Fly Past: Tunnel connected the old and the new...

Sep 9 2008 By Barry Dix

Heathrow

Passengers peering anxiously from the cabin windows of planes setting off from London Airport in its early years had little time to ponder the journey that lay before them.

Hardly had they settled in their seats, fastened their seatbelts and got stuck in to the barley sugars than they were off, hurtling along the runway and watching the ground slip away below.

For the crew it was all so simple. No taxi-ing to the other end of the airport and jostling for position with countless other aircraft.

They started the engines, went through the pre-flight rituals, got clearance to take off, trundled out the short distance to the end of runway one - and went.

But all that was to end when work got under way to build the new central area in the early 1950s.

Committed to constructing the buildings in the middle of the pattern of runways, the Ministry of Aviation and the Civil Aviation Authority set about arranging the construction of a tunnel to link the airport's new heart with the A4 Bath Road.        

It all seemed straightforward - just bore a huge great hole under the northern runway - until it was realised that the gravel subsoil was hardly suitable for conventional tunnelling at such a shallow depth.

The solution was a 'cut and cover' process involving the digging of a massive trench 30ft deep, 86ft wide and about half a mile in length, straight across the main northern runway.

It was a drastic measure and one that meant all planes had to land and take off from the southern runway - quite a trek from the Northside, from where all flights operated at that time.

Within the muddy confines of the gaping trench, a rectangular reinforced concrete 'shell' was created, divided into sections to provide two dual-lane carriageways with separate cycle tracks and pedestrian access either side.

Yes, people actually cycled and walked to the airport in those days!

Here's a fascinating picture, taken in early 1952, as the tunnel's innards were nearing completion. Massive cranes, working from specially-installed railway-style tracks had enabled the project to proceed at a good pace.

When the shell was complete, the gravel removed during the digging of the trench was compacted down around it and the runway restored.

Taylor Woodrow, the contractors, were delighted with the success of the project. A brochure from the time eulogised: "The tunnel at London Airport is the smooth, mysterious link between the old world and the new.

"Beyond the tunnel, like a diamond set in a paste of emeralds, lies the streamlined capital of Britain's airways - precise, brilliant, compact.

"This is London Airport Central. One of the major visible tokens of the resilience of 20th Century Elizabethan Britain.

"To the non-stop drama of the airport, the tunnel is the curtain raiser... ingeniously ventilated and subtly lit, the tunnel is itself a monument to British engineering."

Unfortunately, by the end of 1968, the size and weight of the aircraft operating above meant the roof of the tunnel developed faults which necessitated round-the-clock repair work, during which each bore of the tunnel had to be closed in turn.

The traffic chaos that resulted prompted the opening to traffic of the newly-finished cargo tunnel, not originally intended for public use.

The task of strengthening and relining the passenger tunnel was to take another four-and-a-half years.

A photo appeared in the now-defunct Sphere magazine. In one of the great understatements of all time, part of the text accompanying the picture reads: "London Airport is still, and will continue to be for some years, the scene of great building activity."

If only they had known!

Fly Past

Aug 8 2008

View