Just got this tidbit from DART:
Orange Line: From 7 a.m. to 5 p.m. Tuesday, March 10 through Friday, March 13, there will be a temporary left lane and shoulder closure on southbound 482 between Justice Way and the 482 Trinity Bridge. One lane will remain open to traffic. Crews will be drilling for soil samples necessary for design and construction of the Orange Line in that area.
In fact, DART's Rail Construction page is now issuing regular messages about "pre-construction activities". That, plus the pretty pictures of rails being delivered to staging areas near Texas Stadium (on the Orange Line Expansion page) makes me think the project is far enough along to warrant a new thread.

But it's still early... if DART hits a snag before work begins in earnest, I'll combine this thread back into the (newly rechristened) "pre-construction" thread.

For now, though, here's what DART about the construction schedule:
The 14-mile Orange Line is a key component of a regional rail expansion that will lead to the doubling of DART's rail network to more than 90 miles by 2013. The Orange Line will run parallel with the Green Line through Downtown Dallas to Bachman Station in Northwest Dallas. From Bachman Station, the Orange Line heads northwest to the Las Colinas Urban Center in 2011 and Dallas/Fort Worth International Airport in 2013.