by AlpTransit Gotthard under contract from the Swiss Federal Government. The axis is the first flat trans-alpine rail link, with a maximum elevation of above sea level. This enables a high-speed link through the Alps with a top speed of , reducing travel time between Zurich and Milan from previously four hours to currently three-and-a-half hours. The Gotthard Base Tunnel is the world's longest and deepest traffic tunnel, as was the original Gotthard Tunnel at its completion in 1881. It consists of two single-track tunnels, connected by 178 cross-connections. There are two emergency stations in each tunnel, each connected to the corresponding opposite-tunnel emergency station. These stations are equipped with water supplies to refill firefighter and rescue trains. One (Porta Alpina) was proposed as an 800m deep rail station, but that proposal was rejected on both economic and technical grounds. AlpTransit Gotthard handed the completed tunnel over to the Swiss government on 31 May 2016. It was formally opened in a ceremony the next day, during which the tunnel was conveyed to its operator: Swiss Federal Railways (SBB CFF FFS). Lötschberg axis The Lötschberg axis, with the Lötschberg Base Tunnel (LBT) in the Bernese Alps, was built by BLS Alp Transit. It supports the western transit network via Basel, Olten, Bern, Brig, Domodossola and Milan. The tunnel replaces the existing higher-altitude 1913 Lötschberg Tunnel for most traffic. The base tunnel opened to traffic on 7 December 2007; it was the first part of the NRLA to be delivered, but is only partially completed. Because of NRLA cost overruns, funding for the axis was diverted to the Gotthard Base Tunnel and only one of the tunnel's two bores has been completed and is fully equipped for rail use. 14 kilometers of the other bore are completed; 14 kilometers are excavated but not equipped, and 7 kilometers have not been excavated. High-speed switches allow the completed third to be used as a passing track, but the of single track without passing loops complicates operations and greatly reduces the line capacity. Trains are scheduled by batches in each direction and separated by long intervals; trains more than seven minutes late are routed via the old line or must wait for the next available timetable slot in their direction in the tunnel, causing major further delays. A planning contract was awarded in 2016 for the completion of the second track of the LBT, which