In August I was invited to speak to the East London Line project team about the original construction of the East London Railway.
The line is being extended north, using abandoned sections of the North London Line to Dalston, and improving connections south of the river to Crystal Palace and West Croydon, ultimately to include a branch to Clapham Junction.
The line is best known as containing Marc Brunel's Thames Tunnel. Inevitably much of what I said related to the construction of that tunnel, but there is much of constructional interest in the remainder of the line, particularly the section north between Wapping and Whitechapel, where the difculties faced were considerable.
The East London Railway got its Act in 1865 with John Hawkshaw was the lead engineer. The East London Line rst opened for traffic on 7 December 1869, but it was not until 1872 that work northwards started under Hawkshaw, with Thomas Walker as the contractor.
The work took nearly 12 months and was carried out in 4ft 6in lengths, 6ft wide, in Portland cement concrete, except for the section 2ft below the footings, which were in brickwork. On average, 3,000 gallons of water were pumped out every minute.
Generally the tunnel was built in open excavation and built in brick as a single way.
The greatest difficulty was experienced in London Docks, and there the tunnel was built with two independent ways.
The dock company obviously wanted to keep the dock open, and so work was done in two phases with the work carried out within cofferdam approximately 300ft long, of timber with puddle cores 8ft 6in thick.
The first phase took 22 months due to problems with the water-bearing strata. The second phase was faster. In that case the ground below the dock was dredged and replaced by clay into which the cofferdam piles were driven, providing a much more watertight foundation. Excavation was divided into four sections sub-divided into ve lengths of around 5m.
The ground below was a mix of clay with pockets of running sand and by excavating in small parcels, and rapidly placing the brick construction proceeded.
Beyond the dock the warehouses on the north side had to be underpinned. Concrete columns were carried down in excavated shafts beneath the foundation piers of the groined warehouse arches to rail level, a depth of 55ft below the warehouse oor. The work took seven weeks.
North of the warehouses the tunnel was driven, the only section on the line, terminating near Shadwell Station while again underpinning was necessary beneath the Blackwall Railway Viaduct.
On from there to Whitechapel the railway passed through deep cuttings braced with iron struts, and cut and cover construction. The line was nally opened through to Liverpool Street on 10 April 1876.
It is interesting to compare the East London connections at their peak in the 1930s with those proposed today. It is only when phase 2 of the work is completed, with the links to Clapham and the North London Line, that the vision of the 1860s railway engineers to use Brunel's Tunnel to facilitate travel between north and south London, will once more be realised.