KAHULUI, Maui — Opponents of the Hawai'i Superferry are planning a roadside demonstration this week to coincide with state Department of Transportation meetings on planned harbor improvements to accommodate the new interisland service, which is scheduled to begin next year.

Members of Save Kahului Harbor, the Sierra Club and other groups will wave signs along Ka'ahumanu Avenue in Kahului from 4 to 5:30 p.m. Wednesday urging Gov. Linda Lingle to delay ferry operations until potential impacts are studied.

Various groups have raised concerns about increased traffic, overcrowded harbor facilities, conflicts with canoe paddling activities, collisions with humpback whales, and the introduction of invasive plant and animal species.

Last week, shipbuilder Austal USA installed four 49-ton engines in the first Hawai'i Superferry vessel under construction at a shipyard in Mobile, Ala. That ferry will be used to launch daily service between O'ahu, Maui and Kaua'i in July 2007. A second vessel will be built to provide Big Island service in 2009.

The four-deck ferries will be able to carry more than 850 people and 250 cars, trucks and buses. The company has said that it will inspect the vehicles and take other measures to prevent the spread of invasive species. It also said it is developing a plan to avert contact with whales.

The DOT public meetings will present information and allow the public to comment on the planned barges and vehicle ramp systems for the ferry at Honolulu, Kawaihae, and Nawiliwili harbors. Hawai'i Superferry officials also will be on hand.

Big Island meetings will be held at 7 p.m. tomorrow at Konawaena High School, 10 a.m. Tuesday at Thelma Parker Memorial Public and School Library, and 7 p.m. Tuesday at the Hilo State Office Building.

The Maui meetings will be at 7 p.m. Wednesday at the Lahaina Civic Center, 10 a.m. Thursday at the Old Kalama Park Pavilion in Kihei, and 7 p.m. Thursday at Lihikai Elementary School.

On Kaua'i, the meetings will be at 7 p.m. June 26 at Kapa'a Middle School, 10 a.m. June 27 at 'Ele'ele Elementary School and 7 p.m. June 27 at Wilcox Elementary School.

O'ahu meetings will be at 7 p.m. June 29 at Pu'uhale Elementary School, 7 p.m. July 5 at Ali'iolani Elementary School, and 7 p.m. July 6 at Kane'ohe Elementary School.

For special accommodations, call Marshall Ando at 587-1961.