Testing of the LRVs began on a 500m track section from Gogarburn station to the depot in December 2011 and was extended to the 2.8km section from Gogarburn to Edinburgh Airport in November 2012 when 750kV dc overhead electrification work was completed on this section.
The test programme on the new 4.9km section will peak at 150 journeys along the line, five days a week, which the council says will enable city residents to get used to the new service. Testing on the remaining km 8.6km section through the city centre is expected to begin in December.
Construction of the city's inaugural 16-station light rail line got underway six years ago, but political wrangling resulted in numerous delays, project downsizes and cost overruns. The revised budget, which was approved in September 2011, now stands at £776m, significantly higher than the £375m estimate at the start of the project in 2003.
"The target for service launch is now May 2014, but we'll bring this forward if we can," says city councillor Ms Lesley Hines, Edinburgh's transport convener. "However, it is important to recognise the significance of this testing, commissioning and driver training programme. There is much to be done and it's vital that all the appropriate tests and checks are made."
CAF, Spain, is supplying 27, 42.8m-long low-floor LRVs for the line, the first of which was delivered in April 2010.