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Railway Structures
Brick bridges: Round-headed or semi-circular arches

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.
Dartford Road bridge, Farningham Road Bridge 103, Dartford Road, Farningham Road, photographed on 30th September 2007.

photograph by Gregory Beecroft

 
Bridge 505, Hillbury Road, Upper Warlingham, photographed on 26th August 2007

photograph by Gregory Beecroft

Hillbury Road bridge, Upper Warlingham

Both of these bridges are a considerable height above the road, so clearance under the arch is not a problem

Peters Finger Road bridge, Salisbury Peters Finger Road bridge, Salisbury, photographed on 2nd May 2009.

photograph by Gregory Beecroft

 
Damage to Peters Finger Road bridge, Salisbury.

photograph by Gregory Beecroft

Damage to Peters Finger Road bridge, Salisbury

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.

Enid Street arches, London Bridge Enid Street, between London Bridge and South Bermondsey, photographed on 14th October 2007.

photograph by Gregory Beecroft

 
Ropetackle Arches, Shoreham-by-Sea, photographed on 6th October 2007.

photograph by Gregory Beecroft

Ropetackle Arches, Shoreham-by-Sea

Viaducts often have round-headed arches, because it is helpful to reduce lateral thrust.

Forge Bridge, Hooley Forge Bridge, Hooley, photographed on 25th August 2007.

photograph by Gregory Beecroft

 
Joliffe Road bridge, Merstham, photographed on 25th August 2007.

photograph by Gregory Beecroft

Joliffe Road bridge, Merstham

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.

Bridge 838, Northfleet Bridge 838, Northfleet, photographed on 16th August 2008.

photograph by Gregory Beecroft

 
Bridge 816, Marden, photographed on 20th October 2007.

photograph by Gregory Beecroft

Bridge 816, Marden

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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