Underway since April 2012, the work on the railway track & the Tunnel des Montets has a budget of 77 million euros. The ultimate goal of renovating the line is to have 2 trains per hour.
Between Chamonix and Montroc some parts have been completely changed, both rails and the underlying ballast. But by December 9, the envisaged reopening date of the line to Montroc, everything should be ready.
However, the final opening of the full line (ie 2 trains per hour) will not be until 2015.