South of Zurich and west of Andermatt, the Loipen Urserntal cross-country skiing trail system is a groomed track linking Realp with Hospental and Andermatt for a 18km trek. The tracks are groomed for both classical and skate skiiing, and has a few side tracks to explore. Overall, there are 28km of groom tracks along the Reuss ranging in elevation from 1,425m to 1,630m. A trail pass is required to use this trail system. Note, there are no nordic centers, ski rentals or trail pass vendors on the trail system. These services are only available in the town of Andermatt.
To reach Realp cross-country skiing from Zurich by train, you'll take the regional train through Luzurne to Goschenen. In Goschenen, you will switch to the Matterhorn Gotthardbahn cog railway for a 15 minute ride up to Andermatt. In Andermatt, you can change trains to the Matterhorn Gotthardbahn heading west to Realp.
To reach the cross-country skiing in Andermatt from the east in the Canton of Grabrunden, you will need to pickup the Matterhorn Gotthardbahn railway starting in Ilanz. It will run west through Disentis and Sedrun heading over Oberalppass to Andermatt. In Andermatt, you can change trains to the Matterhorn Gotthardbahn heading west to Realp.
Tip - Realp is home to a famous biathalon. Make sure to book far in advance if you plan to come during the events.