SAN DIEGO - Airport authority officials released an environmental study for the second time Monday on $650 million worth of proposed Lindbergh Field improvements, including 10 new airline gates and more space to pick up and drop off passengers.

San Diego County Regional Airport Authority officials said the improvements included in their master plan probably would not be built until 2012 and would ease traffic for a few years.

The authority says Lindbergh, the county's only regional commercial airport, badly needs the improvements to handle increased traffic.

Lindbergh handled 17.5 million passengers this year, but the authority expects that number to climb to 22 million by 2015 and 27 million by 2030.

Keith Wilschetz, the authority's director of airport planning, said the new airline gates were key to the short-term improvements.

"The primary feature is, we need to add 10 new gates at Lindbergh, and we plan to do it at terminal two," he said.

Wilschetz said the new improvements would probably provide only temporary relief - through 2015 - and that new plans, including the possible construction of another airport runway, would need to be considered in the future.

"With these new gates, we'll have 51 total," Wilschetz said. "Our best analysis is that the runway can sustain about 60 gates. At some point we will probably look to build additional gates. (But) once we reach that point, it wouldn't make a lot of sense to add more gates because the runway will simply be at its maximum."

But he also said that the authority did not have the luxury of waiting and trying to come up with a long-term fix because the airport was already overcrowded and needed immediate help. Wilschetz said the airport already needed 43 gates and only had 41, and that the strain would only grow.

"Given the fact we're already behind we want to get these gates in place," he said. "And in 2015, then, certainly, it will be time to look at something else."

Wilschetz said the other key short-term improvements that could be built once the environmental study was certified included:

n A two-level roadway and curbside at the expanded second terminal that would allow more people to pick up and drop off passengers while simultaneously reducing the current crowded conditions. Wilschetz said the roadway would be similar to those seen at Los Angeles International and other major airports.

n New, safer aircraft parking and overnight aircraft parking on the current airfield so that airplanes would not have to cross over Lindbergh's single runway to get to the existing parking spaces.

n New hangars and facilities for private aircraft.

The airport authority, which was created five years ago primarily to locate a new site for a regional airport, came under heavy fire in 2006 when voters overwhelmingly rejected the authority's choice of Miramar Marine Corps Air Station. Since then, the authority has said its goal was to make Lindbergh "the very best it can be."

Wilschetz said the authority plans to begin work on a plan to address Lindbergh's long-term questions in the fall.

Wilschetz said the current master plan studied in the environmental document included two separate types of plans. The first were short-term improvements such as new airline gates. The second piece of the report revolved around longer-term projects that would need further study at the 661-acre airport - including a possible transit center where people could come to the airport by bus and even rail.

Wilschetz said the agency hoped to hold public hearings and gather comments on the environmental study until Nov. 30, and to issue a final plan for authority board members to approve in March or April.

Authority spokeswoman Diana Lucero said the authority planned to hold seven, eight-hour hearings for the public to comment, including one from noon to 8 p.m. Oct. 23 at Carlsbad's Harding Community Center.

Meanwhile, airport planner Ted Anasis said the environmental study reported that the Lindbergh improvements would create traffic problems in the areas around Lindbergh that could be eased by building new lanes and turn lanes. However, Anasis said, the steadily-increasing traffic would eventually create air pollution problems that could not be eased.

Monday marked the second go-round for the environmental study.

Agency managers released a draft plan in May 2006. But the authority's board asked that it be redone with two major changes. First, the board wanted an alternative that did not include a proposed four-story parking garage.

Second, the board asked that managers include a possible transit center in the long-range portion of the plan.

People interested in seeing a copy of, or commenting on, the environmental study, or to get more information, can go to www.sanplan.com.

- Contact staff writer Gig Conaughton at (760) 739-6696 or gconaughton@nctimes.com.