624
Immigration and Checkpoints Authority spokeswoman Ngoon Pei Ling said during the trial period the scanners would be placed at bus checkpoints , where passengers are already required to disembark for immigration purposes .
 bus: vehicle; passengers: artifact; checkpoints: destination
Given event type and trigger, please tell me the arguments of all the listed option. Output format is "name1: role1; name2: role2". 
Event type: transport 
  Option: victim, artifact, destination, place, origin, vehicle, agent 
Text: {0} 
Answer:
 bus: vehicle; passengers: artifact; checkpoints: destination