the tyvola viaduct is the longest elevated portion of the entire blue line. the bridge spans a distance of 3/8 mile (0.6 km) crossing both tyvola road and an active norfolk southern rail crossing just south of tyvola. tyvola was selected for an overpass as a result of its crossing having the highest traffic count of any other along the route with an estimated 45,000 vehicles a day. beginning on january 4, 2006, the installation of the concrete girders, ranging in size between to , commenced for the construction of the elevated sections. all pieces were in place by february.