A dispute between Union Pacific and contractors threatens to slow construction of California’s high speed rail line.

Contractor Tutor Perini and other companies building a section of the project in the Central Valley have complained that UP is causing delays and cost increases that could lead to a delay claim against the state.

The dispute involves UP’s right-of-way alongside the 31-mile segment of high speed line passing through Fresno and Madera, according to a published report in the Los Angeles Times.

Union Pacific warned the state in a 2010 letter against construction along its route that would disrupt or limit access to customers. A contract now worth $69 million was awarded in 2015 to cover UP’s costs.

In a June letter to the California High Speed Rail Authority (CHSRA) obtained by The Times, Tutor Perini and its team of contractors cited construction delays “solely due to [UP’s] unreasonable rigid demands and unwillingness to cooperate.”

Union Pacific refused to approve 75 Tutor Perini design documents, the letter states, “with little explanation,” and that efforts by the CHSRA to foster cooperation with the railroad “have not been fruitful.”

The letter further points to 20 instances where the railroad has interfered with construction of shoe-flies, utility relocations and staging areas, adding UP has refused to meet to resolve issues. The letter also alleges the railroad has repeatedly violated a broad engineering and construction management agreement, and that Authority’s failure to enforce the terms of that agreement “continues to severely impact the project cost and schedule.”

Along with the Central Valley, the CHSRA will need Union Pacific’s cooperation to build 30 miles of track on UP-owned right-of-way between Gilroy and San Jose. The railroad has asserted there is no agreement there.

There isn’t “any specific tension that is occurring” with UP, according to Thomas Fellenz, CHSRA chief counsel, who met with Tutor Perini but has yet to speak with Union Pacific.

The two organizations “maintain open lines of communication,” Justin Jacobs, a Union Pacific spokesman, told the newspaper.

“Any proposed design or project details that do not meet the standards and requirements outlined in the original agreement may require re-submission,” he said. “Union Pacific and CHSRA will continue our good working relationship and proactive coordination on this project.”

Tutor Perini did not respond to a request for comment.

Delay claims are nothing new to the project. The state settled one with the Tutor-led team for $50 million, and in 2017 the team said it has another worth more than $200 million.

The Madera-Fresno segment is years behind schedule, and at $1.5 billion is projected to be 50% over budget, according to the Authority’s July operations report. The entire Bay Area to Southern California project is 11 years behind its original completion date, with estimated costs rising from $33 billion to $77 billion.