Work on the Port Authority's light rail extension that has concentrated on boring twin tunnels under the Allegheny River will soon be more visible to passersby.

The board yesterday awarded two contracts totaling $89.7 million for construction to take place Downtown and on the North Shore that will soon put all 1.2 miles of the project under way.

A $49.9 million contract involves building the concrete-and-steel shell of a new Gateway Center Station in the grassy, triangular area across from One Fifth Avenue Place in the heart of the Golden Triangle.

A cut-and-cover excavation method will be used to build subway sections under Stanwix Street, connecting the new station to tracks at the existing Gateway Center Station at Liberty Avenue and to the new tunnels on the long block between Penn Avenue and Fort Duquesne Boulevard.

A $39.8 million contract involves building the elevated steel structures that will carry tracks parallel to Reedsdale Street, past Heinz Field to the end of the line. Related local road work and demolition of the old Miller Printing plant are also covered.

The nearly $90 million cost of the two contracts exceeds engineering estimates by about $29 million, an overage that authority Chief Executive Officer Steve Bland attributed to soaring concrete, energy and steel prices.

He said money for the two new contracts is available under the $435 million full funding agreement by which the Federal Transit Agency is paying for 80 percent of the North Shore Connector.

"We're still within budget although, for sure, we're dipping into our contingency fund" that provides a cushion of money for unanticipated changes, conditions and costs, Mr. Bland said. "[But] there are significant cost increases due to circumstances beyond our control."

Firms awarded Port Authority contracts yesterday expect to begin work this fall.

Also yesterday, the board approved paying up to an additional $3.5 million to DMJM Harris, the Pittsburgh firm providing architectural, engineering, design and support services for the North Shore Connector. The money will have increased its total maximum payments to $46.7 million since the initial agreement in April 2003.

Mr. Bland said while the $3.5 million exceeds the project budget for consultants, DMJM Harris did extra work, such as value engineering, to reduce overall project costs by $25 million to $30 million. As an example, he said closing Gateway Center Station while the new station is being built will simplify construction for the contractor and has therefore resulted in a lower bid.