In 1987, John Hanback of Hanback Systems Inc. of Virginia, and Robert Mendelsohn of Mendelsohn Associates, Washington, DC, approached the National Park Service with samples of artificial slate shingles fabricated with lightweight concrete. The NCR showed interest in using the technology to create an artificial stone guardwall for a parkway.
Hanback Systems, Mendelsohn Associates, the NPS, Denver Service Center, and the FHWA all met at Shenandoah National Park to discuss the project. The group decided to build a wall for the Baltimore-Washington Parkway, which needed thousands of feet of median.
Smith-Midland Corp. signed a $40,000 contract with the FHWA to produce a test section of wall, in order to meet visual approval by the FHWA, then produced an 80-foot section of wall for crash testing. The precast wall was found to be equal, if not better, than the original stone masonry guardwall, at a savings of more than $2 million for 55,813 feet of stone wall.