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.
The East London Railway got its Act in 1865 with John Hawkshaw the lead engineer.
Financial problems checked progress northwards shortly afterwards. Meanwhile the connections to New Cross were built by a contracting consortium of Thomas Brassey, George Wythes and the Lucas Brothers.
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 1.4m lengths, 1.8m wide, in Portland cement concrete, except for the section 600mm below the footings, which were in brickwork. On average, 14,000 litres 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.
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 90m long, of timber with puddle cores 2.6m 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 five 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 17m below the warehouse floor. The work took seven weeks.
North of the warehouses the tunnel was driven, terminating near Shadwell Station. 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 sections of cut and cover construction.
The line was nally opened through to Liverpool Street on 10 April 1876. Its value as a way of connecting with other Underground routes was enhanced in the 1880s with a link to the newly extended Metropolitan Railway.
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 this work is completed, 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.