The road bridge, operated by Atlantia's motorway unit Autostrade per l'Italia, collapsed in the port city of Genoa on Aug. 14, 2018, killing 43 people and laying bare the dire state of Italy's crumbling infrastructure.
Prosecutors have also asked for Autostrade and engineering unit SPEA to be sent for trial. The 59 defendants include former SPEA boss Antonino Galatà and former transport ministry officials, the sources said.
Autostrade and SPEA declined to comment. The ministry and lawyers representing Castellucci and Galatà did not respond to requests for comment.
The court will now set a date for the start of preliminary hearings, at the end of which a judge will decide whether to accept the prosecutors' request.
Managers at Autostrade and SPEA allegedly did not properly check the state of the bridge and did not correct serious issues that started to emerge only a few years after the viaduct opened in 1967, according to a document on the prosecutors' findings seen by Reuters.
Prosecutors claim the lack of maintenance was aimed at saving money and ensuring profits for the companies' shareholders.
The charges brought against the defendants include homicide, forgery and malicious omission of precautions to prevent disasters. The criminal code provides for a maximum sentence of 15 years.
Castellucci, who was behind Atlantia's international expansion, was ousted from the group in late 2019 after 13 years at its helm.
Under Italian law, firms can be held responsible for their employees' actions. Convictions for the companies could lead to fines and increase risks over legal claims in civil courts.
The prosecutors have decided to exclude from the trial request 10 suspects, on which further assessments and investigations will be carried out, the sources said.
Atlantia, which is controlled by the Benetton family, earlier this month agreed to sell its 88% stake in Autostrade to Italian state lender CDP to end a dispute with the government sparked by the 2018 disaster.
Autostrade, which also counts German insurer Allianz among its investors, runs half of Italy's 6,000 km (3,730 miles) of toll roads.
Three other investigations into allegations of falsified road safety reports, improper installation of anti-noise barriers and poor upkeep of road tunnels on Autostrade's network will be wrapped up by the end of the summer, the sources said.
(Reporting by Emilio Parodi and Francesca LandiniEditing by Mark Potter)
By Emilio Parodi and Francesca Landini