The study to expand the Gov. Thomas Johnson Memorial Bridge over the Patuxent River is nearly finished. State officials say they can build either an additional span next to the existing one, or tear down the span and build a larger bridge.

St. Mary’s County officials said late last month that, either way, they want the new bridge to be tall enough to allow large ships to pass beneath it — as the existing span does — to take potential economic advantage of a deep-water port just north of the bridge that once was used by the U.S. Navy.

Several Calvert County officials said they would like to see the state build a new bridge, which residents told officials they wanted in a series of public hearings in the fall.

In any case, the project, estimated at $750 million, is still years from completion and far from fully funded, according to Maryland State Highway Administration officials, who briefed the St. Mary’s County commissioners on June 28 on the status of the plan and asked for the board’s preferences on options to expand the bridge, which carries traffic in one lane in each direction, and to smooth the flow of traffic at the intersection of Route 235 and Route 4, just west of the bridge.

The intersection has failing levels of service in the morning and afternoon, resulting in bottlenecks and car queues that don’t empty on a green light.

The state has allocated $5.5 million to plan the project, said Jeremy Beck, an SHA project manager. He said that the other phases of the project, including its final design, right-of-way acquisition and construction, have not yet been funded. Because it is a state project, the counties are not expected to pay any of the costs.

One option is building a new, second span parallel to the existing bridge. Under that scenario, the existing span would carry two lanes of traffic southbound, while a new span would carry two lanes northbound with an additional 10-foot lane for pedestrians and bicyclists.

The other option is building a new bridge with four lanes for vehicles and a lane for pedestrians and cyclists, and tearing down the existing one. A new span would be 7,310 feet long, Beck said, about the same length as the current 1.5-mile bridge.

State officials have said that the earliest the project can be completed is 2020.

The St. Mary’s commissioners had no unified opinion two weeks ago on which option they preferred, but, in later interviews, three out of five said that any new span should be tall enough to allow large ships to move beneath it.

The bridge opened in December 1977 and cost $26 million. At its highest point, the span is 140 feet above the river’s channel, which is 130 feet deep. The U.S. Navy wanted the bridge built at that height to allow its ships to pass beneath the bridge and anchor at the Patuxent River Naval Air base’s Solomons annex, north of the bridge.

The Navy no longer moors ships at the pier, which burned down a few years ago, though the area remains a deep-water port. A commercial port was proposed in the 1970s, at today’s Myrtle Point Park in California, across the river from the Navy pier.

Beck said federal officials are comfortable with any new bridge at least 70 feet tall.

“Lowering the bridge would potentially reduce costs,” he said. “They do not need that height anymore,” he said of the Navy. He said that he could not specify at this point how much less it would cost to build the lower bridge.

“We have that deep-water channel there,” said Todd Morgan (R), St. Mary’s county commissioner, on June 29. “You don’t want to ruin opportunity economically on either side of the bridge.”

St. Mary’s commissioners’ President Jack Russell and Commissioner Larry Jarboe agreed.

“We probably need to keep the height as it is for the Solomons annex,” Jarboe (R) said June 29. “It would be a logical place in the future with federal support for cruise ships running out of Solomons.”

“If you’re going to spend a billion­-dollars-plus, why shortchange yourself?” Russell (D) said. “I think we ought to put a bridge back that will replicate the one we have now.”

Calvert County commissioners’ President Susan Shaw (R) said she thinks the best approach is to marry what the public has said it wants to see — a new four-lane bridge with wide shoulders — and SHA’s studies, because state Sen. Roy P. Dyson (D-Calvert, Charles, St. Mary’s) has said the current span is unsafe due to the traffic it bears. State highway officials have said that the bridge is safe, though not adequate, to carry its current traffic load.

“At the time it was built, I don’t think we could have foreseen the amount of people that use it today,” Shaw said. Many of Calvert’s commuters use the bridge to get to work at the naval base.

“We need a new bridge,” Shaw said. “It’s just not even debatable.”

The height makes it a stunning visual landmark, she said, despite the fact that the height no longer is required by the Navy.

“So then it comes down to the fact that it is a lot more expensive to build a new bridge at the same height as the old bridge, versus the additional justification of it being a stunning visual marker,” she said. “That’s the kind of thinking that should be going on.”

Calvert Commissioner Gerald W. “Jerry” Clark (R) said he believes, based on public hearings SHA conducted in the fall, that the option that residents have most embraced is the construction of a new bridge, with additional space for bikers and pedestrians.

“One thing I didn’t want to see is one bridge parallel beside it, so you have one higher and one lower,” Clark said of the possibility of building a second span.

“It could be much, much lower,” Commissioner Evan K. Slaughenhoupt Jr. (R) said. “But I also understand there is currently a nice view of Solomons when you’re up there. The lower you go, the lesser the nice view.”

Slaughenhoupt said Solomons residents have expressed the same concern over building a second span. “If they build another span and the existing one remains, it should stay at the same height, otherwise it’ll look ugly,” he said.

The SHA will produce its preferred bridge alternatives this fall, and the location and design approval is scheduled for next spring, Beck said.

Three options exist for the rebuilding of the intersection of routes 235 and 4, the busiest intersection in St. Mary’s County, which sees between 40,000 and 55,000 vehicles a day.

One option allows a constant flow of traffic; another would build a ramp from Route 4 to southbound Route 235; a third would build an intersection in which Route 4 would cross beneath Route 235.