Where Are Those Pesky Pipes?
Whether above ground or beneath it, municipalities need to know where utilities are located. This is true when installing water, sewer, electric, gas, or communications lines, and it is even more important once those lines have been in place for some time. When laying out residential or commercial districts, surveyors are called upon to accurately mark where each respective utility line should run. Later on, construction and excavation projects require the precise location of existing utilities to prevent damage and also allow for follow-on connectivity. While a map can be quite useful to help narrow down a spot where a gas line should be, it's always a good idea to engage a surveyor to know exactly where you should plant that new maple tree.
Above the Ground
Utility companies are usually government-run or private/public entities operating under some sort of regulation. The utility infrastructure generally consists of two types of assets-what is above the ground and everything that is below it. The former would include things like electrical substations and power transmission lines, gas wellheads, telephone or other utility poles, and manhole covers for sewer systems. While it is hardly a challenge to identify the exact location of a transmission tower-the 30-meter-tall steel lattice-type structure and long, saggy wires is usually a dead giveaway-the presence of a utility surveyor was certainly necessary to determine the initial placement of that tower and how far apart each tower could be situated. Utility surveyors work closely with engineers to set out utility grids so that the maximum amount of spatial coverage can be achieved with a minimal amount of pipes, wires, and so on. Some of the equipment most useful to utility surveyors in aboveground applications includes GPS surveying systems, total stations (which stand in for the old, non-electronic surveyor transits), digital levels, and a wide selection of mapping software.
Below the Ground
During the installation process, the location of what will eventually become underground utility lines is clearly marked on a series of maps. These maps come into play whenever subsequent work needs to be done in the area. Whether a sewer needs cleaning, a gas main warrants checking for leaks, or a water pipe has burst, utility workers require accurate knowledge of the location of utility assets. There are certain standards that each utility follows. For example, all underground facilities are measured to their center point or centerline, where the size of the structure is also indicated. As an example, the line on a map that traces a water pipe follows the center of that pipe. A notation at regular intervals, or a key that may be color-coded, will indicate that the pipe in question has a diameter of 20cm. This means that anyone digging more than 10cm either side of that line will miss hitting the pipe. Because many of the buried utility lines are made of metal or have metal components, magnetometer devices are extremely useful in determining the exact location of an underground course. Once a utility surveyor determines the path of an existing line, he or she will mark the location with spray paint, ribbons, or staked flags. Many communities in the world have standardized their utility markings, where electric is red, sewer is green, water is blue, communications is orange, and gas or oil is yellow. In this manner, anyone transferring from one municipality to another will not mistake one type of utility line for another.