 Trams were chosen because they appeared to be more reliable than buses, since they are not subject to the vagaries of traffic, but they are less expensive than a subway line.The tram was declared a public utility in 2003 and work began the same year; the line was placed in service on 24 November 2007 after several weeks of technical trials, even though construction was not fully completed.In the months following the launch of the tram, there were between 65,000 and 70,000 passengers daily; the number rose to 90,000 by January 2011.