Lambeth Suspension Bridge
Lambeth Suspension Bridge crossed the River Thames. It was 828 feet long, with three spans of 268 ft. Designed by Peter William Barlow, constructed by Porter and Co and opened as a toll bridge in 1862.
It had a solid-looking appearance, by the standards of suspension bridges, reflecting the designer's determination to provide a relatively stiff structure. Despite this, by 1910 its condition had deteriorated and it was restricted to pedestrians. It was demolished and replaced by the present bridge, constructed 1929-32.
Suspension was by iron wire cables made by R. S. Newall and Co. Each hanger had twin vertical rods, stiffened laterally by diagonal bracing. X-bracing was installed between hangers. The decks had massive longitudinal wrought iron box girders beams, with wrought iron cross beams topped by 3/8" iton plates.
The piers in the river were made of hollow brickwork cylinders within cast iron cylinders. Embedded in the top were the towers, assembled from wrought iron plates. These were fabricated in J. H. Porter's works in Staffordshire and each was shipped in one piece, and lifted from the barge onto its baseplate on the pier.
In August 1862 The Engineer stated that 'It is confidently expected that the bridge will be finished in about two months; if so, this will be not only the cheapest bridge over the Thames, but also the most expeditious piece of bridge building on record, taking into consideration its magnitude and span.' In 1893 they wrote that it was the ugliest bridge anywhere. Elegant it wasn't, but we would not now regard the Victorians as arbiters of good taste, noting the widespread dislike of unornamented surfaces!
'In 1879, when it was taken over by the Metropolitan Board of Works, its condition was so far from satisfactory, the cables and girders having suffered greatly from rusting. As much as 16 lb. of rust are stated to have been removed from a piece of cable 5ft. long.'[1]
Strengthening work was carried out in 1887.
1893 From The Engineer 1893/04/14: 'An examination of Lambeth
Bridge points out that while the superstructure of the river
piers - that is, the hideous wrought iron casings which form
the towers - retain their upright position, and the central span
itself its original lines, the side spans and towers may not. As
the shore casings or towers, as well as those in the stream, are
built with a strong batter or rake in the line of the axis of the
bridge, it is not easy without an accurate survey to discover
whether or not the former havve deflected from the plumb.
Fortunately, however, for the purpose, there is in each shore
tower a small door facing towards the roadway, and
vis-a-vis to the other. The jambs of these doors which
wore originally upright, appear now to be out of the
perpendicular, and the whole four doorways to be
canted over towards the river. It may be fairly inferred
from this lateral distortion, that the shore towers have
yielded slightly also in that direction. In other words,
the land cables and bars have not hold their own and
the bridge, in nautical parlance, has "dragged its anchors."
Following out our argument, the inevitable result of this
yielding of the mooring girders to which the anchoring down appliances are attached, should be the lowering of the
suspension cables of the side or shore spans. This is exactly
what seems to have taken place, as is readily ascertained by
carefully observing the bend, or more properly "kink," which
is plainly perceptible in the handrail on each side of both the
shore spans.
To return for the moment to the lowering of the
shore cables, which are twenty-eight in number, and composed of twisted wire. These cables support, by means of
vertical tension framing, braced diagonally together, the longitudinal or road girders, which are therefore constituted,
by virtue of this method, real continuous girders of many
spans. Considering the comparatively numerous and very
short intervals at which these supporting frames occur, combined with the stiffness of the road girder itself, one would
not expect any of the theoretical characteristics of the principle of continuity to become practically apparent. The
irregular wavy line assumed by the soffit of the shore spans is
evidently not due to this cause, but to the abnormal deflection
of the road girder itself, due to the sagging of the shore cables.
