The cause of the crash was determined to be a human error on behalf of the driver of the train from Leuven, who passed a red signal without authorization.

Because of multiple difficulties the judicial investigation lasted for years, causing the train driver, the NMBS/SNCB, and Infrabel (the infrastructure operator) to be summoned to court only in June 2018.

The train from Leuven, an AM70 Class Classical EMU, was running south on schedule to Braine-le-Comte in the normal (left-handed) direction on its track.

[3] The train from Quiévrain, an AM54 Class Classical EMU, was running north in the normal direction on its track, ten minutes behind schedule.

Police, fire, and emergency medical services were involved in the rescue operations alongside the Red Cross and Civil Protection.

The more seriously injured were brought to a fire service tent until a field medical post was set up in front of Halle train station.

[2] Rescuers early on discounted the possibility of finding survivors still trapped in the trains, and the search for bodies was interrupted at nightfall to resume the next morning.

Recovered bodies were identified by the Belgian federal police's Disaster Victim Identification team and transported to the morgue at Neder-Over-Heembeek military hospital where support was provided for relatives of the dead.

[3] Further disruption was also caused on 16 February when train personnel staged an unofficial strike in protest of what they called "deteriorating working conditions", which they said could lead to crashes such as the one in Buizingen.

[3] After the recovery of human remains and the necessary investigative acts on the scene, which took two to three days, the (relatively) undamaged carriages were hauled away between Tuesday 16 and Wednesday 17 February.

On Monday 1 March, two weeks after the crash, the tracks and overhead wiring were repaired by Infrabel and all suspended train traffic could resume on the affected lines.

[20][21] On Saturday 12 February 2011, a year after the crash, a bilingual French-Dutch memorial stone was unveiled on the town square of Buizingen in remembrance of the 19 deceased victims.

[2] The CEO of the NMBS/SNCB at the time, Marc Descheemaecker [nl], replied that it was "too early to confirm a hypothesis" and that "[we] will have to carry out a neutral enquiry" but admitted that de Witte's comments were "not unbelievable".

A theory was suggested that these defects were caused by the electromagnetic field of high-speed trains rushing past the signal on adjacent tracks.

[25][26] The safety investigation carried out by the Belgian Investigation Body for Railway Accidents and Incidents (Organisme d'Enquête sur les Accidents et Incidents Ferroviaires in French; Onderzoeksorgaan voor Ongevallen en Incidenten op het Spoor in Dutch) after the crash established that the signal passed by the Leuven–Braine-le-Comte train was red.

Minister Vervotte wanted to track all measures regarding train safety taken since then, together with former NMBS/SNCB CEO and state secretary for Mobility at the time Etienne Schouppe (CD&V).

[28] In the Chamber of Representatives, the lower house of the Belgian Federal Parliament, opposition parties including Groen!, N-VA, Vlaams Belang, and Lijst Dedecker asked for a formal parliamentary investigative commission to research the circumstances of the crash and railway safety in general.

[32][33] In the report, the commission concluded that the general railway safety level in Belgium did not undergo any meaningful improvements from 1982 to 2010, unlike that in foreign countries and despite the deadly crashes in Aalter in 1982 and in Pécrot in 2001.

Favouring national companies in public tenders was made illegal in the European Union in 1993, but the Court of Audit said that recent safety investment projects regarding GSM-R and ETCS could have been done better nonetheless.

[31][34] The parliamentary report confirmed that, even when ETCS would be fully rolled out in the future, the human factor would remain very important in railway safety.

Procedures on how to handle the passing of a red signal need to focus less on the punishment of the train driver and more on how to avoid similar incidents in the future.

Nor was distraction, abnormal fatigue, time pressure, or stress found to be a plausible cause, aside from the fact that the driver had had a short night's sleep.

[3] The Belgian railway companies were already aware of the impossibility of eliminating human errors and of the need of technological solutions to combat red signals being passed for almost a decade.

As reasons for this, the Investigation Body mentioned the cultural heritage of the railway companies, which was characterised by a reactive attitude and a normative response to crashes focused on ground personnel.

However, because TBL 1+ does not provide complete monitoring of a train, the Investigation Body noted that this catch up could only serve as a transitional measure towards the implementation of ETCS by the two companies.

Due to the large number of people expected, the tribunal exceptionally held session in a nearby community cultural centre.

In the Belgian justice system, people who believe they have suffered damage as the result of a crime can become civil parties to the case and ask for compensation during the trial.

[40] The police tribunal refused the language change because granting so would pose a risk of exceeding the reasonable time and the statute of limitations (which would expire in 2021).

The president of the French-speaking tribunal of first instance of Brussels, Luc Hennart, stressed that the case would be prioritised so as to avoid the statute of limitations setting in.

They explained that on the day the television report was made (20 February 2010), the place had just been released by the investigating judge, after which Infrabel had recovery operations carried out that morning.