Thursday 14 November 2019

Greenwich Foot Tunnel centenary


By Myles Dove

As forecast in the May issue of GIH there was a celebration on Sunday 4 August 2002 to mark the completion of the Greenwich Foot Tunnel exactly one hundred years earlier. It was designed for the London County Council by Sir Alexander Binnie who had been responsible for the much longer Blackwall Tunnel, completed in 1897.  Like the foot tunnel it is still in use and celebrated its centenary five years ago.  When Greenwich Foot Tunnel was first completed, access was only by stairway for the lifts were not in operation till January 1904.  In that year 4 million people used the foot tunnel, increasing to over 6 million by 1915.  Now, with the Docklands Light Railway extended to Lewisham, there is another way to cross under the river but many walkers still use the foot tunnel and, of course, most cyclists have to use it because only fold-up cycles can be taken in the DLR. On the SUSTRANS national network of cycle routes the Greenwich foot tunnel is on route 1 linking Dover with Inverness so it is especially important for cyclists that this historic landmark is kept open and the two lifts kept working - even if they have to walk through it because cycling in it is forbidden

The idea for the foot tunnel centenary came from Greenwich Cyclists, whose co-ordinator, Barry Mason, first contacted the two London boroughs sharing the operating costs for the tunnel - Greenwich and Tower Hamlets - and the day began with an address by the Mayor of each borough in the open air near the south entrance. They were followed by an entertaining and informative talk by Chris Binnie, in tall hat and gear that might have been worn by his great-grandfather who designed the tunnel and whose name lives on in the title of the present-day consulting engineers, Binnie, Black & Veatch. It was with their support that the centenary event was staged and they have a wide-ranging practice with projects in the Americas and Australasia as well as in Europe.  Some of these were on view when the event transferred from rainswept Cutty Sark Gardens to the upper level of Queen Anne's Court in the University of Greenwich, by the river.

Here, the innovative techniques used in the first Blackwall Tunnel and in Greenwich Foot Tunnel were explained by Chris Binnie, who has retired from practice as a water engineer but is still actively involved as chairman of a committee for improving water quality in the River Thames.
In both tunnels the technical problems of driving a horizontal shaft through mixed water-bearing strata had to be overcame by using compressed air to restrain water penetration and in addition this was partially slowed by a temporary sealing layer of clay on the river-bed.   Construction of the foot-tunnel started with the sinking of a shaft on the north bank (known then as Poplar now Tower Hamlets) and as work went on compartments were fitted to keep up air pressure in work areas while allowing for separate movements of men and materials through the air locks.  Eight-hour shifts were worked with 45 minute breaks in vacating the workings so as to avoid compression sickness.  For most of the way the tunnel dig advanced 10 feet every working day decreasing to 5 ft. per day when they struck a layer of "open ballast" (pebbles near the Greenwich end.  As recorded by the LGC the foot tunnel is 1217 ft in length external diameter 12'9", internal 11'0" and it was formed with cast-iron segments bolted together, lined with concrete and faced with white glazed tiles.  The top of the tunnel is 55 ft below low water level and there are 88 steps at the northern end on the Isle of Dogs and 100 steps at the Greenwich end.  In the early years operating times for the lifts were from 5 am to 11 pm.  Currently they are 7 am – 1 on Sunday Monday - Saturday and 10 am - 5. 50 pm in the Greenwich foot tunnel (different time apply in the Woolwich foot tunnel-l' Both Greenwich and Woolwich foot tunnels are open all day and night with access by stairways when the lifts are not being opera!

However it is more restful to enter the  brick-clad and glass-domed enclosure (Grade I on the Statutory List of Buildings of Special Architectural or Historic Interest)  in Cutty Sark Gardens, listen for the whirr of winding gear and go in a spacious timber panelled lift, instead of struggling down or up stairways with bike or buggy. Timing was a critical factor when Greenwich Cyclists ended the event with a circular ride via Woolwich and the Royal Docks, returning through the Isle of Dogs to reach the Greenwich Foot Tunnel and sing out a birthday greeting before the lifts stopped working at 5. 50 pm.

In Greenwich Local History Library at Woodlands, comparative tunnelling methods are described in a paper read at the Institution of Civil Engineers in 1902 - see: ICE minutes for 25 March 1902 pp 1-24, from which these illustrations of the Greenwich Foot Tunnel are reproduced with due acknowledgement of library staff assistance. The location plan has the original layout of the riverside, with a Ship Tavern where later the Cutty Sark was brought to rest and on the north side of the river, the Great Eastern railway lines and sheds can be seen by the footway leading to the tunnel entrance; one of the vertical sections through the shaft shows the separate tubes and air-locks for men and material

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