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Outgoing Transmissions – Measure of Damage Prevention Activity

While incoming locate requests are a useful indication of the amount of digging activity taking place across the country, outgoing transmissions (defined below) provide a possibly more accurate view of the potential for buried facilities to be impacted by excavation activity. Additionally, outgoing transmissions* provide us with greater insight into the overall impact each locate request has on the damage prevention process. 

*Outgoing Transmissions—The number of initial notices of intent to excavate sent by 811 centers to their member facility operators, including those sent directly to locating vendors on behalf of members. Each incoming locate request generates outgoing transmissions to several members, such as electric, gas, cable TV, water, sewer, telecommunications, etc.

The fact that the percentage increase in outgoing transmissions was less than that of total incoming notifications indicates that 811 centers are becoming more efficient at filtering out notices that do not need to be transmitted to member operators. For example, electronic white-lining* leads to a more accurate description of the work site, enabling the 811 center to identify the member facility operators impacted (or not) more accurately. 

*Electronic White-Lining (EWL):[1] The process in which an excavator identifies where proposed excavation will occur by drawing a polygon shape on a GIS map; that shape is delivered electronically by the one-call center to its member facility operators.

Total Outgoing Transmissions: Green Analytics, CGA’s statistical consultant, was able to estimate the total number of U.S. transmissions in 2021 to account for the 811 centers that did not submit annual statistics. Its estimate was 288.3 million, a 5% increase over its 2020 estimate of 273.9 million.


[1] At the time of this report’s publication, the Best Practices Committee had approved this definition for inclusion in the Best Practices Glossary of Terms and Definitions. If approved by the CGA Board of Directors, it will be included in the next Best Practices edition (19.0).

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