What it is called, by market
One concept, four markets. Where a name means something else locally, the card says so rather than leaving you to find out on site.
United Kingdom
Close, not identicalkerb
also kerbstone, kerb and channel
Spelled with a K. British "curb" is the unrelated verb meaning to restrain, so the spelling carries the meaning rather than being a variant.
Australia
Close, not identicalkerb
also kerb and gutter, K&G
British spelling, and "kerb and gutter" is the standard phrase for the combined edge-and-channel unit rather than two separate elements.
United Statesyours
Close, not identicalcurb
also curb and gutter, concrete curb
Spelled with a C, and normally cast in place as a continuous curb-and-gutter section rather than laid as precast units.
Canada
Close, not identicalcurb
also curb and gutter
American spelling and generally American practice — cast in place — though precast units appear in some municipal specifications.
The governing standard, by market
United Kingdom
BS EN 1340
Concrete kerb units — requirements and test methods.
United States
AASHTO / state DOT standards
Curb and gutter geometry and construction, specified by the highway authority.
Calculators for this
Each works in either measurement system, and the terminology on the page follows whichever market you have selected.
Frequently asked questions
- Is the gutter beside a kerb the same as a roof gutter?
- No, and it is the collision worth knowing about because both words are unqualified in their own trades. The gutter beside a kerb is the shallow channel formed between the kerb face and the carriageway surface, which collects surface water and carries it along the road to a gully. The gutter at a roof's eaves is a fixed channel collecting water off the roof. They share a word because they share a function — a channel carrying water along an edge — and nothing else: different trades, different materials, different standards and different calculations. A drawing note about gutter falls means one of them, and which one depends entirely on which drawing it is.
- Why is the kerb face height a specified dimension?
- Because several requirements meet at it and they pull in different directions. The face has to be high enough to contain the surfacing, to keep vehicles off the footway, and to give the channel enough depth to carry the design flow to the next gully. It has to be low enough that a vehicle mounting it at a crossing does not strike its underside, and at pedestrian crossing points it is dropped flush, or nearly so, for accessibility — which is a regulated dimension rather than a preference. So a kerb run is normally several specified heights: full face along the road, a transition, and a dropped section at each crossing and each vehicle access.
- Precast units or cast in place?
- A genuine difference in practice between the markets, and it changes the quantities and the programme rather than the design intent. British and Australian work commonly lays precast concrete kerb units on a concrete bed with a concrete backing, so the quantity is a length of units plus the bedding and haunching concrete. North American practice more often casts the curb and gutter in one continuous operation with a slipform machine or in formwork, so the quantity is a volume of concrete and the unit rate is per length of extrusion. Radii, transitions and dropped sections are where the two diverge most: precast needs specific radius units, and cast-in-place simply follows the form.