The renovation of historical protected structures usually presents the architect with an array of unusual problems.  Complicate a project with height limitations, footprint limitations and the need for additional parking, and the solution will usually require that the site be fully developed below grade.  Add to this the need to undermine and support buildings constructed in 1893, 1910 and 1972 and you now have an outline of challenges RTKL faced in adding 25,000 square feet of office and parking space to the American Trucking Association building in Washington, DC.

To minimize movement of the structures and to control risk, Schnabel designed a sequence of construction that would allow the new shear walls to sequentially pick up loads, as each building was undermined.  The site is continuously monitored with real-time readings that would alert movement in minutes of any settlement.  The system is so sensitive that Schnabel Foundation Company would get alerts when an excavator’s bucket would scrape a structure’s foundation.  Even with this level of sensitivity and precision, measurements of the movements to date have been within the system’s accuracy; no measurable movement.