It is hoped a brand new motor vehicle testing facility will boost high-tech engineering in a county famous for the Silverstone race track.
Catesby tunnel near Daventry in Northamptonshire was left abandoned and flooded for decades after trains stopped running through it but has recently been refurbished.
Car makers from around the world are interested in testing vehicles by driving them at speed through the 2.7km (1.7 mile) facility to assess things such as aerodynamics and performance.
Rob Lewis from Catesby Projects said: “This is a controlled track where the conditions are the same every time.”