The state Department of Transportation has conditionally endorsed the proposed Ho’opili development with 11,750 homes in Ewa — reversing a previous position — in part because project developer D.R. Horton agreed to widen a stretch of H-1 Freeway.

The widening, which would add one lane in each direction between the Kunia and Waiawa interchanges, was a major reason why DOT decided to support Ho’opili, according to Alvin Takeshita, the agency’s highway division administrator.

"I think the benefit is tremendous," he said, explaining that adding two lanes to the present 10 lanes represents a 20 percent capacity gain.

Takeshita communicated the department’s position in testimony Thursday during a hearing of the state Land Use Commission, which is considering whether to convert 1,554 acres of prime farmland for development of the estimated $4.6 billion community with roughly as many homes as Mililani or Hawaii Kai — plus five public schools and 3 million to 4 million square feet of commercial space.

During a previous round of hearings in 2009, DOT said occupancy of any building at Ho’opili should be prohibited until H-1 and other surrounding roads operate at an acceptable level defined as at least a "D" rating on a scale of A to F with F being gridlock.

Three years ago, DOT concluded that even with the most optimistic rail projections, the best freeway rating with Ho’opili would be E, and that the local Schuler Division of Texas-based Horton had no reasonable proposal to resolve regional traffic concerns.

DOT is the third state agency to reverse its position on Ho’opili since Horton’s petition was rejected three years ago because the developer didn’t divide the project in phases as required by state land-use law.

The state Department of Agriculture had objected to the loss of prime farmland, and the state Office of Planning had raised concerns over the phasing issue and positions of the two other agencies.

Since then, the developer made changes to its plan affecting traffic and the loss of farmland, and reapplied for approval from the commission last year.

In testimony earlier this month, the Agriculture Department switched its position based on Horton’s plan to retain 251 acres for farming at Ho’opili, including 159 acres for commercial farms, 84 acres of home gardens and eight acres of community gardens while ending existing farming gradually over 20 years.

The Office of Planning endorsed Ho’opili on Thursday, largely based on the positions of the other two departments and because the site is within the city’s urban growth boundary and near other urban projects including the University of Hawaii-West Oahu, the Salvation Army Kroc Center and Department of Hawaiian Home Lands homes.

However, Ho’opili opponents including community group Friends of Makakilo and the Sierra Club Hawaii Chapter say Horton’s changes don’t make the project acceptable.

Friends of Makakilo leader Kioni Dudley questioned Takeshita as to how widening part of H-1 would ease traffic when the widening ends before lanes merge with H-2 and traffic from Mililani and the North Shore.

Dudley said the widening would just worsen rush-hour bottlenecks at the H-1/H-2 merge, and suggested that no widening there is possible.

Takeshita didn’t accept Dudley’s view that it’s impossible to widen H-1 where it merges with H-2, but he didn’t say there is any plan to do so.

However, Takeshita said other planned improvements should help mitigate increased traffic from Ho’opili. Those improvements include an afternoon H-1 contraflow lane, which is slated to start construction next year, and widening H-1 along its most congested segment between Punahou and Middle streets, which is intended to be completed by 2014. Improvements to the west-bound Waipahu off-ramp is another project.

Typically, developers of large communities pay a "fair share" of regional traffic improvements because of impacts from their projects. Horton agreed to pay for all of the Kunia-to-Waiawa interchange widening of H-1 that Takeshita roughly estimated might cost around $10 million.

Eric Seitz, an attorney representing Sen. Clayton Hee, who along with Dudley’s group and the Sierra Club is challenging Ho’opili before the commission, asked Takeshita how residents can believe the planned traffic improvements will be sufficient when the commute on H-1 takes longer than it did five, 10 or 15 years ago.

"Hasn’t it been a losing battle?" Seitz asked, indicating that urban development has been allowed to grow faster than freeway capacity.

Takeshita disagreed that DOT is losing such a battle, but acknowledged that congestion remains a serious problem. "We have not solved 100 percent of the problem," he said.

The DOT is endorsing Ho’opili with conditions that include Horton making a binding commitment to the traffic improvements before any zoning change is approved. Another condition is updating a traffic impact analysis report with more recent data subject to agency review and approval.

However, DOT is suggesting that it would be fine to satisfy the conditions before any zoning change, which is a decision that would come after a Land Use Commission decision.

Seitz suggested that the commission should be able assess an updated traffic study before it decides whether to approve the project.

The commission, which has heard testimony on Horton’s revised plan since October, is expected to make a decision later this year after more hearings that will include expert witnesses for project opponents.

The next hearing dates are tentatively March 1 and 2.