The coastal Elevado do Joá road, which has now been officially inaugurated, has been expanded with a new 3.1 mile two lane elevated section. 

It has been built parallel to an existing two level road which runs by the Atlantic Ocean with two tunnels dug as part of the project.

The road connects the Barra Olympic Park to the Leblon, Ipanema and Copacabana areas of Rio de Janeiro - all major tourist spots.

Congestion on the Brazilian city's roads is a major problem but the 60 per cent figure has now been quoted by the Rio Government.

It is claimed traffic capacity on the route will increase by 30 per cent, with around 85,000 vehicles currently using the route every day between Barra and central and southern Rio.

Two lanes of the road will become "Olympic Lanes" between July 31 and August 22, which will be reserved exclusively for accredited personnel, athletes and officials.

The news comes after it was revealed that a key extension to Rio's subway line would not open until four days before the Olympic Opening Ceremony on August 5.

Improvements to Metro Linha 4, which will link the Games hub at Barra with the city centre, is seen as a key legacy project.

However, it will now launch with just a "soft opening" - for athletes, media, fans with tickets and accredited personnel only.

The extension of the line, westwards beyond Ipanema Bay, is designed to improve the commute for more than 300,000 people a day.

It is also envisaged as the main way in which thousands of spectators will travel between the city centre and the Olympic Park during the Games, taking pressure off a road system which is already a bottleneck in rush hour.

The project has been plagued by delays, however, with concerns peaking in February when a leaked email sent by Rio de Janeiro Mayor Eduardo Paes to the International Olympic Committee (IOC) warned of a "high-risk" it will not be ready in time.