In other aspects, the two lines are identical except that the inter-axis width between the tracks on the Green Line is slightly wider than on the Red Line. The construction planning for the Green Line ensures a distance of track centres at including a extra for the kinematic envelope of metro trains. This does not relate to the track gauge of , which is identical on both lines. This will allow wider metro trains be run on the same tracks if a proposed upgrade to full metro service is implemented. This is possible because the route uses an old railway line and as such has few interactions with vehicular or pedestrian traffic. The Railway Procurement Agency has stated (November 2006) that "We still envisage conversion of almost all Luas lines to light metro standard in the long-term.". Platform length also varies between lines, with the original platforms lengthened to on the Green Line