How Much Does It Cost to Build a New Subway Line?

A new subway line can cost anywhere from several million US Dollars (USD) to several billion dollars, depending on where the line is being built, how long it is and the labor costs involved. When completed, the Second Avenue subway line in New York will be the most expensive subway in the world, costing about $2 billion USD per mile (1.6 km) and more than $17 billion USD total. By comparison, London's Jubilee line cost about $560 million USD per mile (1.6 km); Singapore's Circle Line cost about $208 million USD per mile (1.6 km); and Madrid's Metrosur line — which is almost five times longer than the Second Avenue subway line — cost about $92.8 million USD per mile (1.6 km).

More facts about subway lines:

• The location of a subway line can really affect the cost of building it. One of the reasons the Second Avenue line is so expensive is because of the expense of Manhattan property. Other reasons include elevated labor costs and expensive design and construction plans.


• Another factor in how much a subway or metro line costs is how old the existing transit line is. Lines in cities such as New York and Chicago, where subway services have been in operation since the 1800s, are much more expensive to upgrade than other, newer lines.


• The Second Avenue subway line has been planned and built on and off since 1936.