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What is Utility Locating? Learn All That it Encompasses


What Exactly is Utility Locating?

Utility locating is the method of accurately determining the whereabouts of underground utilities. It requires the use of technology specifically designed for the purpose. This specialized equipment must be operated by qualified technicians following strict locating procedures. Utility Survey Corp.’s 10-Step Utility Locating Protocol™ sets the standard for this. The utility locating technician will mark the position of all detected utilities on the ground with color-coded paint or chalk or flags or stakes.

The choice of a marking medium will depend on the ground conditions (ie paint/chalk for a hard surface such as blacktop or concrete, flags/stakes for a soft surface such as soil or sand). The color-codes must conform to industry standards.

Utility Locating Terminology

“Utility Locating” is a very general description. It is probably the most commonly used term but there are also several others – which can be confusing. The following will explain these terms and help you be clear about what you should expect to be getting when asking for an Underground Utility Locating Survey.

Utility Locating

“Utility Locating” is also often referred to as a “Locate” or a “Markout”. However, none of these three common descriptions calls for, or implies, any specific methodology or the use of any particular piece of equipment. And that could result in two particular problems occurring for the unwary:

1. The client doesn’t fully understand what it is exactly he or she will be getting. They could believe they will be getting a comprehensive utility locating service when in fact they’re not - and that could lead to something really bad happening.

2. An apples-for-apples service provider comparison is impossible because there isn’t enough information with which to make a comparison. This could lead to someone showing up to do a job they’re not equipped for, trained for, or capable of doing in the way a professional utility locating project should be carried out. This could also result in a bad outcome.

Ground Penetrating Radar

The most often misstated description we hear when people call US for a utility locating survey is to ask for a “Ground Penetrating Radar Survey” or “GPR Survey” or simply, a “Radar Survey”.

These descriptions are misstated because there is an incorrect assumption that Ground Penetrating Radar (GPR) is all that’s needed to successfully find all utilities. However, GPR cannot be guaranteed to do that.

GPR is a very expensive, high-tech, piece of equipment but it should never be used as a stand-alone to undertake a comprehensive utility locating survey. It cannot and will not find all utilities all of the time. To believe it will is a potentially dangerous misconception.

X-ray the Ground

“X-raying” is what prospective clients typically confuse with Ground Penetrating Radar. We wish we could “X-ray the Ground” and see what’s there” but it’s impossible.

Even if it was possible to x-ray, the radiation given off would make for too hazardous a work environment to be practical.

Ground Penetrating Radar is the only locating technology that has the ability to “look” into the ground. But, as good as GPR is at what it can do, it does come with its own limitations too, as already discussed.

Toning or Scoping

“Toning” or a “Tone-out” and “Scoping” are terms that tend to refer specifically to Electro-Magnetic Radio Frequency (EM/RF) locating instruments. These instruments can only find utilities made of metal; ie a steel water pipe, an electric cable, telephone wire etc. The instrument sounds off a tone when it detects a utility; hence the term.

It’s usually those who are familiar with the public utility One-Call type locating service, such as contractors and excavators for example, who tend to use the term “tone” or “tone-out” or “scoping”. This is because the One-Call industry only uses EM/RF-type locators.

Not only that but the typical One-Call locator will only have one of these instruments when they go out to “tone a line”. And, if that particular instrument’s operational frequency is not able to find the “line” that’s too bad. This is a serious limitation in the quality of service a client can expect.

Utility Survey Corp.’s locating professionals carry at least three different types of EM/RF locating instruments. This is because there isn’t any one EM/RF instrument that will work effectively in all conditions. Different instruments come with different operational frequencies and one instrument may find the pipe or cable when another cannot.


The term “Scanning” is about as close as it gets to a reasonable description when the client understands they need a thorough, professional, utility locating service.

However, the question, “Scan with what?” isn’t usually covered or thought out. And, that’s a very important omission. Scanning with just Ground Penetrating Radar isn’t enough. Scanning with just an EM/RF locator isn’t enough either.

A comprehensive utility “Scan” should be, and can only be carried out effectively by using a combination of Ground Penetrating Radar and EM/RF locators – that must be operated by professional technicians who are trained, skilled, and experienced in their use.

Utility Survey Corp.’s 10-Step Utility Locating Protocol™ will give you this.

Our experienced utility locating team provides services to excavators, concrete and construction professionals, environmental and engineering consultants and property owners throughout NY, NJ, CT, PA and the whole northeast.