Work to repair and rebuild the railway has been taking place since December 2015, when the line had to be closed after it became severely damaged.
Engineers are working to build a new 235 metre-long viaduct, supported by 134 concrete columns. The work is ahead of schedule and Network Rail is working towards completing the project in the autumn.
Network Rail’s area director, Paul Rutter said: “We understand the impact of this closure has had on passengers, and our engineers have been working round the clock to finish the repairs and get trains running again between Dover and Folkestone.
“We had set aside time for interruptions to the project through bad weather and other issues which can occur on major projects, but so far that contingency has not proved necessary. As a result we are much further ahead than we had expected and have seen the overall cost of the project decrease.
“As soon as we have a firm date for reopening the railway line, we will let passengers know.”
Network Rail’s programme manager, Steve Kilby, said: “This project has been a challenging one and normally a scheme of this size would take two years to design and build. We are very proud of everyone’s commitment to get this line open as soon as possible.
“We would like to thank passengers and our neighbours for their patience while work has been carried out to rebuild the railway at Dover.”
Richard Dean, Southeastern’s Train Service’s Director, said the company was currently working hard on a developing a new timetable to account for the re-opening of the line over the Dover sea wall.
He added: "I know passengers have found it difficult since the partial collapse of the sea wall severed the track we run our trains on at Dover. I would like to thank them for their patience.
"We put in place replacement buses, shuttle train services and a comprehensive compensation package for season ticket holders as the damage to the wall meant we were unable to run a full service.
"It is very good news that Network Rail's engineers say they are confident the work will be finished in the autumn, much earlier than the December date originally predicted, as the earlier we can provide the full service our passengers need the better. Network Rail's engineers have worked around the clock and the progress made is remarkable."
MP for Dover and Deal Charlie Elphicke said: “"This is great news for Dover & Deal. The works are clearly ahead of schedule. Rail travellers and our whole community are set to benefit. I am looking forward to the line reopening and am incredibly optimistic that this date may now come sooner rather than later.
"Many congratulations to Network Rail and Costain on the incredible job they have done so far. This is a timely reminder of how great our nation is at large scale civil engineering works as we embark on the next stage of our national journey."