No getting out of minecarts

I have searched and searched for 2 days now, i cant seem to find a plugin that will do the following;
Stop players from getting out of mine carts..
permissions for admins
and support for 1.8 not the 1.7 and 1.8 but the completely 1.8
in fact i haven't even found a plugin that does any of this..
it would be great if someone could make this for me...
i need it for a theme-park server i am currently creating
so no one can hop out of the minecart and push the cart backwards
Which has Happens every time someone "Accidentally" presses shift,
i dont need this straight away but i do need it before 2016
as my server is still under construction

 

Thanks!
i do use traincarts to add stations ECT
but what is the command to put on the sign @timtower

 

Thanks so much!
i appreciate it