The contractor building the $2.7 billion Southwest light rail line claims the state watchdog agency probing the troubled project has ignored critical issues with its design that have led to millions in cost overruns and years of delay.

The head of Lunda/C.S. McCrossan Joint Venture (LMJV), which is building Southwest, further charged that the Office of the Legislative Auditor (OLA) lacks the necessary expertise to criticize or offer a legal opinion on the way the 14.5-mile line has been constructed.

Had the Metropolitan Council, which is overseeing the Southwest project, followed recommendations recently shared by the Legislative Auditor, the opening of the line would have been "pushed out further by years," cost "significantly more" and perhaps faced "very bad litigation," according to a July 10 letter written to Legislative Auditor Judy Randall by Dennis Behnke,CEO of Wisconsin-based Lunda Construction Company.

As it stands now, the Southwest line connecting downtown Minneapolis with Eden Prairie — an extension of the Green Line — isn't expected to begin service until 2027, although about 75% has already been built.

Randall declined to comment on the letter Tuesday, but says she stands by the OLA's work which demonstrates the agency's "expertise in government oversight, transparency, and accountability, and reflects the commitment to accuracy and good government."

Southwest's woes have brought at the Capitol, and investigations by the Legislative Auditor have attempted to pinpoint what went awry with the project.

Last month, OLA released a review claiming the Met Council failed to effectively enforce the main contract with LMJV for overseeing construction of the line. LMJV was awarded a $799 million bid in 2018 to build Southwest.

But in a statement to the Star Tribune, Behnke said the construction firm "was given a poorly prepared set of plans to construct the largest public project in Minnesota history that was subject to an unprecedented level of continual change."

LMJV doesn't attribute design issues to any particular part of the project, which is enormously complicated with 16 stations, 29 bridges and two light rail tunnels. Instead, the 11-page letter to Randall says that the overall blueprint for the project was "of poor quality," incomplete, and "contained major elements that were not fully developed or thought out."

Behnke noted that LMJV was not responsible for any scheduling delays or additional costs.

A group of consultants led by Architecture, Engineering, Construction, Operations, and Management (AECOM), a publicly traded Texas-based infrastructure consulting firm, is responsible for the Southwest's overall design and engineering work. AECOM could not be reached for comment Tuesday.

The Met Council has attributed most of Southwest's issues to squeezing a tunnel in Minneapolis' narrow Kenilworth corridor, the addition of a station in Eden Prairie as well as a $93 million crash wall separating light rail and freight trains along the route's northern stretch.

As of last month, the project reported some 1,017 change orders, which are prompted when there's a deviation from the original design, according to the Met Council. While that's not unusual for a project of Southwest's size, the recent Legislative Auditor's report recommended that the Met Council tighten its practices for managing big construction projects, particularly those regarding change orders.

Last year, the council reached an agreement with LMJV to resolve outstanding change orders and set a timeline to complete the job — "without litigation," Behnke said. The two also collaborated to minimize the impact of the Kenilworth tunnel on the Cedar Isles condominium complex, he added.

This week's letter appears to reinforce LMJV's growing frustration with the Legislative Auditor's review, claiming it "fails to appreciate the difficulty of building a $800 million project in less than four years while the plans are continually changing."

Likewise, Met Council Chair Charlie Zelle responded last month that the report's recommendations are not aligned with federal "guidance or construction law, are not appropriate for a project of this size and complexity, and in some instances could have contributed to additional delay." The council declined to comment on LMJV's letter Tuesday.

At a hearing of the Legislative Audit Commission last month, Randall defended her agency's work.

"Are we experts in transit construction? No. Are we engineers? No. We don't claim to be," Randall said. "But what we are experts on is protecting the taxpayers' dollars."

A final report on the Southwest project's financial practices is expected later this year.