Rebuilt schools could be moved outside Belfast in an effort to reduce the number of pupils travelling into the city, it has been revealed.
More than 12,000 secondary pupils commuted into the area every day, most from the South Eastern Education Board, the Department of Education said.
With some ageing schools due to be replaced in the future, Education Minister John O'Dowd outlined the next steps for a shake-up aimed at making them more viable.
"I believe there is a growing realisation among everyone with an interest or involvement in education that change is needed and that it is happening," he said. "I hope that with the necessary leadership and belief in a future vision, we can make the necessary improvements for the benefit of all children."
The aim is to keep the journey times for pupils to below 40 minutes. Mr O'Dowd said 12,305 post-primary pupils attended schools in Belfast but lived outside the board area. Around 9,000 were from the South Eastern Board and 3,000 from the North Eastern.
Mr O`Dowd said: "We need to ask ourselves is this what we want for the future? Is it sustainable economically, educationally and environmentally?" He is to commission research to consider the issue.
"The pattern of provision in the corridor between the South Eastern and Belfast boards is an area where I believe more focused and detailed work is required," he said.
Education boards published plans for streamlining the provision of post-primary education on Tuesday - aimed at tackling 85,000 empty classroom seats and making schools more viable. At least two Belfast schools were recommended for closure.
The failing Orangefield High in the east is expected to shut from August, with pupils transferring to Ashfield Boys or Girls High. St Gemma's High in the north is also earmarked to end lessons.
The Catholic Council for Maintained Schools plans to reduce the number of Catholic institutions in Glengormley and north Belfast from seven to four or five.