Extending Kannur - Alappuzha - Kannur Executive Express and Chennai Central - Alappuzha - Chennai Central Express to Trivandrum has sure shot benefits.
1. Vanchinad Express which arrives TVC @ 10:00AM can leave as Executive Express @ 12:00pm which will surely share the load of daytime passengers in Kerala and Island Express. Also after Netravati Express the next daily train towards Alappuzha is Kochuveli - Mysuru Express.
So...
more... this would help those going towards Alappuzha. Also a better option to Kannur than JS which reaches Kannur around Midnight.
2. Kannur - Alappuzha Express can be made to reach TVC around 3:30 which can return as Vanchinad Express. An afternoon connection between KYJ and TVC and another daily connection between ALLP and TVC.
3. Chennai - Alappuzha Express can be extended to TVC which will reach TVC around afternoon. This can be made to return as TVC - MAS SF Express @ 5:00PM. A daily train to Chennai via Alappuzha.
4. Chennai - Trivandrum SF Express which reaches Trivandrum around 7:30 can return as Alappuzha - Chennai SF Express around 1:10 pm. It can overtake Island Express at or before Kollam JN to reach ALLP around 3:30 pm.
Just like Guruvayur InterCity and Tiruchirappalli InterCity atleast TVC can free one rake as the rake of Vanchinad Express will leave as Executive Express so for nearly 4 hrs till Executive Express arrives one rake space is saved.