TUNNELING is underway at Heathrow Airport as part of a new baggage system and only narrowly missed the Picadilly Line.
A 1.8 kilometre tunnel underneath the airfield is being dug which will connect Terminals three and five, eventually linking into the existing baggage tunnel network at a building which is to be cosntructed.
The tunnel boring machine (TBM) is undertaking the challenging excavation and is boring at a rate of 15 metres a day.
Dr Chris Millard, BAA's baggage and flight connections project director, said: "This is a highly complex and challenging tunneling operation that requires absolute precision.
"The TBM recently bored within metres of the LU Picadilly Line, careful planning and real-time monitoring of the rail track was undertaken throughout, however ground movement was negligible and the Picadilly Line service was not affected.
"I am delighted with the team's progress.
The tunnel is at the heart of BAA's £900million baggage improvement plans, and it is expected to be finished by July.
The tunnel passes over two rail lines, the Heathrow Express and Picadilly Line.