Ian Ritchie Architects

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The Ventilation Towers of the Second Blackwall Tunnel

January 1996 © Ian Ritchie

In the East End of London, on each bank of the Thames, curvilinear sculptures stretch upwards towards the sky. Forsooth, what manner of construct is this that stands so proud and independent of its visible surroundings? From the river, to the trained eye, these white almost surreal objects can be seen simultaneously. What are they? They are very expressive, powerful and confident. Why? Their purpose seems to defy immediate explanation. The have ambivalence. They appear alien, but beautiful, disturbing yet peaceful. Their incongruous appearance in the superficial urban wasteland that surrounds them suggests that both landscape and object result from another era.

Focussing not only one’s eyes but also one’s mind on them, their unmistakable form invokes air, perhaps even more so than funnels of great ships which frequented these waters until the late 60’s. There is a clue in the air. Engineering intervention beneath the ground in this part of London has existed since 1889.

The very first road tunnel excavated underneath the Thames is the original Blackwall tunnel.
It was designed by Lord Cowdray, (who had recently completed the Hudson Tunnel in New York), and was built between 1889 and 1897. Two generations later, in 1937, The London County Council decided to build a second road tunnel approximately 250m downstream of the existing tunnel. The LCC (Tunnel and Improvements) Act of 1938 authorised the duplication of the tunnel and the aquisition of land. What determined the alignment of the route of this tunnel? Was it determined in part by the availability of suitable sites to house the two caissons which would form the permanent ventilation shafts connecting, of necessity, the tunnel to the air above?

Yes, this is the explanation of their siting and raison d’être.
There is a group on each bank of the Thames 780 metres apart, one at the northern end just off Prestons Road and nearby the new Reuter’s HQ designed by Richard Rogers Partnership, and the other at the southern end on the Greenwich Peninsular.
Each twin assymetric tower ventilation buildings is composed of two funnels based upon two distinct elliptical plans tapering upwards, intersecting to form a valley before separating into funnels. They spread out below this valley to enclose four large circular fans and motors. The flow of their form was created using reinforced concrete shell construction, with their lower skirts”suspended” in a catenary profile. The lower intake funnel has a louvred collar, while the louvres of the much taller exhaust funnel are concealed – a touch of deception, or simply expedient to throw the disgusting fumes upwards into the air to fall, diluted, some hundreds of metres downwind.

Implementation of the tunnel and ventilation shafts was delayed, first, by the outbreak of the Second World War, and subsequently by the economic stringency which followed.
Work began on the northern approach road in April 1958, and tunnelling work in 1960. The tunnel was designed by the engineering firm of Mott Hay & Anderson and built by Balfour Beatty & Co. It was completed in May 1964 at a cost of £ 7 million, and officially opened by Desmond Plummer, Leader of the GLC,on August 2nd. Today, northbound traffic uses the original tunnel and the second tunnel serves southbound traffic.
The final mathematically expressed profiles of the shells – designed to be as thin as possible within the limits of corrosive attack – was developed by the specialist sub-contractor, The Cement Gun Company and their consultants Flint & Neil, and constructed under the supervision of William J Jerram.

Initailly, the concept design was undertaken, with the aid of a model, by the GLC’s Department of Architecture and Civic Design, under the direction of the GLC Chief Architect, Hubert Bennett, in a group led by Mr Haines. Apparently a young architect in the group was given the chance to design them- Terry Farrell, who left the GLC before the project was begun, and who went on to do quite different and eclectic architectures.

© Ian Ritchie 01/1996