The National Park Service (NPS) contracted with Smith-Midland, Midland Va., to produce 100 linear feet of experimental precast guardwall. The company undertook the project at some risk, because the NPS would not pay if the wall was not visually pleasing. But the risk paid off. Smith-Midland is currently engaged in a joint venture with Back River Supply, Baltimore, to produce several miles of the concrete guardwalls for the Baltimore/Washington Parkway.