02What the spray paint on the street means

The short version: Bright paint dashes, arrows and letters on pavement or grass are almost always locate marks: a utility's locator has shown roughly where a buried line runs because someone is about to dig. In the US, the color tells you the kind of utility (red electric, yellow gas, orange communications, blue drinking water, green sewer, purple reclaimed water, pink survey, white proposed dig), and the letters tell you who owns it. The marks show an approximate path, not an exact one, so excavators hand-dig in a band on each side. In the US, anyone planning to dig, even for a mailbox post, contacts 811 first (Dig Safe in Massachusetts, Maine, New Hampshire, Rhode Island and Vermont).

What do the colors mean?

What you see: Short dashes, lines and letters in red, yellow, orange, blue, green, purple, pink or white, often several colors in one spot.

Each color stands for a type of buried facility under the APWA uniform color code. The Common Ground Alliance (CGA), the US damage-prevention body, recommends in its Best Practices (Version 20.0) that the APWA code, referenced as ANSI Z535.1, be adopted nationwide for marking dig sites and buried facilities, while leaving any state free to specify other colors.⁴⁵ ANSI publishes the colors as the "American National Standard for Safety Colors."⁶

This code is for buried utilities. Painted traffic lines follow a separate system, covered in road lines, and pink survey paint is explained with survey marks.

The color only warns of the type of hazard.⁶ It does not say who owns the line, how deep it is or how big it is; that is what the letters are for. Paint on a lawn looks alarming, but locators use flags or a special marking paint, and neither does long-term harm to grass.⁷

What do the letters next to the paint mean?

What you see: Letters such as "W", "G", "E", "FO" or "TEL", or a company name, in the same color as the dashes, sometimes with sizes like 12" STL.

The letters identify the owner and the facility. CGA recommends a fixed order: company identifier, then facility type, then construction, then material, written with slashes, for example "TELCO/TEL/FO/PLA" (a telecommunications company's fiber optic line in plastic conduit).⁸ One state one-call center's guide says the company name must always appear at the top or to the left.⁶

Source for all three rows: CGA's Common Abbreviations.⁸ Field crews often write "CATV" for cable TV, but CGA's list uses "TV."

Owner letter codes are local. In Virginia, for example, the notification center assigns each operator its letters, and the state manual adds "RF" for buried RFID markers, "HDD" for a line installed by horizontal directional drilling, and a green "T" where a sewer lateral meets the main.⁹

What does "NO" spray-painted on the ground mean?

What you see: "NO" followed by a company name or code, such as "NO TELCO," painted in a utility color, or a clear plastic flag with writing on it.

This is a no-conflict mark: the owner checked and has nothing in the way of the planned dig. CGA's guidance is "NO" plus the owner's identifier in that owner's APWA color. Companies that run more than one kind of system add a facility code, as in "NO GASCO/G/D" (no gas distribution line here).¹⁰ A slash through a letter carries the same meaning in some states.⁶ CGA also describes clear translucent "No Conflict" flags carrying the owner's identifier, phone number, a space for the ticket number and the date.¹⁰

A no-conflict mark speaks only for that owner. Another company's line can still be there.

What do the arrows, H-shapes and numbers mean?

What you see: Dashes with arrowheads, an "H" drawn across a pair of lines, numbers with inch marks, or "OFF" with a distance.

CGA describes locate marks as roughly 12 to 18 in. long (30 to 45 cm) and 1 in. (2.5 cm) wide, spaced about 4 to 50 ft (1.2 to 15 m) apart.¹⁰ State manuals vary: Virginia calls for marks about 8 to 10 in. long and 1 to 2 in. wide, no more than 20 ft (6 m) apart, with at least three marks per line.⁹

The shapes, per CGA's field delineation guidelines:¹⁰

• Single line over the center. A single facility is marked over its approximate center.
• "H" shape. A wide facility can be marked at its two outside edges, joined by a bar, so the mark looks like an H.
• Count and size. Several facilities together show the count and size, e.g. "4/4" PLA" for four 4-inch plastic ducts. A corridor of unknown count shows its width, e.g. "12" CDR."
• Arrow. Shows a change of direction or a lateral branching off.
• Offset. An offset mark sits to one side of the line with a direction and distance and the label "OFF," used when a mark cannot go directly over the facility.
• Casings. Noted in words, e.g. "6 in. plastic in 12 in. steel."

