I was reading about the Washington, D.C. streetcar line that is being constructed and was pretty shocked by its projected cost: $3 billion dollars. Detroit's streetcar line is projected to cost $137 million dollars, less than 5% the cost of D.C.'s, and will stretch a over a mile longer than D.C's line [[3.3 miles vs 2.2 miles). Is anybody aware of why these two projects differ so dramatically in cost?

For reference: http://www.washingtonpost.com/local/...b89_story.html