On Monday, the Texas Department of Transportation unveiled an updated $8.1 billion plan to build  two toll lanes in each direction of I-35 from RM 1431 in Round Rock to SH 45 SE near Buda. The cost for the updated plan—part of the agency’s overall My35 plan to improve traffic flow on one of the state’s most congested highways—is nearly double initial costs of $4.3 billion for adding one managed lane in each direction and making other improvements in Hays, Travis and Williamson counties. The updated plan also calls for reconstructing I-35 and lowering the highway in downtown Austin. “Having a new and improved I-35 is something we have been waiting on for generations,” state Rep. Celia Israel, D-Austin, said Monday. “I am excited to see TxDOT take community input and help us fulfill that vision. This is a game changer when it comes to safety as well as improving this critical Texas asset.” HERE ARE 5 THINGS TO KNOW ABOUT THE UPDATED I-35 PLAN: 1. The toll lanes, also known as managed lanes, would be called the Capital Express. These lanes would run along 33 miles of I-35 from RM 1431 to SH 45 SE. Managed toll lanes would be separated from the main lanes by a barrier, similar to the ones now open on MoPac. Tolls increase when traffic increases to manage the flow in the toll lanes. "Adding two managed lanes in both directions will relieve congestion and give commuters more freedom to choose what works best for them," said Anne Wynne, the 2017 Greater Austin Chamber of Commerce Transportation Committee chairwoman. "Improved traffic flow from the four managed lanes will also improve freight delivery times and help our region attract more job creators to help further diversify the Austin region's economy. This big step forward shows our current and future residents and employers that we are planning for a future transportation system and infrastructure that works for the region.” 2. Construction could be phased. The agency likely would prioritize the section downtown Austin first because of need. It could build interim traffic relief solution from SH 45 N to SH 45 SE. Construction could begin as early as 2021. “Addressing congestion along I-35 is a top priority for the Austin District,” TxDOT Austin District Engineer Terry McCoy said in a news release. “I-35 is a critical path through Austin and serves as our state’s main thoroughfare for goods and services. This project will ensure reliability when drivers need it most.” 3. TxDOT is still weighing ideas on how the lanes would be added. Agency officials report adding four total managed lanes would “require extensive reconstruction of I-35.” Options for fitting the managed lanes in include lowering I-35 in downtown Austin, removing the upper decks from Martin Luther King Jr. Boulevard to Airport Boulevard or building the managed lanes under the main lanes in areas with little right of way. In 2013, city officials and transportation advocates began discussing a cut-and-cap proposal to lower the upper deck of I-35. 4. TxDOT will be able to use existing work from the ongoing environmental study. The agency has already been soliciting feedback from residents through three separate environmental studies. TxDOT will have to complete one environmental study from RM 1431 to SH 45 SE but plans on incorporating existing public input. Additional open house events will occur next spring, and an environmental decision of the project’s impact on the environment is expected to be delivered in 2019. 5. The proposal also includes other improvements besides toll lanes. Operational improvements would also be included, such as extending entrance and exit ramps, adding lanes to bypass an intersection and adding pedestrian and bicycle improvements. 6. Some work to improve I-35 is already underway and other projects have been funded. Projects in Hays County, North Austin, South Austin and Round Rock are already underway to improve traffic flow, all funded through Proposition 1 that diverted more money to the State Highway Fund. In March, the Texas Transportation Commission approved $2.6 billion in funding for projects in the state’s largest metropolitan areas as funded through Proposition 7, which also allocates more funding to the State Highway Fund. Funding was approved as part of the agency’s Texas Clear Lanes initiative. About $133.3 million would go toward building flyovers between I-35 and US 183 and $162. 3 million would go toward improvements on I-35 from Holly to Oltorf streets. “The Capital Express project along I-35 in Austin aligns perfectly with our statewide Texas Clear Lanes strategy to address some of the most congested roadways in Texas,” commission chairman J. Bruce Bugg, Jr. said.