The Maine Department of Transportation began advertising Wednesday for contractors for the first phase of a major highway bridge project in Portland.

The Million Dollar Bridge, a bascule structure that opens for the passage of ships through the city’s harbor, will be replaced by a bridge more suited to the needs of the 21st century.

Larry Roberts, a DOT project design engineer, said Wednesday that the project will cost $165 million, a far cry from the $975,000 bill for the existing structure completed about 1915.

Passage of Question 3 in the state referendum in November, which would authorize borrowing $39,500,000 for highway, bridge and other transportation improvements, will benefit final phases of the Portland-South Portland bridge project, Roberts said. Most of the bridge construction is being funded through the Federal Highway Demonstration Project, a part of the Intermodal Surface Transportation Efficiency Act (ISTEA). By law the federal government provides 80 percent of the project’s cost. The remainder comes from state coffers.

If Maine voters approve Question 3, the state will be eligible for up to $125 million in matching federal funds. Many projects are envisioned, including a $2.9 million deck replacement on the Joshua Chamberlain bridge linking Bangor and Brewer.

Even as state transportation planners prepared to issue a series of contracts to build the replacement for the 78-year-old Million Dollar Bridge in Portland harbor, pieces of crumbling concrete fell off the abandoned Beach Street approach in Portland. The approach was closed several years ago.

At several spots metal beams shore up the concrete supports on the main bridge approach.

Roberts said bids for the contract for construction of the bascule substructure for the section that will open for ships will be reviewed Dec. 7. Later in December, bids will be opened for reconstruction of streets in South Portland leading to a new approach to the harbor crossing from that city.

A call for bids for two more phases of the project — construction of the bridge superstructure — will be issued in the fall of 1995, Roberts said. The last contract, to be issued in 1996 or 1997, will call for demolition of tons of steel and concrete in the existing bridge.

The DOT engineer said the project’s cost includes engineering and right-of-way acquisition fees. The new bridge will be built parallel to the existing structure from the Portland approach to midchannel. There it will cross above the Million Dollar Bridge and enter South Portland from a different angle along the side of the bay.

“We expect there will be very little disruption of traffic crossing the harbor,” he said. Highway traffic will be shifted from one bridge to the other as construction progresses.

The existing draw that opens for ship traffic folds up in two sections. The new bridge will feature four “leaves” that fold in a similar manner, Roberts said. Ships must pass through the bridge opening to reach oil and general commerce terminals in the inner harbor. One, the Roc Sea, from the Republic of Vanuatu, steamed up to Merrill Marine Terminal recently to take on a load of scrap metal. Small tankers regularly use the inner harbor to dock and discharge petroleum for a nearby tank farm.

The bridge carries Route 77 traffic between Portland and the communities of South Portland and Cape Elizabeth and is considered a major commuter artery in the area.