PLACING MARKS ON THE GROUND to represent the position of underground utilities is traditionally done for two separate but distinct purposes: damage prevention and design survey. Both missions are vital and necessary to protect the health, safety, and welfare of the public. However, it is important for utility owners, their contract locators, and excavators to be able to distinguish between these purposes.
There is a written guideline for markings for damage prevention purposes that is published by the American Public Works Association (APWA) as part of the uniform national color code for utilities. Basically, it says that utility markings should be represented by a single 2” wide paint mark of 6” length in the appropriate color (See Figure 1). Other accompanying marks such as offset indications, ownership, size of utility, number of cables represented by one mark, and so forth are also allowed.
Figure 1 (Above): Markings for damage prevention purposes, in this case a water line. There has never been a written guideline for markings for design purposes; however, a workaround of using pink as a “survey mark” has been in use in several states. Many other systems over the years have been proposed and tried, only to have recognized shortcomings.
The Utility Engineering and Surveying Institute of ASCE recommends that rather than a single 2” wide mark of approximately 6”, a mark for design consists of a 1” wide and very short 2-3" long dash – dot – dash line code (See Figure 2). The dots in the middle can be any color and the dashes on each side are silver. The dots tell the SUE surveyor which line segment it connects to, and the silver dash indicates direction or end point.
This system retains all the benefits of coding to distinguish different utilities, necessary for the engineer especially in congested environments, while clearly differentiating marks for design versus damage prevention. Constructors can easily be educated through normal means such as trade meetings, magazines, etc. as to these differences.
It is the recommendation of the American Society of Civil Engineer’s (ASCE) ASCE 38-22 standards committee (Standard Guidelines for Investigating and Documenting Utilities) that such a system be adopted on a national basis.