Excavation of a new baggage tunnel at Heathrow airport is half way through using a Dosco roadheader boom.

The 1.8km long tunnel is the key element in airport owner BAA’s US$1.35bn baggage improvement plans for the terminals, and will form a key link between Terminal 3 and 5.

The budget for the entire fitted out tunnel is US$390M.

Contractor Ferrovial Agroman, which is part of the Ferrovial group that owns BAA, is boring the tunnel through London Clay.

The 5.51m diameter TBM was launched in mid-February and is due to complete the drive by July.

The tunnel alignment runs on average at a depth of 14m, passing close to fuel lines and rail lines, including the Heathrow Express.

Most recently, it passed within a few metres of the Piccadilly Line. Below the airfield it will reach depths of 35m.

The roadheader boom – ‘Beatrice’ – is fitted with a hydraulically-operated flipper plate to help loading. The TBM cost US$5M, said BAA.

The 5.1m i.d. precast concrete lining comprises 1m long expanded rings formed of eight segments.

By 2012, following other technological improvements at the others terminals, BAA wants the automated baggage system to be handling 110M bags per year.

Excavation at Heathrow airport for a tunnel that will be key to upgrading the baggage system