How did the Iron Gate dam change travel through the Danube River gorge?

The construction of the Iron Gate dam, a joint project between Yugoslavia and Romania completed in 1972, fundamentally transformed travel through the Danube River gorge by making a previously dangerous and difficult stretch of the river navigable.123

Before the dam, the rapids and reefs of the Iron Gate made the river nearly unnavigable, requiring rivercraft to be towed upstream against the strong current. The project addressed these hazards by incorporating two locks, each with two chambers, to facilitate safe passage. These improvements had a significant impact on efficiency:43

• Shipping Capacity: The annual tonnage of shipping on the river quadrupled following the project's completion.1
• Travel Time: The journey time for ships traveling from Black Sea ports upstream to Belgrade, Vienna, and central Europe was reduced from approximately 100 hours to 15 hours.3

By taming the river's once-imposing currents and obstructions, the dam integrated this section into a more efficient, continentwide scheme of inland waterways.23