HELENA – The Montana Department of Transportation (MDT) celebrates “511 Day” (May 11) as Montana 511 marks 13 years of service to Montana citizens and travelers this year. The 511 telephone service officially launched in 2009 as Montana’s traveler information phone number. The free service provides real-time travel information 24/7 including incidents, construction, and weather forecasts. MDT also provides a 511 website, 511MT.net, and a mobile app, MDT 511, which is available for both Android and iOS.