Brooklyn Bridge – Ink drawing (I may add colour at a later date)
Impressions of New York City
My previous post describes how we sailed round Manhattan past The Statue of Liberty. After this we passed under The Brooklyn Bridge where this scene is from. I have long been fascinated by this structure and have read much of its construction and, hence, its history. Designed by John Roebling and, after his death construction was carried out by his son, Washington. Washington was severely incapacitated by compression sickness – the “bends” – feared by divers, when he was supervising work on the river bed under the Manhattan abutment. It was left to his wife, Emily, to oversea the final stages of the bridge as Washington was too ill to even leave his sick bed.
This episode is where my interest began. Some of you will know that I stay near one of the world’s other iconic bridges – The Forth Bridge, which spans the Firth of Forth just west of Edinburgh. Some of the building techniques on this bridge were copied from the Roebling’s methods, one being the way the massive foundations were constructed. This involved sinking a sort of upside down box onto the river bed and driving the air out under pressure. Men would then dig the soil and rock away allowing the “box” to sink downwards until solid rock was reached. The whole thing was then filled with concrete so the upper works could be added later. It was this working under pressure in these “caissons” that caused much suffering as the dangers of sudden decompression were unknown, in fact the paralysing symptoms, which often were fatal, were known as “caissons disease”. In all 27 deaths were recorded during the bridge’s construction, some perhaps due to caissons disease. The Forth Bridge recorded more fatalities 98 – in all. Some of the men, working on the sea bed, were reluctant to come to the surface and worked very long hours before enduring the agony caused by changes in pressure.
During my teaching days I used to tell of the way such structures were built and the “Great East River Bridge” was always part of my narrative. Incidentally, the tower on the Brooklyn side sits on solid rock but the one on the Manhattan side does not. Because of the ever-increasing depth solid bedrock was never reached and the caisson sits on sandy soil, albeit under the huge weight of a larger tower. It is estimated, unfortunately, that a massive earthquake would cause liquefaction of the foundations and cause the structure to fail. Maybe some retro-fitting, such as that taking place on the Golden Gate Bridge is required – I’ve seen the Discovery Channel programme!