Nextram, which has been developed during the last two years, comprises two main innovations. One is a double-layer concrete trackbed which is only 50cm deep combined with low-height rails. This enables the track to be installed in sections to minimise disruption during construction.\r\nThe other main cost-saving initiative is to use metre-gauge uni-directional LRVs. As these only have one cab and doors on one side, they will be cheaper to build and maintain than dual-direction vehicles. The LRVs would be 23-35m long.\r\nVinci took a 14km line with one depot and a fleet of 20 LRVs to work out a pricing model for Nextram. It estimates such a line would cost \u20ac11-13m\/km to construct, and it would take 10 months to design and around 24 months to build. Vinci says it is vital to get the design and cost structure right at the beginning.