"We see 150 vessels pass through the strait every day and as many as 9567 tankers per annum," said Captain Olcay Ozgurce, head of the Vessel Traffic Service (VTS) of the ministry of transport's directorate general of coastal safety. In other words, the Istanbul Strait hosts 54,750 ships per year, of which 17.5% are tankers.
Maritime congestion has clearly worsened. Between 1994 and 2002 around 48,200 ships passed through the Turkish straits - a reference to both the Bosphorus Strait and Dardanelles Strait - per year, according to government figures.
Comparison of traffic levels from various maritime arteries in the world underlines the danger of ship collisions in the Istanbul Strait. While the Panama Canal saw the passage of 12,755 ships per annum between 1999 and 2000, the Suez Canal registered 13,552 compared to the Keil canal with 23,945. Only South East Asia's Malacca Strait with its 100,000 ships per year beat Istanbul's 48,000 between 1999 and 2000, according to official statistics.
But a combination of sharp bends, strong currents and winter fog make the Bosphorus particularly dangerous for vessels. Of the 12 sharp turns along the Istanbul Strait, that between Kandilli on the Anatolian side of Istanbul and Asiyan on the European side counts as one the most treacherous, with ships having to swing a rapid 45 degrees with as little as 698 metres separating the two shore lines. Vessels have to make the biggest rotation off Yenikoy, turning 80 degrees. "A slight miscalculation in seamanship can have serious repercussions, with strong tides magnifying the effects of error," said an Istanbul-based maritime analyst.
The waterway has had its fair share of close calls, many of which are not covered by the press. "In 2006 we had 163 failures on the Istanbul Strait, these being mostly machinery and rudder failures, compared to 138 failures in 2005," said Captain Ozgurce.
By the end of August 2007, VTS already recorded 141 such incidents for this year. Among the biggest ship accidents in Turkey's contemporary history were those in 1979, 1994 and 1999, the most recent of which was the grounding of a Russian tanker, spilling 235,000 gallons of fuel and leaving 10 km of coastline blackened.
Energy delivery thus accounts for much of the headache. According to energy analysts, 3m barrels of oil pass through the Bosphorus every day. The Baku-Tbilisi-Ceyhan oil pipeline running from Azerbaijan to Turkey's south eastern coast appears not to have alleviated the energy risk on the Istanbul Strait, where Russian and Ukranian ships - from a longer list - sail through a city containing 12m people.
That Turkey must allow 'innocent' passage to foreign commercial vessels - that is free passage in line with the original commitments of the 1936 Montreux Convention but subject to national safety regulations - is an important point. While international law characterises the straits as international waterways, Turkey's geography allows it to impose certain safety regulations on vessels seeking passage.
Tankers longer than 200 metres for instance are barred from passing at night while large vessels must submit their sailing plans in writing 24 hours before passing. "We have had one-way traffic for around two years now, switching roughly every 12 hours, due to the Marmaray project (the rail project running beneath the Bosphorus)," said Captain Ozgurce. "This is something we will probably keep to bolster safety." Vessels can also be forced to stay anchored at either end of the Istanbul Strait due to bad weather conditions with demurrage costs amounting to $35,000 to $75,000 per day, depending on the cargo.
This is not to say that Turkish authorities are fully satisfied with the regulatory power that they enjoy, particularly given the increased level of traffic over recent years. While the VTS strongly recommends that vessels hire qualified local pilots, they can not oblige ships to take them on board. Statistics from the VTS reveal that a mere 48.4% of all vessels host Turkish trained pilots, heightening the risk of collision or groundings.