With innovative designs that will influence highway practice for years to come, Virginia's Smart Road has put ready-mix producer Marshall Concrete Products on the map, drawing transportation experts from all over the world to view test pavement sections and the site of what will sport the state's tallest bridge. Upon completion later this decade, the Montgomery County thoroughfare will span 5.7 miles to connect Blacksburg, Va., to Interstate 81 as part of Interstate 73.

A joint effort of Virginia Department of Transportation; Virginia Tech Center for Transportation Research (Blacksburg); and the Federal Highway Administration, the $150 million Smart Road project includes a 1.7-mi. stretch with reportedly more gadgets for measuring roadway and vehicle performance than ever assembled on a public highway. Among testing equipment and components are more than 600 pavement sensors and fiber-optic cable to gauge 12 different pavement sections.

Based in Christiansburg, with seven ready-mix and block plants in western Virginia, Marshall Concrete has supplied 2,200 yd. of material for a 2,000-ft.-long, 26-ft. wide section. Company officials note that the pavement order marked their first test of a central mix concrete capability for a highway paving order. The low slump mix (1 in. ñ 11/42 in.) was batched and loaded onto the tandem axle dump trucks of Virginia Beach paving contractor E.V. Williams Inc. The six percent grade on the project mandated that the slump not exceed 1.5 in., although VDOT specifications normally allow up to 3 inches. The air requirement of 4 to 8 percent, while normally not a challenge, was complicated by the fact that mix modifications after batching were impossible because dump trucks were used for transportation instead of mixer trucks.

More recently, Marshall Concrete has been fulfilling a contract for the Smart Road's largest single concrete order - 12,000 yd. for a bridge over Wilson Creek in the Ellett Valley. Designed by Florida's Figg Engineers, it will be only the third post-tensioned, cast-in-place structure built by balanced cantilever method in the country. Superstructure and joint work is proceeding on pace for a spring 2001 completion. VDOT and its partners are now programming future Smart Road segments.