You will have to take the Gemas to JB Sentral Shuttle Train service for all stations south, as currently the new Dual Electrified Railway Tracks that can carry the new fast ETS Trains is still under construction between Gemas and Johor Bahru.
If you want to continue your journey from JB to Singapore by train, you also have to take a Shuttle Train service.
These trains take just five minutes to cross the Causeway to Woodlands Railway Station and cost 5 RM per ticket to Singapore.
Trains from JB Sentral to Woodlands leave at :
05:30, 06:00, 06:30, 07:00, 08:30, 09:00, 11:00, 12:30, 15:30, 17:00, 19:00, 21:00 and 22:15.
These Shuttle trains to Singapore are always full in the early morning as they are used by workers to commute to Singapore, so you will have to book a seat well in advance if you want to use them.
Train tickets to JB Sentral from Gemas cost :
Shuttle Train (ST) Adults = 21 RM / Children = 15 RM.
Train 27 is the Intercity Express from Tumpat to Johor Bahru and costs :
Adults 27 RM / 33 RM (Upper or Lower) / Children 21 RM / 27 RM (Upper or Lower)
Like all trains in Malaysia it is best to book your seats as far in advance as possible.
You can do that at any KTMB ticket counter at any station or you can simply book online.
Tickets are available to purchase usually 60 days in advance.