Phases two and three may be performed concurrently or separately. The cost of completing work on the LBT has been estimated to be around one billion Swiss francs. The project also includes two parallel bridges over the river Rhône in canton Valais, the Engstlige tunnel (built with cut-and-cover method; the two tracks are separated by a wall). A planning contract for phases two and three was awarded in 2016 to the Swiss engineering consortium IG Valbt, headed by SRP Ingenieur. The resulting plan was presented for review in early 2019. At the time, construction was expected to start around 2021/2022 and was projected for completion by the end of 2028.