Updated Sept. 23 at 10:15 a.m. to clarify the limits of the proposed lowered and raised design options for improving I-35 through downtown Austin The Texas Department of Transportation is taking feedback from the public on its 7-mile plan to fix the traffic congestion problems plaguing I-35 in Austin. TxDOT held an open house yesterday at Memorial United Methodist Church, 6100 Berkman Drive, Austin. Attendees learned about the Central 7-mile Comprehensive Project, also known as the Central7 project, and provided suggestions on what they would like to see. Among the improvements planned as part of the approximately $550 million-to-$850 million project spanning I-35 from Riverside Drive to US 183 are adding express lanes, one in each direction; lower or raising the mainlanes of I-35 through downtown Austin; and bicycle and pedestrian enhancements. TxDOT spokesperson Kelli Reyna said the project is in the preliminary stages, with the environmental study having kicked off this summer. "We’re looking at potentially 7 miles of improvements," Reyna said. "Anytime you are looking at a long range, in mileage, of improvements it’s difficult process." Here's what you need to know about the project:

1. TxDOT has not secured funding for it.

The agency is also deciding between two design options for downtown Austin: One would raise the mainlanes of I-35 at Cesar Chavez Street, which currently go underneath Cesar Chavez. That would cost between approximately $550 million and $650 million. The other would lower the mainlanes underneath the east-west cross streets from Cesar Chavez to Eighth Street, costing anywhere from $750 million to $850 million, according to TxDOT.

2. The project would be completed in 2025, according to TxDOT's current timeline.

If the agency receives clearance after an environmental study process expected to take three-five years, the construction bidding process could begin as early as fall 2020. That would mean a likely construction start date in early 2021 and a four-year construction process.

3. You can view videos now simulating the improvements.

Go to TxDOT's Youtube channel to view all of the proposed concepts for improving the 7-mile stretch. Here is what lowering the mainlanes of I-35 through downtown Austin would look like:

4. Transit and emergency vehicles would use the express lane for free.

Others would have to pay to take the tolled lane.

5. If you did not attend the open house in person, one is available online.

Individuals can provide their input on the project at www.mobility35openhouse.com through Oct. 4 for this round of the public input process. Reyna said there would be more opportunities to comment as the environmental study continues.