Virginia's manual adds that arrows can show a line continuing beyond the ticket area, that offset arrows carry the distance on the right and size, material and operator letters on the left, and that a "hump" symbol shows two lines crossing without saying which is on top.⁹ Gopher State One Call's guide shows a diamond for conduit.⁶

What are the little flags and plastic whiskers in my yard?

What you see: Small colored plastic flags on wire stems, wooden stakes, or tufts of colored plastic bristles poking out of grass or gravel.

These are locate marks in another form. CGA lists paint, flags, stakes and whiskers, or a combination, as marking methods.¹⁰ Virginia's manual calls for flags, stakes or whiskers where paint will not last or will not show: high-traffic areas, landscaping, snow and loose soil.⁹ The colors follow the same code as paint. Whiskers are tufts of colored plastic strands driven into the ground; CGA names them as a method without describing them further.

Leave them in place until the work is done. Locators and excavators rely on them, and a pulled flag can mean a missed line.

What does white paint mean before digging?

What you see: White dashes, dots, an outline or white flags around a patch of ground, sometimes with a contractor's initials, before any colored marks appear.

White is the digger's paint, not the utility's. White-lining (or premarking) outlines where an excavator plans to dig, so locators know which lines to look for. CGA Practice 5-2 describes white dashes about 6 to 12 in. long and 1 in. wide, about 4 to 50 ft apart; 1 in. dots for arcs; a continuous line around a single-point site; centerline arrows for trenching or boring; and white stakes, flags or whiskers carrying the excavator's identifier. A single white center stake can mark a site within a 50 ft (15 m) radius.¹¹ Virginia's white lining shows the width in feet on either side of a centerline.⁹

In Massachusetts, premarking with white paint or stakes is required before any excavation, even on private property, and before calling Dig Safe.² Dig Safe adds that digging outside the premarked area needs another ticket.¹²

How close to the marks can you dig?

What you see: Nothing painted, but the crew puts down the excavator and picks up shovels or a vacuum hose near the marks.

The marks are approximate, so there is a no-machine band around them called the tolerance zone. CGA Practice 5-19 defines it as "the width of the facility plus 18 in. on either side of the outside edge of the underground facility on a horizontal plane," and says it is not meant to override state rules that specify more than 18 in.¹³ That is about 46 cm on each side.

Dig Safe tells excavators to use non-mechanical methods within 18 inches of a marked facility.¹² Massachusetts treats marks that are off by more than 18 inches as inaccurate and says to hand-dig near them.² Some states use a wider zone.

New York is one of them: National Grid's contractor guidance gives New York's zone as "one-half of the known diameter plus 24 inches on either side of the designated centerline," against 18 inches on either side of the marks in Massachusetts and Rhode Island.¹⁴ In Texas, a 2017 federal summary of state law lists 18 inches for intrastate pipelines.¹⁵

How long do the marks last?

What you see: Faded marks, or fresh marks painted over older ones in the same place.

Paint fades on its own schedule, but the legal life of the marks is set by the ticket, the record of a dig request. In Massachusetts a ticket is valid for 30 days and must be renewed at least 72 business hours before it expires; utilities must mark by the time the ticket becomes valid, re-mark within 24 hours when asked, and the marks must be kept clearly visible.²

Ticket life differs even among the five Dig Safe states: 30 days in Massachusetts, New Hampshire and Vermont, 60 days in Maine, and no expiry in Rhode Island as long as the marks are maintained.¹² So a fresh coat over old paint usually means a new or renewed ticket.

What is 811?

What you see: "Call 811 before you dig" on utility trucks, door hangers, pipeline markers and paint cans.

811 is the US three-digit number that routes callers to their state's one-call center, the organization that takes dig notices and passes them to member utilities. The Pipeline Safety Improvement Act of 2002 provided the basis; the FCC designated 811 for state one-call systems in an order released March 14, 2005, published in the Federal Register on April 13, 2005, and gave phone carriers two years from publication to implement it.¹ The number launched nationally on May 1, 2007, at a press conference with CGA, Transportation Secretary Mary Peters and the FCC, where officials cited "more than one unintentional hit per minute every day, every year."¹⁶

What counts as digging is broad. Massachusetts includes grading, backfilling, demolition and even installing a mailbox, and requires notice at least 72 business hours ahead, not counting weekends and holidays.² Member utilities mark only the facilities they own or maintain.¹² A line the homeowner owns, such as a cable out to a garage, falls outside that.

