At what altitude is the world's highest bridge?

The highest railway bridge -- Sanchahe Bridge, 690.19 meters long, is located over a canyon with an average altitude of 3,800 meters. The floor of the bridge is 54.1 meters from the bottom of the canyon." This bridge is on the Qinghai-Tibet Railway, the longest and highest railroad in the world.

The highest bridge in the world can be found in the Ladakh valley between the Dras and Suru rivers in the Himalayan mountains. The valley lies at an altitude of about 5 602 m (18,379 ft) above sea level on the India side of Kashmir. It is a Bailey bridge, only 30 metres (98 ft) long, built by the Indian Army in August 1982. The highest bridge is on the highest road in the world, which runs along the Himalayan ridge in the Ladakh valley in Kashmir.

A Bailey bridge is a temporary bridge of lattice steel designed for quick assembly from prefabricated parts. The design is famous for its military application. In fact, its designer, Donald Bailey, worked for the British War Office during the Second World War when he proposed the design, the first of which was used in the North Africa campaign in 1942.