Cybele,
There's several types of rail, but you're combining two when you write "high speed light rail".
Heavy rail - 55-75 mph (MARTA in Atlanta)
Light rail 35-60 mph (Charlotte, Houston, Dallas)
High speed rail - 120-180 mph (other countries)
Just thought you should know the difference, because you can't possibly run HSR on rails designed for heavy or light rail transit.