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.

The Clogher rider took a narrow victory over compatriot Alastair Seeley after 10 laps, with Dublin's Jack Kennedy fourth and David Allingham in sixth.
Seeley is unable to score championship points onhis Spirit Moto2 machine.
Farmer now lies second in the standings on 145 points, five behind Tarran Mackenzie, who has taken up Danny Kent's ride in the Moto2 MotoGP series.
Allingham is third on 134 points, followed by Carrickfergus rider Andrew Irwin on 115 and Kennedy with 100.
The feature Supersport event will take place on Sunday.
Be Wiser Ducati pilot Glenn Irwin misses the meeting through injuries sustained in a practice crash at Knockhill but Northern Ireland riders Michael Laverty, Andy Reid and Josh Elliott will take part in Sunday's two Superbike outings.
Reid has been called up to replace Davide Giugliano in the Tyco BMW team for the remainder of the season, while Elliott stands in for the injured Christian Iddon for this round.
Elliott is also set to take in this weekend's Superstock 1000cc races, along with MD Racing representative Carl Phillips.

Gwent Police was called to the incident near Raglan Services at about 11:30 BST on Sunday.
The ambulance service said a patient had been taken to Bristol Royal Infirmary.
The road was closed in both directions between Monmouth and Raglan for about four hours but police said traffic was now moving freely.

Researchers discovered it after looking back at some fossils found in the late 2000s in Morocco, North Africa.
Two of the fossils were in such good condition that the team were able to make this amazingly detailed reconstruction.
You can clearly see its small mouth filled with hundreds of teeth and the prickly spines which cover its body.
This slug like creature also had a built in, helmet like, shell to keep it safe from predators.
It might look a little terrifying but it was only four inches long and scientists think it survived by eating algae off rocks.
Molluscs first appeared on earth around 520 million years ago, Calvapilosa is an ancient relative of modern molluscs.
A mollusc is a type of animal that doesn't have a spine, there are lots of different kinds including slugs, snails, oysters and squid.
Jakob Vinther who was the lead researcher on the project said "This discovery brings a neat solution to how the ancestor of all molluscs may have looked."
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.
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Keith Farmer followed up his double at Knockhill by winning the Supersport sprint race at Snetterton on Saturday.
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A person has been taken to hospital by air ambulance following a serious crash on a major road in Monmouthshire.
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This is Calvapilosa, a prehistoric relative of modern sea slugs.