The new station, at 34th Street and 11th Avenue, isn't scheduled to open to the public until next fall. But it was operational enough that Bloomberg was able to take a No. 7 train to the new platform Friday from Times Square.
Workers built the $2.4 billion station to serve a forest of skyscrapers under construction near the Hudson River.
The city paid for much of the project.
Bloomberg said the station came in basically on time and on budget and is something to be proud of.
Construction on the No. 7 line extension began in 2007.
