JNPT to ICD in TKD. This is main flow, most volume of concor traffic through India. Besides freights between Rajasthan and Mumbai, foodgrain transport, coal to TPPs in Kota, Suratgarh etc(from east).
Edit: Forgot to Mention ports of Kandla, Manglore, Cochin also have some scheduled freights on this section(being the fastest freight transporter) to northern parts of India and freights from Punjab to South.