At 00:50 the train restarted towards the adjoining Bella-Muro station, and reached a speed of about 15 kilometres per hour (9.3 mph).[1] After 1.8 kilometres (1.1 mi) of travel, it approached the Armi tunnel, narrow and poorly ventilated, which is 1,968 metres (2,152 yd) long with a 1.3% incline. As the engines entered the tunnel, the wheels started to slide on the rails (which were wet due to humidity), despite the use of sand boxes, and the train lost speed until it stopped, with almost all the cars inside the tunnel.[4]