The Thai capital Bangkok has unveiled the first stage of a mass transportation system which it is hoped will make the city's infamous traffic jams a thing of the past.

A further year of tests is needed before the public opening of the elevated electric railway built through 23km of the city centre.

A school brass band provided a not always tuneful accompaniment to the unveiling of Bangkok's long-awaited Sky Train system.

The first stage of the Sky Train under test

It has taken almost five years to build the $1.2bn concrete viaduct extending down some of the city's biggest and most congested thoroughfares.

The train glides smoothly along a track suspended about 12 meters above the road.

But extensive safety and environmental tests have still to be done before the Sky Train can begin commercial operations or become, as it is intended, the central section of a much larger and more ambitious mass transit network.

Extension

The government is pressing the Sky Train's private owners to extend the line further into the northern and southern suburbs, otherwise they fear middle class Thais will see no advantage in leaving their cars at home and using public transport instead.

Several hundred curious Thais joined the dignatories for Tuesday's trial run.