The contractor installing the driverless operating system for the city’s 20-mile Honolulu rail project has filed a “mega-substantial” claim with the Honolulu Authority for Rapid Transportation seeking compensation for construction delays on the project.

HART Executive Director Andrew Robbins declined to say how much money contractor Ansaldo Honolulu Joint Venture is seeking because a settlement in the dispute is still being negotiated.

The claim was filed about 18 months ago, and seeks a “mega-substantial” amount, according to HART board member Ember Shinn.

Ansaldo signed a $1.4 billion contract with the city in 2011 that included $574 million for the design and construction of the train control systems, and also for delivery of 80 train vehicles. Ansaldo is also to be paid $830 million for operating and maintaining the rail system over 14 years.

That was the largest single contract in city history at the time, and Robbins said Ansaldo’s contract was based on a city construction schedule that called for the entire rail line to be completed by 2019. However, lawsuits and other problems have caused years of delays, and the current completion date for rail 2025.

Ansaldo is claiming damages because of the delays, but the claim is mostly based on the $574 million design and construction portion of the contract, Robbins said. HART is arguing Ansaldo could have or should have taken mitigating steps to reduce the costs associated with the delays, but Robbins declined to be more specific about those negotiations.