Lawrence motorists in search of free, long-term parking downtown soon will need to reset their compasses.

City commissioners at their Tuesday evening meeting will consider a proposal to eliminate the free, 10-hour parking on the roof level of the city’s garage in the 900 block of New Hampshire Street. But commissioners also will consider at least temporarily allowing free parking on the roof level of the new Vermont Street garage being built next to the expanded Lawrence Public Library.

The shift is part of the city’s efforts to formally open the 324-space, $5.2 million Vermont garage. The city has been allowing motorists to park in the garage for the past few months, but commissioners haven’t set rates for the garage or installed equipment to collect fees.

That soon will change. City Manager David Corliss is recommending a system similar to what is used in the New Hampshire Street garage. The proposal includes:

• Free parking spaces on the first level and the northern end of the second level of the garage;

• Long-term parking at the rate of $1 per 10 hours on the rest of the second level and all of the third level.

• Free, 10-hour parking on the uncovered roof level.

Motorists will have to exit their cars and use a self-service pay station. Corliss said the city studied a gated system similar to what Kansas University uses but cost estimates came in about $200,000 more than the pay station system.

The pay stations won’t be equipped to accept credit cards, although they will be wired so that feature could be added later. Corliss said costs, especially the service fees charged by credit card companies, made that option unfeasible.

“One of the challenges we have is that with the relatively modest amount we charge for parking, it is difficult to generate the type of revenue needed to justify those capital costs,” Corliss said.

Corliss said he opted not to use the opening of the garage as a reason to seek an increase in parking fees, but the issue will have to be addressed at some point as personnel and maintenance costs continue to rise.

The city’s parking fund generates about $1.2 million a year, but most of it comes from the money deposited into Massachusetts Street parking meters and fines charged for overtime parking. The money generated by the New Hampshire Street parking garage was less than $9,700 in 2012, according to the city’s budget.

“The garages do create expenses for us,” Corliss said. “We have to clean it, monitor it, pay the electricity, and just do general maintenance.”

Corliss said he is recommending eliminating the free long-term parking on the roof of the New Hampshire garage because it’s becoming heavily used as more development occurs in that area.

“We don’t need to provide an incentive for people to park there anymore,” Corliss said.

He said he is recommending free parking for the roof level of the Vermont garage at least while the library is under construction, which is expected to be into the summer. He said he might re-evaluate the free rooftop parking once the library project is open and the nearby Lawrence Outdoor Aquatics Center opens for the season.

“I think it is going to be a busy garage,” Corliss said.

Commissioners meet at 6:35 p.m. on Tuesday at City Hall.