(CBSDFW.COM) – The North Texas Tollway Authority has begun work on adding a fourth lane in each direction of the Sam Rayburn Tollway. Drivers will soon see the work being done during their commutes on the tollway.

The NTTA said the project will add a fourth lane to the entire 26-mile length of the tollway which runs from Denton Tap in Coppell to U.S. 75 in McKinney.

Officials anticipate the project to be done by 2021 as long as weather permits.

“These Sam Rayburn Tollway improvements are part of NTTA’s continuing efforts to improve mobility in North Texas,” said NTTA Assistant Executive Director of Infrastructure Elizabeth Mow. “We want to maintain our 1,000 lane-miles of roads and enhance their usefulness by proactively reviewing and addressing the capacity of our system.”

The NTTA said the construction will be done behind concrete barriers and won’t require additional right of way. Officials are asking drivers to be aware of changing conditions and construction vehicles during the project.