Archaeological excavations along the planned rail route in Kalihi, downtown and Kaakako will prompt lane closures and detours — and might last from six to 10 months.

There are 232 planned dig sites across a 4.3-mile stretch for work that includes trenching into roads, which will likely get under way next month.

"We can get the results of the survey done prior to the commencement of final design," said Faith Miyamoto, chief planner at the Honolulu Authority for Rapid Transportation. "The point is, it’s being done years in advance of construction."

Oahu’s planned multibillion-dollar rail line will run 20 miles from East Kapolei, connect with Honolulu Airport and end at Ala Moana Center.

Each excavation site in the Kalihi-downtown-Kaakako corridor will take about four to seven days to clear. Trenches will be dug up in areas where the city plans to install the columns that will hold up the elevated guideway, as well as foundation areas for the 21 stations, and any area where utility relocation is necessary.

The trenches will be about 3 feet wide and 10 feet long for the guideway’s columns. Trenches for utility locations will be about 2 feet wide and 20 feet long. Crews will dig up to 10 feet deep.

The city will begin holding community meetings regarding the excavations today at Farrington High School. The Honolulu Authority for Rapid Transportation has also sent out about 21,000 postcards to affected residents and businesses along the stretch.

While the city said there will be lane closures and detours, it said residents will not see any road closures.

"We’re proactively working with both state and city traffic control centers to minimize any traffic disruptions," said Jeanne Mariani-Belding, spokeswoman for the rail agency. "We’re helping with signage if needed, trying to do work in commercial areas at night or in nonpeak hours, and making sure access to businesses remain clear."

Some of the excavations will take place inside buildings, even restaurants. For these cases the city will pay compensatory rent for any disruption of business, said Matt McDermott, project manager for Cultural Surveys Hawaii, which has been conducting surveys for the project.

"We will talk to the landowner or lessees and work out how we can get in there," he said. "We’ll work nights and weekends and try to impact them as little as possible. Some are businesses; some are parking lots, restaurants."

No burials were found in phases one and two of the 20-mile route, which runs from West Kapolei to Aloha Stadium, McDermott said.

An archaeological inventory survey plan is before the State Historic Preservation Division for approval.

"In this heavily developed urban environment, it’s obviously a good idea to do this plan first to establish what the scope of work is, where we’re going to look, how we’re going to do it," McDermott said. "The plan consists of detailed background research to figure out the old sediment patterns, the old land use of the area, trying to come up with a predictive model on where we expect to find archaeological deposits."

The background research includes Land Use Commission Awards from the 1850s, old historic maps and Native Hawaiian oral traditions and historic accounts.

Cultural Surveys Hawaii initially identified 212 dig sites in March, but after talking to residents and Native Hawaiian groups, 20 more were added. The groups criticized the city at the time for not adding more dig sites.

Although all road construction will be put on hold during the Asia-Pacific Economic Cooperation summit in November, city crews can still conduct archaeological surveys on private properties and use ground-penetrating radars to do preliminary work.

A field crew of eight to 14 archaeologists will be involved and will be headed up by McDermott and Cultural Surveys Hawaii President Hallett Hammatt.

If iwi kupuna, or ancestral bones, are found, a network of about 300 people will be notified, "far larger than any other project in the history of our time," said Lani Ma‘a Lapilio, cultural consultant for Aukahi, which will facilitate communication between the archaeologists and Native Hawaiians.

If remains are found during the survey process, a "treatment plan" on how to deal with the remains can be worked out with the descendants about three months after notification. The treatment plan could mean preserving the remains in place or relocating them.

The guideway’s columns can also be moved to avoid disturbing the grave sites, Miyamoto said. City engineers say the columns can be shifted 30 feet either way. Each column is about 8 feet in diameter.

"The whole intent of doing this is that in the event we do find something, there is the possibility for making adjustments to column locations," Miyamoto said. "It’s a balance between having plans that are pretty definitive and then yet being early enough so we can make the adjustments. We are sensitive to the concerns that you don’t want to disturb the burials."

The city has said that changing the alignment is also still a possibility, as well as a route change in the worst-case scenario.