Mr Evans, from Capel Dewi, Ceredigion, died after the crash and four others were seriously injured.
A further 11 people sustained injuries which required hospital treatment
On Tuesday, the RAIB issued an update on the investigation, adding that an automated system that helps train wheels grip tracks failed.
It said initial analysis indicated the 1J25 service from Shrewsbury to Aberystwyth was travelling between 15mph (24 km/h) and 24mph (39 km/h).
The 1S71service from Machynlleth to Shrewsbury was travelling at about 6mph (10 km/h) in the opposite direction.
The RAIB is continuing to analyse evidence relating to the collision speed, which it said remained an area of ongoing investigation.
Investigators said neither train derailed in the collision, although significant damage was caused to the leading vehicles of both trains.
