Sinan abdür-Mennan. The bridge completed the strategic Istanbul-Edirne highway and presented an impressive entrance to the Ottoman capital.

Ian Ritchie’s explanatory sketch of flood water relief through and over Büyükçekmece Bridge

I would love to see the bridge at sunset when the stone ‘planes’ of the bridge would become red and appear together.