The first parts of the light rail network - called the VLT - are due to enter service on Sunday (June 5) between the Santos Dumont airport and the waterfront.

Olympic organisers hope that the project will help to ease congestion on the city's overcrowded roads ahead of the Opening Ceremony on August 5.

When fully completed, the 28 kilometres tram system will feature six lines and 32 stations, with an estimated 300,000 passengers a day.

The long-distance bus station, main railway station and ferry and cruise ship terminals will be served, as will Rio's historic centre and business district.

Many of the stations will link-up with existing stops on the Rio Metro, as well as bus routes.

When fully functioning, trams will operate around the clock, seven days a week.

The city is running a public awareness campaign to educate Rio de Janeiro residents about the trams.

A reduced service will run in the first five weeks as people get used to the new additions to their streets.

"It is an option for urban mobility with 100 per cent accessibility," Rio de Janeiro's Transport Secretary Rafael Picciani said.

The introduction of the trams comes after a new road to the main venue cluster for Rio 2016 was inaugurated.

The new 3.1 mile two lane elevated section of the coastal Elevado do Joá road will help cut journey times by 60 per cent, it is hoped.

Organisers will welcome both pieces of transport news after it was revealed that a key extension to Rio de Janeiro's subway line would not open until four days before the Opening Ceremony.

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 - on August 1.

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