Statue of Liberty park ranger Lance Williams looks out the windows inside the crown of the statue in this May 20, 2009, photo in New York. Next year, the statue will close for nine months to a year so workers can build a more up-to-date set of stairwells at Lady Liberty’s pedestal.

A journalist ascends the narrow spiral staircase to the crown inside the Statue of Liberty in New York in this May 20, 2009, photo.

New York ? A set of 354 narrow steps spirals all the way up to the Statue of Liberty’s crown, and it’s the only escape route for tourists in an emergency.

On a recent summer day, one tourist put his hands on his knees and gasped for air as a few others funneled down the tightly twisting staircase to the statue’s pedestal. They were covered in sweat.

“It was hot up there,” said Lucie Munier, visiting from France. “I think I would be scared in an emergency, but it is already pretty scary even when it is calm.”

When a smoke alarm tripped inside the statue last month, hundreds of tourists were rushed down the equivalent of about 15 flights of stairs in a matter of minutes — the same ones that firefighters would need to trudge up if the 125-year-old landmark catches fire.

National Park Service officials have closed the statue in recent years for a $20 million security upgrade, and kept the crown shut since the Sept. 11, 2001, terror attacks until last year to improve its fire safety. Next year, the statue will close again, for nine months to a year, so workers can build a more up-to-date set of stairwells at Lady Liberty’s pedestal, said National Parks Service spokesman Darren Boch.

“Given its age and the fact that it is a historic structure and there’s not much we can do to change it, it’s just not going to be 100 percent in line” with the most up-to-date safety standards, Boch said.

On Friday, the parks service will release an environmental assessment on the proposed changes and take public comment on the proposed alternatives through Sept. 13.

It is the first of several steps that the park is required to take before making changes of this proposed magnitude, and until the entire planning process is complete, it is not possible to accurately estimate construction costs, the parks department said.

Most tourists, 3,000 maximum per day, ascend the first 186 steps from the ground up to the pedestal. No more than 10 people at a time are allowed all the way up to the crown, in part so they can be quickly evacuated if necessary.

The scheduled improvements are expected to enable the park to increase visitation to the crown and improve visitor safety overall.

Though the statue was built in the 1800s before the days of modern fire codes, there isn’t much flammable material inside. Standing 22 stories high, it’s made from steel and copper as thick as two pennies put together. The staircases are metal. The massive pedestal is stone and concrete.

Elevators and electrical equipment that go up to the pedestal were built much later and are equipped with fire sensors like the faulty one that went off July 21; a faulty smoke head was blamed. There are sprinklers throughout the structure. A standpipe carries water to the top.

“For a structure of that age, it’s actually quite well equipped to deal with an emergency,” said Steve Ritea, a Fire Department of New York spokesman.

The statue is scheduled to close in October 2011, after its 125th anniversary for im-provements mainly in the pedestal. The newest fire codes mandate two separate ways down and air conditioning in at least one of the stairwells, and say the escape routes must enable the statue to be evacuated within two hours. The current staircases on either side of the pedestal don’t work. Right now, tourists go up one side and down another. One elevator is installed for tourists who can’t or don’t want to walk up; firefighters don’t use elevators in emergencies.