Supporters of moving freight train traffic to make room for the metro's biggest light-rail line were dealt another setback Tuesday when a consultant with ties to the freight industry declined to help look for a new route.

The decision could leave planners of the Southwest Corridor light-rail with costly and unpopular options for rerouting freight to St. Louis Park or for keeping it in a corridor of Minneapolis near the future LRT. Hennepin County officials had sought help from the consultant in a last-ditch effort to identify a better way to reroute the freight.

But officials said the consulting firm told them it wouldn't participate in the effort because it has a conflict of interest. Transportation Technology Center Inc., of Pueblo, Colo., is a subsidiary of the Association of American Railroads, which represents freight railroad interests.

"We have not decided next steps yet," said Laura Baenen, a spokeswoman for the Metropolitan Council, the agency overseeing the light-rail project.

Others were pressing for a new consultant.

"I'm assuming we're going to engage somebody else to do the same analysis," said Peter Wagenius, a transportation policy aide to Minneapolis Mayor R.T. Rybak.

Light-rail planners had invited the consulting firm to review rejected plans to reroute Twin Cities & Western Railroad freight to St. Louis Park or elsewhere to make room for light-rail in the Kenilworth corridor of Minneapolis.

The push for the fresh look was sparked by opposition to a Met Council option for rerouting freight traffic onto two-story berms in St. Louis Park to smooth out curves and reduce changes in elevation. While that option satisfied the railroad, St. Louis Park officials and some homeowners complained that the berms would divide the community and bring it faster, longer trains. It also would cost $200 million.

But keeping the freight in the Kenilworth corridor next to the future LRT would cost $160 million under one option that involves putting the light-rail in tunnels. This plan would address objections from some Minneapolis residents to the sight and noise that would come from having both types of rail traffic at ground level.

Officials said the firm announced it was backing out when its employees attended a workshop Tuesday with Southwest planners. The firm "stated it has a conflict of interest and cannot undertake technical evaluation of the freight rail relocation options in St. Louis Park," Baenen said.

But Baenen said the consultants also said recent work by Southwest planners designing possible reroutes was "good and comprehensive."

No one from Transportation Technology Center Inc. could be reached for comment Tuesday.

The firm's decision comes days after Rybak, in a letter to Met Council chair Susan Haigh, pressed for an expansive review of rejected reroute options to include areas west of the Twin Cities as well as reconsidering configurations through St. Louis Park.

Pat Doyle • 612-673-4504