Utility location is the process of identifying and labeling public utility mains that are underground. These mains may include lines for telecommunication, electricity distribution, natural gas, cable television, fiber optics, traffic lights, street lights, storm drains, water mains, and wastewater pipes. In some locations, major oil and gas pipelines, national defense communication lines, mass transit, rail and road tunnels also compete for space underground.
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Description
Public utility systems are often run underground; some by the very nature of their function, others for convenience or aesthetics. Before digging, local governments often require that the underground systems' locations be denoted and approved, if it is to be in the public right-of-way.
Because of the many different types of materials that go into manufacturing each of the different types of underground lines, different detection and location methods must be used. For metal pipes and cables, this is often done with electromagnetic equipment consisting of a transmitter and a receiver. For other types of pipe, such as plastic or concrete, other types of radiolocation or modern ground-penetrating radar must be used. Location by these technical means is necessary because maps often lack the pinpoint precision needed to ensure proper clearance. In older cities, it is especially a problem since maps may be very inaccurate, or may be missing entirely.
A few utilities are permanently marked with short posts or bollards, mainly for lines carrying petroleum products. This may be done because of venting requirements, and also serves to indicate the location of underground facilities that are especially hazardous if disturbed.
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Telephone hotlines
"Call before you dig", "Know What's Below! Dig With Confidence!", "Dial before you dig", "Digger's Hotline", "One-call", "Miss Utility", "Dig Safe", "Click before you dig", or Underground Service Alert are services that allow construction workers or homeowners to contact utility companies, who will then denote where underground utilities are located via color-coded markings typically up to and not past the user's service connection or meter. Lines on the other side of the meter or service connection are considered to be part of the customer's property and will typically not be located by these services.
Failure to call such a number ahead of time may result in a fine or even a criminal charge against a person or company, particularly if such negligence causes a major utility outage or serious accident, or an evacuation due to a gas leak. Hitting a water main may also trigger local flooding or require a boil-water advisory.
The following are the partial list of countries with one-call for utility location:
- Australia: The national "dial before you dig" number is 1100.
- Canada: In Canada, there is no unified number for the country. However, it has the "Click Before You Dig" website that provides access to the hotline for each of the provinces.
- United States: As required by law and assigned by the US Federal Communications Commission (FCC), the 8-1-1 telephone number is used for this purpose across the United States.
- United Kingdom: In Scotland there is an online web based service called Vault (short for Scottish Community Apparatus Data Vault), which allows registered users to specify a polygon on a map and immediately obtain an interactive map of all major undertakers owning underground assets, except the principal telecoms operators). In the rest of the UK, there is no dial-before-you-dig service. Instead the onus is on excavators to ensure that they do not damage buried services. This has resulted in a class of locating tools which are simpler to use, and are called Cable Avoidance Tools (CATs), and the associated signal detectors are called Gennys.
Color-coding
Utility color codes are used to identify existing underground utilities in construction areas, to protect them from damage during excavation. Colored lines, flags, or both are used to mark the location and denote the type of underground utility. A special type of spray paint, which works when the can is upside-down, is used to mark lines, often in a fluorescent color. On flags, a logo often identifies the company or municipal utility which the lines belong to.
Flags may also be an advertisement for a company which has installed an irrigation system for lawns or gardens. In this case, each sprinkler head is usually marked, so that landscaping crews will not cover or bury them with soil or sod, or damage them with tractors or other construction equipment while digging holes for trees, shrubs, or other large plants or fenceposts. This is also important because a vehicle (tractor, truck, or otherwise) can break a sprinkler or the hard-PVC pipe or joint it is mounted on, simply by driving over it, particularly on newly moved soil which is uncompacted and therefore unsupportive of such weight.
Australia
The national standard for Australia uses the following color guide:
United States
In the United States, the American Public Works Association (APWA) Uniform Color Codes for temporary marking of underground utilities are listed below:
Some municipalities use the pink paint to make lines and codes on the pavements related to required street improvements such as ramp replacement, asphalt grinding and form injection. These markings are not related to utility locating.
In Canada, the provinces adopt the use of APWA Uniform Color Codes.
India
The India uses a convention similar to the US one, for marking underground utilities, such as telephone, gas, water and electricity. The system is based entirely on convention without any written standard. These markings are color-coded, and are painted by contractors onto the pavement.
The main colors based on the convention are used in the same way as in the US: red for electricity; yellow for gas; blue for water. However, other colors have other meanings. Green is used for telecommunication conduits. White is used as general communication between contractors. It is also used to note the details of road surface markings so that markings can be easily restored after the road construction is completed. A few telecommunication companies also use white color for their utility locations. Orange and other colors are used by local authorities to mark improvements and other details not related to utility locations.
Source of the article : Wikipedia
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