WHAT IS HEIGHT MODERNIZATION?
Height modernization is a program of the National Geodetic Survey, the nation's positioning agency. The program is to enhance the vertical component of the National Spatial Reference System (NSRS). The NSRS is a consistent national reference framework that specifies latitude, longitude, height (elevation), scale, gravity, and orientation throughout the United States. NSRS provides accurate knowledge of the size, shape, and position of our environment, as seen in the design, construction, and safety of roads and buildings, the transportation of goods and people by car, ship, or plane, as well as in the monitoring and protecting of our environment. The horizontal component of the NSRS is in place and functioning. The vertical component of the NSRS is not, and therefore the full potential and national benefits of real-time measurement of heights are not yet a reality.

NATIONAL HEIGHT MODERNIZATION PROGRAM
In 1998, the U.S. Congress directed the National Geodetic Survey, the nation's positioning agency and an office within the National Oceanic and Atmospheric Administration (NOAA), Department of Commerce, to conduct a National Height Modernization Study. The purpose of the study was to determine the effectiveness of height modernization in California and North Carolina, and its potential benefits to the nation. Up until the time of the study, there were many indications that considerable efficiencies and cost savings could be achieved through the utilization of Global Positioning System (GPS) technology when applied to surveying and in particular, the measurement of heights. This study proved this and projected in some cases a 90 percent cost savings over conventional surveying methods. Moreover, the study indicated the emergence of many height modernization applications ranging from improvements to air and marine navigational safety, to precision farming and mining, and from high accuracy flood mitigation and mapping to real-time monitoring of gravity and aquifer-based water systems. These findings caught the attention of Congress and the Administration, and over the past six years, more than $18 million has been appropriated with 90 percent going to participating states to initiate the implementation of the study nationwide.