DENVER — RTD said had so many riders on the A Line that it needs to add more train cars to accommodate ridership. Laurie Huff, a spokesperson for RTD, said starting early next year, RTD will be adding those additional cars to the commuter train to the plane. They're still figuring out how many.

According to Huff, officials had to make the decision to add more cars a year earlier than they had even planned to consider it.

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"That's important because its a direct reflection of higher ridership," she said. "To date, we've had more than 16 million people take rides on the A Line since it opened in April 2016, and we serve thousands of people on that line every day."

Huff said RTD didn't plan on carrying 16 million riders until 2020. The future of the A Line is still in doubt though because of ongoing issues with rail crossing gates. Federal regulators have threatened to shut down the line if RTD doesn't submit a plan for fixing the issues and the G Line to Arvada and Wheat Ridge still can't open until all this gets resolved.

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