One train definately needed via shiradi ghats from chennai as there is no connectivity there. It can be for mangaluru or via KR any destination. SR never cares to run such as it feels routing via CLT attracts more revenue. Technically ghat section adding difficulty,+ via CLT u can easily take 22 coacher train which via hassan we have restriction of 14/16 i suppose. so y to sacrifice extra revenue when running time is similar.