Port Authority Chief Executive Officer Steve Bland says not finishing the 1.2-mile light-rail extension to the North Shore "is not a viable option."

Cost overruns on the $435-million project have not yet reached a crisis point, he told members of the Pittsburgh Post-Gazette editorial board in a meeting yesterday.

Mr. Bland's comments came in the wake of a $48.9 million apparent low bid on Tuesday for the second contract on the project -- building the concrete and steel shell of a new Gateway Center Station Downtown. The bid was well beyond the $25 million-$30 million range of engineering estimates. That will leave the authority with $147 million of uncommitted funds for the final four contracts.

The discussion of project costs also came on the same day that the Port Authority announced its expensive German boring machine will be shut down for up to six weeks.

The machine, which is sitting about 10 feet away from the edge of the Allegheny River underneath the North Shore, has been stalled because pipes that carry the excavated soil out of the tunnel have become clogged, said Winston Simmonds, the authority's rail operations engineering officer.

Contractors are in the process of shoring up the soil in front of the machine with concrete grouting before entering the machine's excavation chamber to find out what has caused the blockage, he said.

The delay may push back the drilling schedule by a couple weeks at most, he said, because the machine had been moving at a faster pace than original estimates. He did not know whether it would add any additional costs to the project's total.

The authority's $147 million in uncommitted funds includes about $18 million remaining in a fund for unforeseen circumstances and cost overruns.

Mr. Bland said the authority would have a better grasp of the situation after May 14, when bids are to be opened on another major component -- building the shell of Allegheny Station on the North Shore plus the structure for an elevated stretch of the line northwest of PNC Park.

"The expenditures stretch out through 2011, so we have time," Mr. Bland said. "We're concerned but not surprised because we're seeing this type of cost escalation across the country."

Mr. Bland said such soaring costs do not bode well for future expansion projects.

"This seriously delays looking at the next major plan," like extending light-rail to Oakland, an idea suggested by county Chief Executive Dan Onorato and a transportation task force he has assembled.

The tunnel boring machine uses a clay and water slurry to pressurize and soften the earth as it moves forward, and it was the pipes that carry the slurry and excavated material back toward the North Shore that became clogged starting a week ago.

Mr. Simmonds said workers noticed pieces of wood coming back through the pipes, so one theory is that the machine hit wooden fill material in the riverbank.

The machine will bore parallel tunnels beneath the river to carry trains back and forth between Downtown and the North Shore. That work is part of the initial, $156.5 million contract, which is 40 percent completed.

On other subjects discussed with Post-Gazette editors, Mr. Bland said:

• The authority is finalizing a marketing plan to sell naming rights for the North Shore Connector, saying there's precedent in the transit industry. For example, Cleveland Clinic has purchased the naming rights for a new bus rapid transit facility in Cleveland.

• By fall, the authority will take the first step toward a "smart card" fare collection and tracking system by soliciting bids for hardware for the estimated $30 million-$35 million project. The high-tech system would be 80 percent federally funded.

• By the end of the month, the treasury department will be caught up with processing and depositing barrels of money that had gone uncounted because of personnel shortages. Nearly $1 million had been sitting in the barrels, a situation that brought criticism when disclosed in February.