State lawmakers pressed developers of the Hawai'i Superferry yesterday to provide data on the impact of ferry service on traffic around harbors as they weigh whether to cut state money they approved last session for harbor improvements.

John Garibaldi, chief executive officer of Hawai'i Superferry, said traffic studies were on track to be completed and turned over to the state Department of Transportation in June but that he would try to have something for lawmakers before the end of the session early next month.

Garibaldi appeared at an informational briefing at the state Capitol to update lawmakers on the ferry and answer questions. The state Legislature granted $40 million last session for state harbor improvements to help the ferry but the state Senate has temporarily removed $10 million because some senators are concerned that the company has not adequately explained its plans to communities.

The state House and Senate could put the money back in the state budget during conference committee if lawmakers are satisfied that the company will be responsive to community concerns.

Lawmakers want to know whether the company plans to share with the state and the counties any additional costs for traffic improvements near the harbors. They also want to hear whether ferry service will conflict with existing harbor users, especially on the Neighbor Islands.

Hawai'i Superferry is scheduled to begin passenger and vehicle service between Honolulu and Kahului, on Maui, and Nawiliwili, on Kaua'i, in 2007. A second ferry is expected to run between Honolulu and Kawaihae, on the Big Island, in 2009.

Garibaldi detailed the community outreach efforts by the company, including new advisory boards on Maui, Kaua'i and the Big Island that will respond to local issues. The developers also have plans to help prevent the spread of invasive plant or animal species and minimize encounters with whales by altering routes to Maui and the Big Island during whale season.

Garibaldi told lawmakers the company will likely have to re-examine its plans if any of the $40 million in harbor improvements is cut. He said the company has lost money during the planning stages and would likely continue to lose money until ferry service begins. He predicted the ferry would turn a profit within the first year of service.

"Quite frankly, anything short of the $40 million would have a very negative effect on us," Garibaldi said.

After the briefing, lawmakers said they generally support the ferry but want more information.

"I think it's important for residents to understand what they're getting for their $40 million," said state Sen. Shan Tsutsui, D-4th (Kahului).

State Rep. Joe Souki, D-8th (Wailuku, Waiehu), chairman of the House Transportation Committee, said he favors the ferry but wants to hear how roads around Kahului harbor that are already busy with traffic will handle more activity.

"I just would like to see what kind of potential problems, if any" would be caused by the ferry, he said.

Reach Derrick DePledge at ddepledge@honoluluadvertiser.com.