Costs. Construction projects in the U.S. are unbelievably expensive. The 2nd avenue subway is a perfect example. They dug 1.5 miles of tunnel and built 3 sta

Costs. Construction projects in the U.S. are unbelievably expensive. The 2nd avenue subway is a perfect example. They dug 1.5 miles of tunnel and built 3 stations for $4.5 billion. A fairly comparable project is the Berlin U5 extension. It also has 3 stops and about 1.5 miles of tunnel. It's being done for about $700 million. Lots of people would love to have new transit lines, new computer systems, etc, but the old ones were built when costs were affordable, and often can't be replaced for anything close to their original cost.