How often do people hit buried lines?

What you see: Nothing on the street, but this is the reason the paint is there.

CGA's annual Damage Information Reporting Tool (DIRT) report counts reported damage to buried facilities. For 2024 it counted 196,977 unique damage reports, and the CGA Index rose from 94.0 in 2023 to 96.7 in 2024, leaving the industry off track for its "50-in-5" goal.¹⁷

The leading root causes in 2024:¹⁷

The top 10 causes made up 85 percent of damages. Across eight 811 centers, excavators had an average 38 percent chance of not starting on time because locate responses were incomplete.¹⁷ Roughly one damage in four came from a dig where nobody called.

For what happens after a hit on a gas main, see the sister guide's section on gas and steam.

In Boston

In Boston, as in the rest of Massachusetts and in Maine, New Hampshire, Rhode Island and Vermont, the one-call center is Dig Safe.¹² The state rules, in short:²

• White-line the dig area first, even on private property.
• Contact Dig Safe (811, or (888) 344-7233) at least 72 business hours before digging.
• The ticket lasts 30 days; renew it at least 72 business hours before it runs out.
• Hand-dig near the marks; marks should be within 18 inches of the facility.
• Penalties run up to $200,000 per violation for natural gas lines; for other facilities, $1,000 for a first offense and up to $10,000 for later offenses within 12 months. The Department of Public Utilities' Pipeline Safety Division enforces the law under G.L. c. 82 sections 40-40E and 220 CMR 99.00.

Massachusetts does not require municipal water and sewer departments to join Dig Safe.² That matters for blue and green marks: a city water line may not be marked through a Dig Safe ticket unless the department is a member. The sister guide covers how the city's water system is laid out.

The Boston Water and Sewer Commission runs its own water and sewer mark-out request form, separate from a Dig Safe ticket. As of 2026 its page asks for white premarking first, at least three business days' notice and no more than 30 days, recommends that the contractor rather than the owner make the request, and calls for non-mechanical digging within 18 inches of its marks.¹⁸

Dig Safe's excavator manual asks that each owner be identified by initials or company name in letters 6 in. high at the start and end of a locate and every 100 ft on long ones.¹⁹ For the rest of the city's street hardware, see Boston.

Elsewhere in the world

Canada. There is no single national number, and 811 is not Canada's national number. Each province runs a center: Alberta One Call, BC One Call, Manitoba's Click Before You Dig MB, Ontario Dig Authority, Sask 1st Call, and Info-Excavation for Quebec, New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland, with clickbeforeyoudig.com as the national portal.²⁰

United Kingdom. The UK works from plans more than from paint. LinesearchbeforeUdig (LSBUD) is a free online service where diggers search the networks of over 150 asset owners covering electricity, gas, high-pressure fuel, water and fiber; not every owner is a member, so users must contact the rest themselves.²¹ The Health and Safety Executive's guidance HSG47, "Avoiding danger from underground services" (third edition, 2014), makes locating and identifying buried services part of a safe system of work.²² Professional utility surveys follow BSI PAS 128, first published in 2014 and revised by ICE and BSI in 2022; it covers detecting, verifying and locating active, abandoned and unknown utilities, with quality levels based on survey type, location accuracy, post-processing and supporting data.²³

Australia. Before You Dig Australia (BYDA), formerly Dial Before You Dig, is a free national referral service: a web enquiry goes to asset owners near the site, who reply with plans.²⁴ BYDA also runs "Look Up and Live" for overhead power lines.²⁵ BYDA sends plans; any marks on the ground come from whoever does the locating.

Paint colors abroad. Canadian practice largely follows the US code: the City of Windsor, Ontario, says it and local utilities use the APWA uniform color code, with the same eight colors.²⁶ According to the design publication 99% Invisible, the UK shares many US colors but uses green for telecom rather than sewers, and Australia has its own system with orange for electricity, white for communications and cream for sewage.²⁷

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