document: Arriva Trains Wales faced criticism over "unacceptable" queues at central station during the Rugby World Cup.
  The firm wants to iron out issues before 74,000 people attend the Champions League final at the Principality Stadium in May 2017.
  Trials for the truck stunt event include Queen Street station opening.
  Usually it is closed after big events, with all people attending rugby and football matches and pop concerts using Cardiff Central only.
  But assembly members called for urgent change after people were left waiting for hours in long queues, most notably during the 2015 Rugby World Cup.
  To reduce waits, Queen Street will be open on Saturday for all people using Valley Lines services.
  People travelling to Bridgend and further west will use the rear of central, while those going to Newport, Ebbw Vale, north Wales, London, Bristol, Crewe, Gloucester and Birmingham will use the front.
  Bus replacement services will be used to take people to Pontyclun, Llanharan and Pencoed.
  Ongoing work on the Central Square development directly in front of the main station had made the need for changes more pressing.
  "As always we will be working to ensure passengers can get on trains as quickly and safely as possible," said Arriva's customer services director Lynne Milligan.
summary: Plans to avert big event travel chaos in Cardiff will be trialled as 30,000 people head to the city for Saturday's Monster Jam event.