Second Avenue Subway Construction

This photo shows an arch form used for tunnel concrete operations on the east tunnel of the Second Avenue Subway. (credit: Metropolitan Transportation Authority)

Second Avenue Subway Construction

Waterproofing of the east tunnel of the Second Avenue Subway. (credit: Metropolitan Transportation Authority)

Second Avenue Subway Construction

Building an entrance to the Second Avenue Subway's 72nd Street Station. (credit: Metropolitan Transportation Authority)

Second Avenue Subway Construction

Mining the cavern that will house the Second Avenue Subway's 72nd Street Station. (credit: Metropolitan Transportation Authority)

Second Avenue Subway Construction

(credit: Spencer Platt/Getty Images)

A Metropolitan Transportation Authority (MTA) worker walks in an underground tunnel for the long-proposed 2nd Avenue subway line on April 12, 2007.

Second Avenue Subway Construction

(credit: Spencer Platt/Getty Images)

A Metropolitan Transportation Authority (MTA) worker walks in an underground tunnel for the long-proposed 2nd Avenue subway line on April 12, 2007.

Second Avenue Subway Construction

(credit: Spencer Platt/Getty Images)

A Metropolitan Transportation Authority (MTA) worker walks in an underground tunnel for the long-proposed 2nd Avenue subway line on April 12, 2007.

Second Avenue Subway Construction

(credit: Spencer Platt/Getty Images)

Metropolitan Transportation Authority (MTA) workers look at proposed designs for a completed subway platform in an underground tunnel for the long-proposed 2nd Avenue subway line on April 12, 2007.

Second Avenue Subway Construction

(credit: Spencer Platt/Getty Images)

A Metropolitan Transportation Authority (MTA) worker walks in an underground tunnel for the long-proposed 2nd Avenue subway line on April 12, 2007.

Second Avenue Subway Construction

(credit: Spencer Platt/Getty Images)

A Metropolitan Transportaion Authority (MTA) worker sweeps stairs in an underground tunnel of the long-proposed 2nd Avenue subway line on April 12, 2007.

Second Avenue Subway Construction

(credit: Spencer Platt/Getty Images)

Metropolitan Transportaion Authority (MTA) manager Balbir Sood stands in an underground tunnel for the long-proposed 2nd Avenue subway line on April 12, 2007.

Second Avenue Subway Construction

(credit: Spencer Platt/Getty Images)

A Metropolitan Transportation Authority (MTA) worker stands beside proposed designs for a completed subway platform in an underground tunnel of the long-proposed 2nd Avenue subway line on April 12, 2007.

Second Avenue Subway Construction

(credit: Spencer Platt/Getty Images)

New York Gov. Eliot Spitzer speaks at a groundbreaking ceremony in an underground tunnel of the long-proposed 2nd Avenue subway line on April 12, 2007.

Second Avenue Subway Construction

(credit: Spencer Platt/Getty Images)

New York Gov. Eliot Spitzer emerges from an underground tunnel to the long-proposed 2nd Avenue subway line on April 12, 2007.