Madrid (CNN) -- Spanish rail chiefs testified on safety before lawmakers Thursday, two weeks after 79 people died and scores were injured in a horrific derailment in northwestern Spain.
The investigation has focused on the actions of the train's driver, Francisco Jose Garzon, but questions have also been asked about the safety systems in place on Spain's national railway network.
Gonzalo Ferre Molto, president of state-owned rail infrastructure company Adif, and Julio Gomez-Pomar, president of state railroad company Renfe, outlined what is being done to ensure the safety of rail travelers.
"My desire is to know the whole truth and avoid the possibility of an event of this nature happening again," said Ferre. "This is the best service we can offer to the victims and the whole Spanish society."
Lawmakers heard that the route the train was on, from Madrid to Ferrol, includes a mix of conventional and high-speed track, with the latter allowing high-speed trains to travel at over 200 kilometers per hour (124 mph.)
Two different safety systems are used in Spain: the European Rail Traffic Management System for the high-speed track and another known as ASFA on conventional lines.
The train and its engineer were switching between the two kinds of track and operating system in the course of the journey.
A transition from an ERTMS-operated section to the other system happened about four miles before the train derailed on a curve near the northwestern city of Santiago de Compostela, Ferre said.
That section of track had been inspected on April 20, he said.
Speed limit on bend
Court officials have said the train was traveling at 153 kph (95 mph) when it derailed, nearly twice the speed limit on the curve where the accident happened.
After the accident, a temporary speed limit of 30 kph was imposed on the stretch where the accident occurred and is still in place, Ferre said. A permanent limit of 60 kph will come into force once that is lifted.
"Our safety department is developing an investigation report," Ferre told the parliamentarians. "Safety in the rail sector is an open subject."
Gomez-Pomar said Renfe has started to examine the safety systems in place and admitted that they can be improved.
He said the driver had taken control of the train at Ourense station at 8:06 p.m., about 35 minutes before the crash occurred. Garzon had started his working day about eight hours earlier, but his effective driving time at that point was less than three hours, he said.
The driver, who has worked for Renfe since 1992, had passed his most recent health test, Gomez-Pomar said. He had been qualified to travel the Ourense-Santiago stretch of track since February 2012 and was given permission to drive the kind of train involved in the crash last November.
In total, more than 7,000 trains have passed through the stretch where the accident occurred, Gomez-Pomar said.
Some lawmakers from smaller parliamentary groups criticized what they said was a rush to blame the driver for the crash.
"Shifting the responsibility of a high-speed train on to the machine operator is, from our point of view, a rather excessive responsibility," said Rosana Perez, of the Mixed Group.
She suggested the number of drivers aboard a train should be increased as a safety measure to protect against human error.
"It has been said that the only cause is the human factor. If it is really so, we are lost. This argument falls by its own weight," said Gaspar Llamazares, of the United Left group.
Investigations continue into the cause of the July 24 derailment, which shocked the nation.
As of Thursday, 38 people remain in the hospital, six of them -- all adults -- in critical condition, according to local health authorities. No nationalities were given for those still hospitalized.
Authorities have charged Garzon with 79 counts of homicide by professional recklessness and an undetermined number of counts of causing injury by professional recklessness. He has been given conditional release but has surrendered his passport.
Three witnesses were expected to give statements Thursday to a court in Galicia, in a closed-door session. They are a station manager and two neighbors who went to help the survivors immediately after the crash.
Minutes before the derailment, Garzon received a call on his work phone, apparently receiving instructions on the way to Ferrol from a Renfe staff member, a court in Galicia said last month.
The train was nearing the end of the six-hour trip between the capital and Ferrol at the time of the accident.
CNN's Laura Perez Maestro and Al Goodman reported from Madrid, and Laura Smith-Spark wrote in London.