July 15 appears to be the deadline for the Port Authority to finalize funding and award a contract to start a $393 million light-rail extension to the North Shore or forget about it.

The agency's board learned yesterday that the joint venture of West Mifflin-based Trumbull Corp. and Japan-based Obayashi Corp., low bidder at $156.5 million to bore twin tunnels under the Allegheny and do related work, has granted a 15-day extension to the agency to sign a contract.

"We asked for 30 days but [Trumbull-Obayashi] said they're having problems with suppliers and subcontractors about holding the line on prices," said Henry Nutbrown, authority engineering-construction manager.

The successful low bidder at the Feb. 2 bid opening was required to maintain its offer for 120 days. Although Trumbull-Obayashi has already granted a 30-day extension that expires June 30, it doesn't intend to bend again and wait longer than July 15.

If the authority does not line up the funds to pay for the contract, which is $21.5 million over engineering estimates, it would be forced to bid a third time -- unlikely inasmuch as bids have twice come in over budget and energy-driven construction costs continue to soar.

Authority officials are being tight-lipped about funding assurances for the project that would extend the line 1.2 miles north of Gateway Center and provide three stations. Latest cost estimates also are being kept secret.

The authority's new chief executive officer, Steve Bland, who started Monday, said, "There has been a fair amount of movement" in securing a full-funding agreement under which the Federal Transit Administration would pay 80 percent of the costs.

"Everybody is still optimistic, but the project has to go through a complex process."

If everything appears in order, the authority indicated it will hold a special meeting by the July 15 deadline and approve the contract, taking a chance that final procedural steps by federal, state and Allegheny County governments will fall in place so it can lock in the $156.5 million price and direct the contractor to begin utility relocation, preliminary work and staging by late summer.

Mr. Nutbrown said North Shore developers are "excited" about the light-rail extension and "ready to move forward with other projects." Two office buildings, a hotel and parking garage already have been built on property around PNC Park and Heinz Field.

The Trumbull-Obayashi contract would cover about half of the civil work needed to build the extension north of Gateway Center station, Downtown. Besides boring twin tunnels under the Allegheny, its work would include constructing 1,200 feet of cut-and-cover tunnel along the western side of PNC Park and the shell of an underground station there.

A new Gateway Station would be built, providing both inbound and outbound platforms instead of the single platform at the present station.

The other North Shore station would be elevated, above Allegheny Avenue and Reedsdale Street and linked to the new parking garage that's about to open.

The county's share of the project would be about $13 million. The state would pay a 20 percent share.