Britain's Queen Elizabeth opens Scotland's third Forth bridge

LONDON, Sept 4 (Reuters) - Britain's Queen Elizabeth formally opened Scotland's biggest infrastructure project in a generation - the third bridge across the River Forth - on Monday, exactly 53 years after she opened the second.

The 91-year-old monarch met with workers and school children who had gathered on the bridge before cutting a blue ribbon to mark its opening, as a flotilla passed underneath and the Royal Air Force's Red Arrows display jets flew overhead.

The 1.35 billion-pound ($1.7 billion) Queensferry Crossing, the longest bridge of its type in the world at 1.7 miles (2.7 km), connects the capital Edinburgh to Scotland's north.

The Queen described all three "magnificent structures" crossing the River Forth, built in three separate centuries, as "feats of modern engineering".

"The Queensferry crossing joins its iconic and historic neighbours to create not only a breathtaking sight across the Firth of Forth, but to provide an important link for so many in this community and the surrounding areas," she said in a statement.

Built with 35,000 tonnes of steel and 150,000 tonnes of concrete, the crossing reaches 210 metres (690 ft) above high tide, standing as tall as about 48 London buses stacked on top of each other. Barriers deflect the wind and shield vehicles from the huge gusts common on the Forth.

(Reporting by Emma Rumney, editing by Ed Osmond)