After two years of judicial investigation, only one person — the train’s driver — has been charged over the crash on the outskirts of the pilgrimage city of Santiago de Compostela on July 24, 2013.
The Alvia-type train tore off the tracks and ploughed into a siding while hurtling round a bend at 179 kilometres per hour (110 mph) — more than twice the speed limit for that stretch of track.
As Spain mourned its worst rail disaster since 1944, courts in the northwestern Galicia region launched an investigation amid allegations of faults in the railway's automatic speed-control systems.
The driver, Francisco Jose Garzon Amo, faces 79 counts of reckless homicide over the accident.
An association representing victims of the accident puts the full death toll at 81.
The courts have questioned various officials from the state railway company Adif but have dropped charges against all of them.
Dozens of protesters rallied on Friday on the square in front of Santiago de Compostela's grand cathedral — a destination for Roman Catholic pilgrims from around the world.
The association behind the rally said in an online statement that victims had suffered “humiliation and deceit” by the government and authorities which they said were “causing them even more pain”.
“They are trying to bury the truth,” said Arturo Dominguez, a spokesman for the victims' association.
“This was a foreseeable accident, so the driver is not the only one guilty,” he told reporters.
The protesters demanded a parliamentary commission be set up to investigate the causes of the crash.
The association in an online statement said victims had suffered “humiliation and deceit” by the government and authorities which they said was “causing them even more pain”.
A judge has brought charges against the driver Garzon but is still investigating the case and has yet to rule on whether he will face trial.
“Tommy forever. I will never forget you, my son,” wrote Tomas Lopez, who lost his 21-year-old son Tomas in the crash, on his Facebook page on Friday.
“On a day like this, a big hug to you and all the victims of the Alvia tragedy.”