Ever since former Mayor Mufi Hannemann resurrected the idea of a Honolulu rail transit line in 2004, supporters and opponents of the project have sparred over the issue of how many jobs would be created during the construction phase of the $5.17 billion project.

Various groups have used different metrics to come up with a range of estimates — from 5,000 to 17,270 — for job creation in the peak years of construction. Opponents of the project have routinely dismissed the higher estimates as overly optimistic.

The most widely circulated projections of rail jobs come from the city’s environmental impact statement for the rail project, the University of Hawaii Economic Research Organization and the Pacific Resource Partnership, which represents construction companies in Hawaii and the local carpenters union.

Although there is considerable variation among the three estimates, there is a general agreement that the rail project will provide a major boost to the state’s struggling construction sector, which has been losing jobs since peaking four years ago.

Even UHERO, which had the lowest estimate of the job creation among the three, was bullish on the potential impact of the rail project in a forecast.

"Assuming no additional delays, the rail project will lead to a sharp pick-up in construction beginning later this year (2011) and the construction job base will approach its 2007 peak level by 2015," the UH economists wrote in the February report.

The amount of spending budgeted for the rail project translates into 5,000 to 5,500 construction jobs at the peak of activity in 2013 and 2014, according to an economic model developed by UHERO.

The EIS, which contained the highest job estimates, included construction jobs and "induced" jobs that would be created from consumer spending by construction workers. The EIS, using job multipliers developed by the U.S. Bureau of Economic analysis, estimates the rail project will boost total employment across Oahu’s economy by an average of 8,100 positions in each of the 10 years. The EIS time line plots job creation on a bell curve, with the employment peaking at 17,270 positions in 2013 and 15,020 in 2014.

The city’s Rapid Transit Division, using figures adapted from the EIS, has been quoting a figure of about 10,000 jobs a year in its press releases and marketing materials. The bulk of the construction will take place between 2011 and mid-2018, a period of 71⁄2 years, said Scott Ishikawa, spokesman for the Rapid Transit Division. The EIS estimated the number of total jobs created during that period at 76,273. "Therefore, 76,273 divided by 7.5 (years) is 10,169 jobs per year," Ishikawa said.

PRP, using multipliers developed by the state Department of Business, Economic Development and Tourism, estimated the rail project will employ an average of 6,864 workers a year for 10 years both in the construction industry and the broader economy. The bulk of the hiring is projected to occur in years 2013 and 2014 when the number of jobs would total 12,104 and 11,705, respectively.

PRP also produced job estimates using DBEDT multipliers for just the construction industry. Using that methodology, PRP projected the rail project would generate an average of 4,887 construction jobs a year, peaking at 8,593 positions in 2013 and 8,240 in 2014.

The Bureau of Economic Analysis and DBEDT multipliers were developed using an "input-output model," a tested economic technique that employs a mathematical formula to quantify relationships between different sectors of the economy. UHERO, meanwhile, used an economic model that correlates historical data on local building permit activity and job creation to project future job growth.

"There is a large difference between our estimate and theirs," Carl Bonham, executive director of UHERO, said of the figures in the EIS. "It’s difficult to compare the two. Neither method — the I-O and our statistical models — are perfect."

The city broke ground in February on the planned 20-mile elevated commuter rail line that will run from East Kapolei to Ala Moana. Completion is set for 2019.

Officials from Kiewit Building Group, which won two big rail contracts, said it is difficult to come up with an exact job count because much of its work is being done by subcontractors.

Kiewit began construction in April on the first phase of the elevated guideway in Waipahu. Kiewit Senior Vice President Lance Wilhelm said "several hundred" of the company’s tradesmen would be assigned to the project as well as 150 or more salaried professionals, including engineers, designers, superintendents and business managers.

"Our subcontractors will no doubt be employing many more workers themselves," Wilhelm added.

The timing of the rail project could not have been better for the construction industry, he said.

"We have been monitoring the activity of the design and development communities, and we simply do not see any project anywhere near as large or as impactful on the current construction labor market as the transit program," Wilhelm said.

"There is no ‘shovel-ready’ project, public or private, that will have the kind of immediate impact on the jobs market and the economy as a whole, as the rail project."