|Reinforced concrete contains steel rods or wires to provide
additional strength and particularly to improve performance in tension. It was
used extensively by the Southern Railway, principally for pre-fabricated
structures, including fences, platforms, huts and footbridges. These were all
constructed from relatively small components. The outdoor equipment at
substations built during the 1930s is carried on reinforced concrete frames.
Reinforced concrete road bridges are particularly found spanning lines in the London suburbs and coastal towns, because housing development between the wars required many new roads and widening of existing ones.
Reinforced concrete could be cast in situ, that is poured into shuttering in its final position. Alternatively, components could be pre-cast at special concrete works, such as that operated by the Southern Railway at Exmouth Junction. Manufacture at a concrete works made it easier to achieve high quality, but had the disadvantage of requiring transport of heavy components to the construction site. Offsetting that, pre-cast beams could be lifted into position quickly, which was often essential when undertaking work over roads and railways that could only be closed to traffic for short periods.
Many early concrete bridges contain quite substantial steel beams, to the extent that they are effectively steel bridges encased in concrete.
Southern Railway concrete over bridges are characterised by horizontal beams, sometimes supported on quite small triangular corbels cast as one with the beam. Abutments and parapets were normally cast in situ, but blockwork or brickwork was sometimes used. Jones Lane bridge, Hythe (above) spans the Fawley branch, which opened in 1925. Increased road traffic has resulted in the carriageway being extended to the full width of the bridge deck. Pedestrians now use separate footbridges alongside.
The over bridges on the line between Dumpton Park and Ramsgate, opened in 1926, are similar to that at Hythe. It will be noted that Dumpton Lane bridge has shallow beams with triangular corbels, whereas Ramsgate Road bridge has deeper beams, but no corbels.
Manor Road bridge, Bexhill is similar to the bridges at Dumpton Park.
Reinforced concrete bridges on the St Helier Loop, completed in 1930, were confined to those carrying roads over the railway. Norman Road bridge has brick abutments, whereas Tate Road bridge has concrete abutments. Both have reinforced concrete beam decks, but brick parapets, quite possibly on aesthetic grounds. Although executed in brick, the parapets resemble the concrete ones at Hythe and Dumpton Park, with the rectangular panels as a common feature.
The underbridges carrying the St Helier Loop have steel decks. Bridge 193B at Otterbourne, north of Eastleigh, has a concrete deck. The pattern of the timber shuttering can be seen on both the abutments and the deck slabs.
The concrete viaduct at Lewisham which carries the Nunhead line was built by the Southern Railway in 1928/29. It has reinforced concrete piers with engineering brick facings. Reinforced concrete beams support the viaduct deck. The parapets are also in engineering brick, but with contrasting panels in a lighter brick.
More Reinforced Concrete
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This page was created 9 January 2010