In Istanbul, population growth, road traffic, congestion and pollution are at worst contributing to the rapid decline of the city's liveability, and at best putting at serious risk the city's ambition to be a cultural, economic and logistical hub of Eurasia.
Officially this extraordinary metropolis, on an axis between Berlin and Baghdad, has 13m citizens. Unofficially, however, the population had already reached 15m three years ago, up from 1m in the 1950s. The city's government has set 16m as a sustainable target, but at current growth rates (3.3% per year) the population will be 22m by 2025.
Unsurprisingly, traffic congestion is the leading concern for 55% of Istanbul's citizens, ahead of crime, cost of living and security, according to a 2009 survey commissioned by Urban Age, a thinktank. (By contrast, the issue was a concern for 43% of Londoners and just 16% of São Paolo citizens.) According to Haluk Gerçek, a professor of civil engineering at Istanbul Technical University, 2.7m motor vehicles currently choke the city's roads; between 2005 and 2008 an average of nearly 141,500 more vehicles arrived each year. Commuters driving from Istanbul's Asian side to the European side find that their journey takes more than an hour each way across one of the two existing Bosporus road bridges.
City authorities have plans to relieve congestion. Already, bus-only lanes can carry 500,000 passengers a day and cut journey times by more than one-half. Sibel Bulay, director of the Centre for Sustainable Transport (SUM-Türkiye), says that many business executives living on the Asian side and working on the European side were previously picked up by chauffeurs outside their homes, but now cross the strait by high-speed ferry. The mayor is investing heavily in sea transport.
Such plans, however, risk turning to dust in the hands of at least 20 individual bodies that have power over Istanbul's transport network. Istanbul dominates Turkish politics and society. According to the OECD, the city accounts for one-fifth of Turkey's population, and it generates 40% of the country's tax income. Consequently, Ankara, the country's capital, tends to call the shots regardless of plans made in Istanbul.
Citizens' views on the best way to solve their city's transport woes are disregarded, as different levels of government pursue competing agendas. The Urban Age survey found that only 3% of Istanbul's citizens favour a third road bridge across the Bosporus (compared with 51% who favour expanding the city's public transport network), but the Turkish prime minister, Recep Tayyip Erdogan, insists that it will be built anyway, even though it does not play a part in the city's overall transport master plan. Mr Erdogan himself opposed the third bridge option when he served as Istanbul's mayor between 1994 and 1998.
Such incoherence in planning policy is further exemplified by the US$3bn Marmaray road and rail tunnel project. Due to open in October 2013, Marmaray offers a direct rail connection between Europe and Asia, with capacity more than 10 times higher than that of an existing road bridge and a crossing taking 18 minutes. But Ankara insists that the nearby road bridge also be built.
Professor Gerçek fears that the third road bridge will simply exacerbate Istanbul's decline as a liveable city. He believes that it will destroy a huge amount of the city's forests—its lungs—and water basins, while making no impact on current congestion and promoting further urban sprawl.
"Going beyond a mere pro-growth strategy is crucial," the OECD says of Istanbul, and recommends that city planners take urgent steps to avert threats to social and environmental sustainability posed by uncontrolled migration and traffic growth. Otherwise, the city that is at the core of Turkey's bid for EU membership, a cultural and economic conduit between Europe and Asia, could see both its heritage and future at risk.