OPTED-out Canon Slade School has been given the go-ahead by Bolton Council to build 14 new classrooms.
It will mean that the Church of England School can take on an extra 30 pupils from September 1998.
But the school has given guarantees to the council that it will encourage parents to send their children to school on buses, rather than in cars.
The school will also urge staff and sixth form pupils with vehicles to adopt a "car sharing" scheme.
Councillors were concerned that the proposals would increase traffic chaos on Bradshaw Brow at peak times.
But the school sent in a letter to planning control sub committee councillors saying: "We give you a firm assurance that the school will do everything possible to ensure that any traffic impact, as a result of the plans under discussion, is reduced to a minimum."
Planning permission was also given on condition that the school looked at providing an extra bus lane in its grounds.
Canon Slade is always popular with parents choosing their child's secondary school.
Last year, more than 400 children chased just 240 entrance places.
Another planning application to build a new sports hall and swimming pool at the school was also approved.
Converted for the new archive on 14 July 2000. Some images and formatting may have been lost in the conversion.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article