The operation of the Blanka tunnel complex in Prague costs the city around 20 million crowns a month, deputy mayor of Prague Petr Dolínek told the Czech News Agency on Friday. The controversial tunnel, which cost the tax payers some 43 billion crowns, was opened on September 19 last year. To date, some 30 million vehicles have passed through the tunnel. The around six-kilometre long underground structure is said to be Europe’s longest urban tunnel.