The simplest form of arch is the round-headed or semi-circular
design. The form-work off which it is built is easily set out, and thrust
against the abutments is minimised. However, a round-headed arch has large
spandrels, so requires more material than other arch forms. This also means
that the bridge weighs more and will need stronger footings. The curve of the
arch gives limited clearance at the side, so round-headed arches are not
suitable for low bridges.
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Bridge 103, Dartford Road, Farningham Road, photographed on 30th
September 2007.
photograph by Gregory Beecroft
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| Bridge 505, Hillbury Road, Upper Warlingham, photographed on 26th
August 2007
photograph by Gregory Beecroft
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Both of these bridges are a considerable height above the road, so clearance
under the arch is not a problem
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Peters Finger Road bridge, Salisbury, photographed on 2nd May 2009.
photograph by Gregory Beecroft
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| Damage to Peters Finger Road bridge, Salisbury.
photograph by Gregory Beecroft
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Peters Finger Road bridge, on the Romsey line near Salisbury, has quite a
low round-headed arch. It bears the scars of regular collisions with road
vehicles. A bend in the road makes this bridge particularly vulnerable.
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Enid Street, between London Bridge and South Bermondsey,
photographed on 14th October 2007.
photograph by Gregory Beecroft
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| Ropetackle Arches, Shoreham-by-Sea, photographed on 6th October
2007.
photograph by Gregory Beecroft
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Viaducts often have round-headed arches, because it is helpful to reduce
lateral thrust.
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Forge Bridge, Hooley, photographed on 25th August 2007.
photograph by Gregory Beecroft
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| Joliffe Road bridge, Merstham, photographed on 25th August 2007.
photograph by Gregory Beecroft
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Round-headed arches are often found spanning deep cuttings. These two
bridges cross the Brighton line between Coulsdon and Merstham. Joliffe Road
bridge has a middle arch over the tracks and side arches over the cutting
slopes. It also has relieving arches piercing the bridge piers, as a means of
reducing the number of bricks used and, therefore, the weight and cost of the
structure. Three-arch bridges are quite commonly found crossing cuttings. The
huge and impressive single arch bridge at Hooley is less usual and arches of
this size are rare. There is a second bridge very like this one at Hooley, but
it has been subject to significant modification, with pavements cantilevered
out from it, and a pipe bridge is immediately adjacent.
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Bridge 838, Northfleet, photographed on 16th August 2008.
photograph by Gregory Beecroft
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| Bridge 816, Marden, photographed on 20th October 2007.
photograph by Gregory Beecroft
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Accommodation bridges, allowing access between fields on either side of the
railway, and those for minor lanes, did not require significant headroom, so
were often round-headed arches. The arch at Marden is exceptionally small and
has given its name to a new street of houses nearby, Barrel Arch Close.
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