Sitting in front of an array of video and computer monitors, Capt. Aziz Yildirim can track the path of every vessel sailing through Istanbul's Bosporus strait with pinpoint precision. Today, though, the most noticeable image on his screens is stuck: a large blob, representing nearly 100 ships, is idling at the straits' mouth.
"They have to wait their turn," says Captain Yildirim, a supervisor with Turkey's Vessel Traffic Service. "Everybody knows the Bosporus - it's a dangerous place."
It's crowded, too. An estimated 50,000 vessels - many of them loaded with combustible oil or natural gas - sail through this strategically important waterway that cuts through Istanbul, dividing Europe and Asia. And 2.5 million commuters ferry across each day.
To prevent a major accident on the strait, Turkey last year upgraded its tracking system and set up new traffic controls. Turkish officials say the move has improved safety. Critics say the new system has created a Bosporus bottleneck, increasing the cost of shipping and holding up the delivery of oil and gas from Russia and Central Asia.
As regional oil and gas production ramps up, so will shipping traffic. That expansion, say observers, could make a waterway accident more likely, but also increase tension between Turkey and its neighbors, particularly Russia, who rely on the Bosporus for their shipping.
"We're at a turning point. The Turks are saying 'We can't handle all this oil traffic,' and the Russians are complaining, so we need to figure out what to do," says Bulent Aliriza, director of the Turkey project at the Center for Strategic and International Studies in Washington.
Zigzagging a north-south course past graceful Ottoman palaces and modern apartment blocks, the Bosporus flows for 20 miles, connecting the Black Sea to the Sea of Marmara and eventually the Aegean and Mediterranean. Its currents are notoriously fickle and in winter it is often shrouded in fog.
The 1936 Montreux Treaty guarantees unhindered passage through the strait to all commercial shipping. At the time, though, the largest tankers weighed 10,000 tons. Today, 200,000-ton tankers regularly sail through.
Until recently, ships would freely come and go, but Turkey's new regulations limit the passage of tankers carrying hazardous materials to daylight hours, and also increase the distance between every vessel entering the Bosporus.
"What the Turks have done is that they have used traffic management to limit traffic flows, rather like putting speed bumps on a congested highway," says John Roberts, a London-based energy security specialist at Platts, a company that analyzes the energy market.
Sitting in an office that overlooks the Bosporus and Istanbul's harbor, shipping agent Ibrahim Koral fields calls from anxious oil-company executives, eager to know when yet another bout of fog will lift and their anchored tanker will be able to continue through the strait.
"They're not happy," says Mr. Koral. "They want to be able to enter day and night." Before, under normal conditions, tankers were able to make the trip from the Aegean to the Black Sea and back in 12 days," Koral says. Last year, the combination of new regulations and frequent bad weather meant that same trip sometimes took up to 44 days, he says.
Turkish officials, however, say the recent regulations are an absolute necessity. "It's not only a seaway or a strait, it's the main boulevard of Istanbul," says a Turkish foreign ministry official.
"We can't just keep saying 'God willing nothing will happen,'" the official says. "In the worst-case scenario, it would be the loss of irreplaceable cultural treasures and the loss of thousands of lives."
To avert this kind of disaster, Turkey is pushing for the creation of a land-based oil pipeline that would bypass the Bosporus.
"If a bypass pipeline is not built, the tensions are bound to increase," Mr. Aliriza, the Turkey analyst, says.
There are currently five possible routes under discussion, but Turkey first wants oil companies to voluntarily commit to pumping their product through whichever pipeline is finally built, to avoid a scenario in which one company picks up the shipping slack of those that are no longer using the Bosporus.
"Everybody needs to share the burden," says the Turkish official.
Aliriza says even Russia, which has been the most resistant to Turkey's new shipping regulations, has come to accept the need for a pipeline. "There is a broader rapprochement between the Turks and the Russians, so instead of fighting about it they are talking it through," he says.
In the meantime, it appears that the traffic situation on the strait will only get more intense. "The Bosporus can only contain so much," says Koral, the shipping agent. "It's not going to get wider."