When a 2011 earthquake damaged the Washington Monument, the scaffolding installed for the repair work provided a rare opportunity to survey the peak of the structure.
On the afternoon of August 23, 2011, people from Delaware to New York experienced something unusual – the shaking and rolling of a 5.8 earthquake. While the epicenter of the quake was in Mineral Virginia, its energy quickly spread through the bedrock, which led to mild structural damage in the Washington, DC area, including the Washington Monument. When the repair work started in 2013, the scaffolding put in place not only provided access to the construction crews, but also to a team of surveyors. What was the rationale for conducting a new survey?
The Purpose of New Washington Monument Survey
The National Geodetic Survey, in conjunction with the National Park Service, decided to take advantage of the rare access to the peak of the Washington Monument to obtain new survey data. The rationale for obtaining new data was to improve the accuracy of the data in the National Spatial Reference System and to compare the information gleaned from a modern survey to historic data. What were the results of the new Washington Monument survey?
The Amazing Accuracy of the 1885 Data
When you think about the high-tech equipment used by surveyors today, it is reasonable to assume data from surveys conducted more than a century ago would not be as accurate. Surprisingly, when the survey team compared their data with the 1885 survey, they found the measurements to be accurate within ¾ inches. Additionally, when they compared their location data with that from a 1999 survey, they found the older measurements to be accurate within 2.0 mm.
What are the advantages of modern high tech surveying tools?