The already delayed completion of Denver’s newest commuter rail line will likely slip further into 2020, the result of an ongoing dispute between the city’s Regional Transportation District (RTD) and Regional Rail Partners, a design-build joint venture led by Balfour Beatty and Graham.

Construction of the $343-million, 18.5-mile electrified N Line began in 2015, with the first 13-mile segment originally scheduled to open three years later.

Disagreements of responsibility for repeated delays led to a legal battle that ultimately led to arbitration in 2018.

According to an RTD statement, the agency and contractor “continue to work on civil and systems elements” to complete the first section, adding that “specific milestones still must be met” before finalizing an opening date.