The county council is backing the HS2 high speed rail link despite acknowledging that it could lead to journey times to London getting longer.
The council has been criticised for backing the scheme, which will cross the south of the county.
It says it will improve services for Northampton rail travellers, while making them worse for people from Kettering, Wellingborough and Corby.
The county council says HS2 would cause a “significant disbenefit” to the north of the county if a new East Midlands station is built at Toton.
A KPMG report previously revealed the north of the county could lose £200m in economic output.
A report to be discussed at the council’s cabinet meeting on Tuesday says all journey times to Derby and Nottingham from Kettering, Wellingborough and Corby would increase.
It adds: “Providing competitive journey times and choice will be crucial to securing the economic vitality of north Northamptonshire and is vital in encouraging people to use public transport.”
The council has repeated its support for HS2 in its response to a Government consultation.
In the report, director of environment, development and transport Tony Ciaburro said: “Despite the impact of the route on parts of the county, we support the proposals on the basis of the supposed benefits that we will receive from released capacity on the West Coast Main Line and Midland Main Line.”