Automatic Passport Control Channel Foreigners holding passports or travel documents issued by Visa Waiver Program of participating countries which falls under visa exemption with 30-day duration of stay such as Singapore and Hong Kong. Those who fulfilled the requirement can use Automatic Passport Control Channels located at the Eastern Inbound 
Passport Control (Zone 1), A3-A8 channel, Suvarnabhumi Airport.
Automatic Passport Control Channel's criteria and instruction for foreigners (Singaporean and Hong Kong) 
1. Criteria: must be foreigners holding passports or travel documents issued by Visa Waiver Program of participating countries which falls under visa exemption with 30-day duration of stay (Singaporeans and Hong Kong)
 2. Instructions
       1. Put your passport on the Automatic Passport Control Channel
       2. Scan your fingerprint
       3. Take a photo
       4. Wait for an approval from a staff (behind the Automatic Passport Control Channel)
*** Notes 
1 . Automatic Passport Control Channel's system has been improved and can now check information of aliens with electronic certificate and data from ICAO Public Key Directory in the first usage which is automatically registered to the system.
2 . In case of overstaying, the alien will not be eligible to use the Automatic Passport Control Channel.Therefore, the person must use the Passport Control  to pay a fine. 
3. Location : around the Eastern Inbound Passport Control (Zone 1), A7-A8 channel.

Reference: Immigration Division 2