What are intersecting arches?
Intersecting arches, also called interlaced arches, are a row of arches over columns or piers in which the arches cross one another. Each arch springs not to the next support but to the one after it, so the arches overlap and a pointed shape forms at every crossing. In Dutch they are called snijdende bogen.
Features and variants
- Geometry. Strictly speaking, a pointed arch is itself a simple form of two intersecting circular arcs.
- Decorative. Usually they form a blind arcade: a row of intersecting round arches in relief against a wall. They are a familiar feature of Norman architecture in England. Run as a band below the eaves, the motif is called an interlaced arch frieze.
- Origins. The scheme most likely originated in Islamic architecture and was later used in Romanesque and Gothic buildings.
- Modern use. Contemporary designs, such as bridges, also use arches that pass through one another.
The intersection of round arches is often cited as one possible source of the pointed arch, but it is one theory among several.
Application
- Identifying. Count the supports: if each arch leaps over an intermediate column, you are looking at intersecting arches rather than an ordinary arcade.
- Designing in brick. Set out the arches full size, including the crossing points, where bricks must be cut at an angle or special shapes used.
- Restoration. Survey radius, centres and support spacing before repairs, so the original geometry is kept.
- Structural arches. Always have a structural engineer check the load paths of crossing arches.
Common mistake: confusing intersecting arches with a round-arched frieze, where the arches stand side by side and never touch.
Related terms
- Interlaced arch frieze
- Round arch
- Lancet arch
- Blind arch
- Arcade
- Romanesque architecture
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