To visit places within the Garhwal circuit, including the Chota Char Dham, Haridwar is the starting point. The Haridwar Jn. (HW) on the Delhi-Dehradun route has direct trains to major cities like Delhi, Kolkata, Mumbai, Madurai, etc. The Jolly Grant Airport, 44 km from the city provides air connectivity to the rest of the country. Ample bus services are also available from the neighboring states - Uttar Pradesh, Haryana, Punjab - to reach Haridwar.
As I was based in Allahabad, I took the 14163 Sangam Link Express, the only daily train between the two stations. This is a bit slower train and one can also board the tri-weekly 14115 Prayag Ghat (PYG) - Haridwar (HW) Express. The scheduled arrival time for Sangam Express is 10:48 hours while for the PYG-HW Express is 14:15 hours. Taking either of these trains allow enough time to explore Haridwar before heading to the higher altitudes. Additionally, with Indian Railways being well known for their punctuality the time can be kept as a buffer to avoid delay in further plans.