Changi Access Between Terminals - Lounges
 

Hello, my Cathay Pacific flight is departing Singapore Changi Airport from Terminal 4. I'd like to go to Terminal 1 to access the lounges there before my flight. I have OneWorld Emerald status. I know there is a train/bus, but is it possible for me from a security standpoint to do this?

Looked at the SIN airport web site? https://www.changiairport.com/
Will the T1 lounge be open at the time?
https://www.oneworld.com/airport-lounges?location=SIN

Edit
https://www.changiairport.com/en/air...and-jewel.html