That move could be a signal that a settlement between the parties isn't likely.
Issues with the A Line's crossing gates required train operators to blare their horns at every crossing, annoying nearby residents.
The truckers say they need an unbiased party to study the issue and help find a solution.
Less than 50 gallons of fuel spilled and clean up was complete late Friday morning.
The break from contractor Denver Transit Partners has divided some of RTD's board of directors.
Hazmat trucks cross RTD's tracks at Chambers Road between 600 to 1,000 times a day. They say an accident there could be catastrophic.
The to-do list includes more data collection, software improvements and studies of how the train itself operate.
From why the feds are issuing threats now to the difference between commuter rail and light rail.
At issue are crossing gates that, in some instances, come down too early and stay down too long.
In its filing, Denver Transit Partners also urged the court to reject RTD’s counterclaims.