Drilling, pouring and the concrete-and-steel phase of Honolulu’s controversial rail project have finally arrived, and the start of heavy construction will be hard to miss.

In the years ahead, Leeward Oahu traffic will swirl — or stall — around a complex dance of drilling rigs, concrete pours, cranes and gantries that will be used to set segments of the guideway in place.

A key federal approval earlier this month cleared the way for this first segment of major construction for Honolulu’s 20-mile rail line, and contractor Kiewit Infrastructure West Co. will start work in March on the first 61⁄2 miles of elevated guideway for the rail system.

Much of that first phase from East Kapolei to Pearl Highlands will be easy to spot, because it will be built right down the median of Farrington Highway, which runs through Waipahu.

The first segment of the project also includes 30-foot-wide sections of guideway superstructure that will be erected more than 60 feet above the H-1 freeway near Leeward Community College.

The rail guideway will make a similar pass above the Fort Weaver Road-Farrington Highway interchange on the west side of Waipahu, and construction on the first rail stations on this portion of the guideway is scheduled to start late this year.

Kiewit has a $502 million contract to construct the first section of the guideway, and is scheduled to be finished in early 2015. However, work on other portions of the project will begin in phases so that construction is slated to continue along the rail route between now and 2019.

City officials warn that traffic delays are unavoidable, but say they will take extensive steps to avoid automotive havoc. Those measures include limiting lane closures to off-peak hours as much as possible, and doing night work in nonresidential areas.

The city has also committed to a "Maintenance of Traffic Plan" that spells out detailed parameters that Kiewit must follow, such as the number of lanes that can be closed and the traffic control measures that must be used at specific sites.

In the opening phases of construction along Farrington Highway, "the current plan is to always have at least one lane open in each direction," said Scott Ishikawa, spokesman for the Honolulu Authority for Rapid Transportation.

City officials say they have also designed the project itself to try to minimize the impact of rail on traffic flow and on the communities along the route.

Kiewit will construct "mono-shaft" foundations for the raised guideway, a design that avoids the noise, vibration and other problems associated with pile-driving. The project design also limits the need to take up lanes for the rail project, which helps to minimize the impact of the project on surrounding traffic flows, said Toru Hamayasu, acting executive director of HART.

Given the countinuing controversy over the $5.27 billion rail project, the launch of heavy construction could generate new support for the project, or could stir even more opposition.

Bob Loy, director of environmental programs for The Outdoor Circle, said hundreds of trees have been removed from the rail corridor, and are about to be replaced by a rail guideway that he described as "an inner-urban structure."

The Outdoor Circle announced last year that it opposes the rail project because of the impact on the Oahu landscape. Loy predicted rail will change the character of communities along the route.

"Waipahu will change from a former plantation town with low-rise buildings to a hard-core urban setting," Loy said. "Waipahu gets it first, but they are not going to be the last to experience it."

HART says the finished project will create badly needed construction jobs, and will provide commuters with a fast and reliable alternative to driving.

The city projects the rail system will improve highway travel times by taking about 40,000 vehicles off Honolulu roads each weekday by 2030.

The construction involves drilling shafts about 125 feet apart along the rail route, which will take place in the first segment mostly along highways or on highway medians.

Each hole or shaft will be 7 to 9 feet in diameter, and will be 40 to 120 feet deep. The final depth of each shaft will depend on soil conditions, said assistant project manager Lorenzo Garrido, HART’s assistant project officer for design-build contracts.

Workers will then lower cylinder-shaped reinforcing bar assemblies into the drilled shafts, and pour concrete to create the foundations for columns that will support the 30-foot-wide overhead rail guideways.

Once the below-ground concrete foundations have had time to harden, forms and rebar structures will be assembled above the poured foundations. Those forms will be used to create above-ground concrete columns 6 to 7 feet in diameter to support the raised guideway.

Most of the initial drilling and pouring will be done along the Kualakai Parkway (or North-South Road) and on the Farrington Highway median extending through Waipahu. Kiewit is also scheduled to erect columns in the median of Kamehameha Highway in the year ahead.

The guideway that will eventually sit atop those columns cannot be installed yet because Kiewit and the city still need federal permission to establish a precast facility where the sections of guideway can be fabricated.

Once that facility is up and running, concrete segments of guideway will be poured at that facility and trucked to the construction site.

For most of the project, the completed sections of guideway will be hoisted up on top of the columns by a crane, and assembled on a gantry or an erection truss atop the columns.

The sections of guideway are then fastened together with cable in much the same way that sections of the H-3 freeway were assembled, using large hydraulic jacks to tighten the cable and bind the segments together.

That design will vary in areas where the guideway passes over traffic intersections or the freeway.

In those areas, Kiewit will use structures called straddle bents or balanced cantilevers to construct the guideway over intersections or the highway. In some cases the sections of guideway will be poured in place, meaning they will be fabricated on top of the columns.

Commuters who travel in the Leeward corridor are bracing for construction delays, but at least some believe it will be worth it in the long run.

Dan D’Antin, vice president of the solar company Island Pacific Energy, said it is inevitable that members of the sales team from his company will get caught in construction traffic.

But D’Antin, 46, said the traffic should be bearable as long as the city communicates with the public to let people know what to expect, and as long as all lanes stay open during morning and evening rush hours.

"We’ll see what happens," said D’Antin, who supports the rail project. "I’m excited about it, and a lot of my contracting friends are excited about it.

"We’ve been waiting for a long time, and I think it will be welcome that finally we’re getting this thing going," he said. "I think there’s going to be more support than opposition, quite frankly."