The Port Authority's latest estimate of the cost of the North Shore subway extension has dropped by $14 million, to $538.8 million.

Spokesman Jim Ritchie said the latest construction bids came in below estimates, and as the project advances, the authority has been able to trim the amount of money it has reserved for contingencies.

The project remains about $42 million short of funding needed for completion, but that is considerably less than the $117.8 million shortfall that existed at the start of the year, when officials feared they might have to halt the work.

The North Shore Connector will extend the Light Rail Transit system under the Allegheny River to new stations at PNC Park and Heinz Field. It is expected to open in 2011.

A Port Authority board committee today recommended awarding four more construction contracts totaling $28.4 million for finishing work to the two new stations and a new Gateway Center station, Downtown.