Here's how they are building their guideways in Washington, DC
(Dulles Corridor Metrorail Project - June Newsletter:
http://www.dullesmetro.com/pdfs/10JUN_DullesMetroNewsletter.pdf)
The truss located on the Dulles Connector Road is now in action as it lifts the segments to build the aerial guideway tracks.
Photo by Stephen Barna, Dulles Corridor Metrorail Project
Inside the connected segments being built as part of the aerial guideway.
Photo by Dulles Corridor Metrorail Project