2004 numbers were $2 million/mile for single track and $2.5 million/mile for double track.

Labor is a significant component. Cheap electrification can be done with wooden poles (Ed Tennyson used 18" diameter treated poles that may still be in service for SEPTA).

Typically the carrier wire is stranded aluminum & steel (Al for conductivity and Fe for strength) and only the contact wire is copper (a very low % silver alloy# is preferred for wear resistance and additional mechanical strength). Other train trolley wire designs are in common use as well.

# Measured in troy ounces of silver per ton. 1 troy ounce has exactly the same electrical properties as pure copper, but improved physical properties. From distance memory I liked 3 or 4 troy ounces of silver per ton.

Best Hopes,

Alan