AUSTIN (KXAN) — The Texas Public Interest Research Group, Environment Texas and ReThink 35 will file a lawsuit against the Texas Department of Transportation Monday.

The lawsuit alleges TxDOT “violated the law” by splitting up the Interstate 35 Capital Express Projects into three sections versus one larger project.

“The purpose of the lawsuit is simply to force TxDOT to go back and bring these three projects that are currently three separate projects back to the public as one complete project and have the public review this as one overall project,” explained Adam Greenfield, the executive director of the grassroots organization ReThink 35.

TxDOT did not comment on the pending lawsuit matter.

The I-35 Capital Express Projects consist of the north, central and south sections that, when combined, stretch along I-35 for about 30 miles from State Highway 45 North in Round Rock down south to State Highway 45 Southeast near Buda.

TxDOT has said in the past the projects will enhance, make improvements and add capacity to the busy highway.

Those with the two nonprofits and ReThink 35 claim TxDOT is avoiding a “more rigorous environmental review and public engagement of a single larger project” by dividing up the sections.

“Do a thorough environmental review that looks at aspects like air quality, noise, carbon emissions, also other aspects like serious and fatal crashes and also give us real meaningful alternatives,” Greenfield said. “Not just another highway expansion”

The City of Austin has said online “the reconstruction of I-35 is one of the most important mobility projects for the Central Texas region, and critically important for all partners to get right for the future of the area.”

Both the northern and southern sections of the I-35 Capital Express Projects are expected to begin construction this year.

The north project will add one high-occupancy vehicle or HOV lane in each direction. The south project will add two HOV lanes in each direction, intersection bypass lanes and make improvements to pedestrian and bicycle paths.