Abstract: A precast concrete wall on a prepared subgrade, comprises standardized, precast, reinforced concrete foundation, wall and cap modules. The cap modules include parapets on opposed sides and an elevated roadway therebetween. A plurality of tie down rods, each extending through the cap modules, two or more courses of wall modules and at least partially into the foundation modules. An optional anti-tunneling barrier is provided in the subgrade, below the foundation. A method of constructing the wall includes specifying standardized reinforced concrete foundation, wall and cap modules so that they can be manufactured by multiple suppliers, and providing a logistical model to minimize shipping costs by matching each point of fabrication with the appropriate point of delivery.