2021 DIRT Report

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811 Center (One Call Center) Transmissions, Construction Spending and Damages in the U.S.

The DIRT report has traditionally used 811 center transmission statistics and construction spending data as important indicators of overall excavation activity. More transmissions and/or more construction spending (measured in constant dollars), generally implies more digging and excavation activity.

Table 6 provides a summary of trends in transmission data from 2016 to 2021. During this period, transmissions increased each year, with 2021 transmission levels roughly 30% higher than in 2016. Meanwhile, construction spending (as measured in 2021 USD) increased by 13% over the same period. To further explore the relationship between transmissions and construction spending, an estimate of transmissions per million dollars of construction spending is also provided in Table 6. This ratio increased from 155 in 2016 to a peak of 180 in 2019, and levelling off at 177 in 2021.

Table 6—Trends in digging activity as measured by transmissions and construction spending








Total Estimated 811 Center Transmissions (Millions)







Construction Spending (Millions 2021 USD)







Transmissions Per Million Dollars of Construction Spending








Figure 19 displays the trend data graphically.

Figure 19

As noted in the 2020 DIRT report, the challenges and uncertainties that all sectors and industries faced over the last few years have added new complications for interpreting these trends over time. For instance, current inflation pressures and in particular the disproportionate rates of inflation between different sectors require a closer examination of construction spending. Similar to what was done in 2020, construction spending has been adjusted to constant 2021 U.S. dollars using a construction-specific price index.[1]

The general increase in the ratio of transmissions per million dollars of construction spending over time may be an indication of increasing 811 awareness and compliance. However, another contributor may be an issue that has generated discussion in the damage prevention industry in recent years – the use of “just in case” locate tickets. When demand is high and unpredictable, locators (contract and in-house) struggle to keep up with demand, resulting in locates being late or not getting done. In response, excavators have acknowledged requesting more locates than needed in an effort to have one jobsite ready for work on a specific start date, ensuring their crews are not idle. This adds to the total number of locates being requested without an overall increase in construction activity (or spending).

Table 7 provides a summary of damage events from 2019 to 2021 using the comparable datasets. Using this data, the standard DIRT metrics of damages per million dollars of construction spending and damages per 1,000 transmissions are reported. The results suggest a small decline in damages between 2019 and 2020 followed by a small increase from 2020 to 2021. Overall, the data supports the conclusion that damage events have been holding relatively stable from 2019 through 2021.

Table 7—Trends in damages and key indicators, based on total U.S. damages (consistent reporting entities only)





Reported Unique Damages (Comparable Dataset)




Total Estimated Transmissions in U.S.  (Millions)




Value of Construction Spending
(Millions of 2021 USD)




Damages per Dollar of Construction Spending




Change in Damages per Construction Spending




Damages per 1,000 Transmissions




Change in Damages per 1,000 Transmissions





A U.S. Department of Transportation’s Pipeline & Hazardous Materials Safety Administration (PHMSA) website[2] provides publicly available data on damages to natural gas facilities compiled from annual reports from regulated facility operators. PHMSA’s data for this population shows damage counts remaining fairly level since 2018 at around 84,000 (plus or minus 500), but damages per one call ticket trending slightly downward due to growth in ticket volumes. This is very consistent with Green Analytics’ findings.


[1] Note that the 2020 Report used the Producer Price Index for Building Materials and Supplies Dealers to capture the unique price pressures being experienced for construction materials. While these price pressures continue, over the course of 2021, broader inflation has become a greater concern. Therefore, the 2021 DIRT shifted to using broader construction sector price index: U.S. Bureau of Labor Statistics, Producer Price Index by Commodity: Construction (Partial) [WPU80], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/WPU80

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