It should be mentioned that the footways are carried on
small cantilever beams attached to the main longitudinal
girders, and consequently they participate in all the movements and positions of the latter. The condition of tho handrail and parapet indicate unmistakably the effect of the
general deflection alluded to. At the points where the
"kink" occurs, which is not at the centre or lowest part of
the cables, but a short distance further towards the river
towers, the closely set thin trellis bars composing the railing,
or parapet, are not merely puckered, but bulged, buckled, and
in one instance, broken to an extent which plainly shows the
effect of the disturbing forces which have been at work. It is
quite possible that the unusual arrangement of the diagonally
braced framing is not well adapted to the suspension principle, and that, in this respect, the design is inferior to other
examples.
It cannot be denied that the very essence,
the raison d'etre of a suspension bridge, is mobility and
flexibility. A stiffened suspension bridge, in the proper sense
of the term, never has and never will be constructed. Had
the same causes been at work with regard to the shore spans
of Chelsea suspension bridge, the ornamental bosses and
stays for supporting the railing, which are of cast iron, would
in all probability have been broken in pieces. It is, however,
fair to add that the shore or side spans of Lambeth Bridge
are what may be termed "whole" instead of "half" spans,
and considerably longer, and consequently heavier than
those of the other similarly constructed bridges. It is not, however, necessary for a suspension bridge to
have any "whole spans." There is a footbridge over
tho Moldau at Prague, with a single pier in the centre
of tho river, and two side "half" spans of 305ft. each,
reaching to the respective shore. It has also been stated
on good authority that although the greatest care was
taken during the construction of the Thames Embankment to prevent any subsidence in the abutment on the
Lambeth side, a slight settlement did take place. Whether
this would affect the side span on the other side would
depend upon the behaviour of tho contra one. It would
thus appear that the older bridge may honourably retire
with the proud consciousness of having faithfully performed its duty as long as it could, and only at last yielded to
tho irresistible progress of events, and the inevitable tempus edax rerum. Tho younger structure, on the other hand, has
become proematurely unserviceable owing to causes which, if
not arising from defects inherent in itself, have failed to affect
the stability of other examples of the same type of construction in the upper roaches of the same river.'
1904 '... as long ago as 1887 Sir Benjamin Baker reported that an examination of the drawings alone was sufficient to warn an expert that it had not been designed by an experienced engineer. Sir Benjamin discovered a number of defects, including a movement of the Westminster abutment and a fracture in one of the anchorages. Temporary repairs were were carried out at a cost of £2984. Recently portions of the bridge have been opened up, and the result has been to show that the condition of the ironwork is dangerous, and it has in places been seriously eaten into by rust. Such precautions as could be taken by means of scraping and tarring have been ordered, but these are only regarded by the Committee as temporary expedients. There is, apparently, no doubt whatever that the bridge is dangerous, and should be at once replaced. .....'[2]
1903 and 1904 the reconstruction of Lambeth Bridge was again proposed, but on both occasions nothing was done.[3]
1905 it was necessary to restrict vehicle crosing the bridge to 2.5 tons in weight, and to walking speed
1910 in the interest of public safety, the bridge was closed to vehicular traffic.
1912 'In 1905 - that is to say, no less than thirteen years after the bridge was considered to be in such a dangerous state that its reconstruction was immediately necessary - the weight of any vehicle using the bridge was restricted to 2 1/2 tons, and all vehicular traffic had to proceed at a walking pace. Finally, in June, 1910, the bridge was actually closed to vehicular traffic.'[4]
1923 After unsuccessful attempts to gain parliamentary power to rebuild, a third proposal was made that Parliament should be asked to sanction the construction of a steel arch bridge, 60ft. wide, estimated to cost, exclusive of extensive and expensive approach works, £600,000.[5]
1929 Demolition began
1932 The new bridge was formally opened
This 1928 photograph shows a distinct sag in the nearest ('shore') deck. The Engineer in 1892 ascribed this to movement of the land abutment.[6]
Photo of the bridge being demolished in 1929 here. Another demolition photo here shows the bundles of suspension cables. The wires have a relatively high degree of twist.