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Paddington LTVA Bridge Project
- Discovering Brunel
Javad Akhtar
Jo’ Kenward
Bal Chana
22 October 2004
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Isambard Kingdom Brunel – The Man
• 1806 – 1859
• Born in Portsmouth
• Son of Sir Marc Brunel
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Brunel – Career Snapshot
• 1826 – Thames Tunnel
• 1831 – Clifton Bridge
• 1833 – Engineer to Great Western Railway
• 1837 – PS Great Western Launched
• 1847 – Atmospheric railway opens Exeter - Teignmouth
• 1854 – Paddington New Station opens
• 1859 – Died aged 53. Chains from Hungerford Bridge
used on Clifton suspension bridge in his memory.
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• 1838-39 Paddington canal Bridge
• 1841-5 Hungerford pedestrian.
• 1846 Usk Viaduct Newport
• 1850-52 Wye Rail
• 1854-8 Royal Albert, Saltash
• 1864 Clifton Suspension
Brunel – Iron Bridges
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Paddington LTVA - London
• New Bridge over 15 rail
tracks and canal
• Replacement for existing
with increased capacity
• Hyder involvement since
1998
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Paddington LTVA – Options
• Bridge Closure
• Bridge Form
• Construction
methodology
• Procurement options
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Paddington Programme
• 1998 – 2000 Design options and strategy
• 2000 – 2001 Procurement and scheme development
• 2002 Advance Works, tendering & design
• 2003 Design and service diversions
• August 2003 start of main works not requiring closure
• Bridge Closure 11th January 2004
• Early January 2004 programme modified to accommodate
careful dismantling of Brunel Bridge
• Completion of main bridge replacement – spring 2006
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Layout of existing structures before work commences
1
SOUTH
ABUTMENT
BOWSTRING ARCH
PIER 10/11 LUL
NORTH
ABUT.MASONRY ARCHES CANAL
Stage
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1. Raise the existing bowstring arch bridge by
approximately 10m in to the air
2. Construct the support structures for the canal
bridge including a reinforced earth abutment and
piled foundations with concrete supports
5Stage
2
22
1
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1. Construct the rail bridge deck phase 2
2. Install a restraining system at the rear of the rail bridge to
stop the bridge from sliding forward when launched
10Stage
1
2
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Brunel Bridge
• Mid 2003-Construction programme planned to demolish existing
bridges along including Canal Bridge
• Dr.Steve Brindle from English Heritage researching material for
Paddington station uncovered Brunel’s note book, sketches for
canal bridge.
• Site visits revealed that the bridge Brunel referred to was the
Canal Bridge at Paddington.
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Brunel Bridge
• English Heritage commissioned trial pits to be dug on site in
August 2003 to verify the Brunel notes.
• Records show that it probably the first iron bridge built by Brunel.
• The bridge is a two span structure of 10.7m (35ft) and a side
span of 4.9m (16ft).
• The girders are of unusual x-section, lower flange a heavy bulb
tee, a thick web and a solid bulb for upper flange. Each 35ft
beam weighed 20 tons.
• The trial pits confirmed that the Canal Bridge was indeed the first
cast iron bridge designed and constructed by Brunel in 1838-39
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Brunel Bridge
• Unique design; use of cast iron possibly due to tight headroom
requirement and large span. Wrought iron has greater tensile
strength but may require deeper beams.
• Brick arch would have added too much height leading to a
steeper gradient to Harrow Road
• Brunel load tested 35’ beams to 20,25, & 30 tons; the 16’ girders
tested to 30 tons
• Items fitted like a jigsaw; no bolted connections; shaped ends
and wedges used to hold beams together.
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Brunel Bridge
• Load assessment carried out in august 1998. No drawings
available. Information obtained from trial pits and site surveys.
• Not withstanding the shallow arch shape, actual structural
behaviour was as simply supported beam.
• Load restriction imposed in 1999 as bridge assessed capable of
only 7.5 tonnes capacity.
• Brunel’s simple beam test results demonstrated a higher capacity
than the modern assessment. Exact details of the testing are not
known.