PORTLAND — New rooms and a helipad on the East Tower of Maine Medical Center will improve delivery of care, but the most immediate impact from the hospital’s upcoming $512 million expansion will come at street level.

Beginning next month, Congress Street between Forest and Weymouth streets will be closed for an estimated eight weeks, while prefabricated concrete sections will be installed on two floors of the MMC visitors garage.

In addition, construction on the East Tower will require closing Wescott Street between Crescent and Ellsworth streets for a year, according to a hospital press release.

Motorists should also expect lane closures and traffic delays on State Street for the next two months. Installation of new stormwater and wastewater pipes and drains, and associated utility work, began last summer and is scheduled to wrap up this spring.

The Portland Planning Board approved plans for the first phase of the hospital expansion March 27.

MMC spokesman Matt Wickenheiser on Monday said that while some visitor parking will be diverted to a garage on Forest Street, behind the Maine Medical Partners offices at 887 Congress St., the visitors garage will not be closed entirely.

Instead, employees and visitors will use a Gilman Street entrance to what is now an employee garage.

“The two garages are connected internally, and we are reworking the Gilman Street entrance and exit to allow both patient/visitor and employee access,” Wickenheiser said.

Patients and visitors will then pass through employee parking areas, although the two upper levels of the visitors garage will be closed. That means at least 150 spaces will be lost during construction.

The garage expansion is expected to be completed in the fall, and will ultimately add 225 spaces.

The Congress Street detour will take traffic along St. John Street to Park Avenue, Weymouth Street and back to Congress Street.

The Congress Street closure comes as contractors finish work on State Street between Park and Cumberland avenues that began last August.

City spokeswoman Jessica Grondin on March 30  said the State Street work would resume this week, with contractors working from 7 a.m.-7 p.m. on sidewalk improvements, curbing, signal and crosswalk improvements and final paving. New storm drains and other utilities were installed before a winter hiatus.

Grondin initially said the work was supposed to conclude around the end of May, but it could be done sooner.

“We are working with the contractor to do everything possible to have it completed by the time Maine Medical Center begins their construction work and closes Congress Street,” she said in a press release.

The contract with the city requires completion of all work by June 30.

A third project is also underway on the peninsula, to separate stormwater and wastewater mains in the area of Washington Avenue, and Walnut, North and Madison streets.

Grondin said the working hours to install new mains to reduce wastewater flow to Back Cove are 7 a.m.-7 p.m. Washington Avenue will remain open, but there will be lane closures and traffic delays.

There will be parking restrictions on Washington Avenue and Walnut Street will be closed to all but local traffic in July, but the City is working with contractor to limit work on Washington Avenue to a minimum between July 4 and Labor Day, Grondin said.

David Harry can be reached at 781-3661 ext. 110 or dharry@theforecaster.net. Follow him on Twitter: @DavidHarry8.

Expansion of the Maine Medical Center visitors garage on Congress Street in Portland will require closing a section of the street for an estimated eight weeks, beginning in May.

Maine Medical Center provided this map of detours while Congress Street in Portland is closed between Forest and Weymouth streets because of hospital construction.