THORNTON, Colo. (CBS4) – The new north Interstate 25 express lane that runs between I-270 to 120th Avenue in Thornton will be open to traffic on Monday.

Drivers will be able to use the lane for free on opening day.

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The southbound lane will be free and open for testing on March 21.

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The Colorado Department of Transportation wants to give drivers a chance to understand how the lanes work before they start charging.

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LINK: Traffic Section