Rail transportation networks can be disrupted from volcanic ashfall due to poor visibility, mechanical impacts and health hazards for train crews and passengers. Moving trains will also stir up fallen ash, which can affect train operations and residents living near railway tracks.
The potential impacts (listed above) can result in the temporary shutdown of rail services or the delay in normal schedules. For example, ten trains in western Montana (USA) were shut down for nearly a day because of 1-2 mm of ashfall resulting from the eruption of Mount St. Helens volcano, 625 km (388 mi) to the west. The rail services were back to normal operations within 3 days.
Following the 2011 Shinmoedake eruption in Japan, the rail network was affected by mechanical failures of the track switches due to tephra build up. The loss of electrical communication contact between the wheels and the track, which occurs at any tephra coverage, results in emergency shutdown of the network until clean up can be undertaken. This resulted in disruptions for up to 8 days following the eruption on various parts of the 146 km (91 mi) affected network.