Network Rail said it does expect the Cambrian line to open for normal services from Monday.
It comes after one man died, and 15 other people were injured when two trains crashed near to Llanbrynmair in Mid Wales on Monday evening. The man who died was Tudor Evans, who was 66 and from Aberystwyth.
Network Rail said the investigation teams have now finished their site-based investigation.
That has allowed Transport for Wales (TfW) engineers to get onto the scene of the crash and separate the two damaged trains, which are in the process of being removed from the site.
At the same time Network Rail engineers have been carrying out repairs, maintenance and a series of checks and safety inspections.
A statement from Network Rail sought to reassure the public over the line, saying: “Safety systems on the trains that use the line continue to be regularly checked and inspected.
“Test trains will run through the area to make sure everything is operating normally before beginning passenger operations on Monday.”
But, it said, the incident may still affect train services in the short term and passengers should continue to check before they travel.
Nick Millington, Network Rail’s Wales & Borders route director said: “Monday night’s tragic events will forever be etched in my memory and my thoughts remain with all those affected.
“Thankfully, incidents like this are extremely rare on the railway network. We continue to operate one of the safest railway networks in Europe.
“Our engineers have been on site throughout and have conducted very thorough safety checks and we will run test trains through the area.
“I am grateful to the local community who have been very accommodating throughout this last week while we have been managing this incident.
“I would also like to thank passengers for their patience, understanding and support during the last few days as our teams have worked tirelessly to restore the railway as quickly as they could.”
Jan Chaudhry van der Velde, chief operating officer for TfW, said: “The railways in Wales have a very good safety record, so when serious incidents like this happen, we at TfW, together with our partners at Network Rail, are determined to get to the bottom of what caused it.
“For that reason, we are co-operating fully with the authorities investigating the collision, and in particular, the Rail Accident Investigation Branch.
“We have worked hard to clear the trains safely from the accident site, and to carry out full safety checks and tests before reopening the line for passenger trains.
“Our condolences go to the family of the passenger who passed away, and we hope that those passengers and staff members injured in the collision make a speedy recovery.”
Network Rail said that due to “operational challenges” following the incident, there will be no TfW services running between Shrewsbury and Birmingham International this Saturday or Sunday.
It confirmed that ticket acceptance has been agreed with West Midlands Railways on the route, but added that people are advised to use alternate routes where possible.
