Project Overview

What We Are Building

The Central Texas Regional Mobility Authority is extending the 183A Toll Road 6.6-miles northward from Hero Way to north of SH 29 in Liberty Hill as Phase III of the 183A system. The project will include two tolled lanes in each direction located primarily within the existing median of the US 183 corridor, with an adjacent shared use path from Hero Way to Seward Junction Loop.

Extending the existing 183A Toll will:

  • Save commuters time
  • Provide a reliable transportation option
  • Eliminate the need to use signalized intersections
  • Minimize community impacts by working within existing right-of-way.


Watch the 183A Phase III groundbreaking celebration below and learn more about how this project will have major regional significance.



The 183A Phase III extension will build on the success of the existing 11-mile 183A Toll Road, which spans from RM 620 through Cedar Park, and was constructed by the Central Texas Regional Mobility Authority as the agency’s inaugural project. The project, which consists of tolled mainlanes with non-tolled frontage roads at the north end, has significantly improved travel times and reduced traffic on adjacent roadways, including US 183. Continued growth along the 183 corridor is driving the need for additional congestion relief.

183A Phase I. A tolled roadway between RM 620 and RM 1431, with non-tolled frontage roads from RM 1431 northward to the San Gabriel River. It opened in March 2007.

183A Phase II. A 5-mile extension northward from RM 1431 to Hero Way. The extension opened in April 2012 and resulted in a significant shift of traffic from the non-tolled frontage roads to the new tolled mainlanes.

Intersection Improvements. Non-tolled operational improvements and enhancements to the US 183/183A (North) intersection were delivered in 2015 to make the intersection safer and easier to navigate and to enable better access to developments along 183A.

Bicycle & Pedestrian Facilities. The 183A Toll shared use path includes a 10-foot-wide, 7-mile long dedicated bicycle and pedestrian path that borders the 183A facility from South Brushy Creek to Hero Way. It also includes a trailhead and pedestrian bridge that crosses Brushy Creek, as well as a connection to Williamson County’s Brushy Creek Regional Trail. Phase III of the 183A system will extend the shared use path north from Hero Way to Seward Junction Loop.

For more information on the existing 183A Toll Road, visit the Mobility Authority’s website



The Central Texas Regional Mobility Authority is extending the 183A Toll Road 6.6-miles northward from Hero Way to north of SH 29 in Liberty Hill as Phase III of the 183A system. The project will include two tolled lanes in each direction located primarily within the existing median of the US 183 corridor, with an adjacent shared use path from Hero Way to the proposed Seward Junction Loop project.

Williamson County, most notably in Cedar Park, Leander, and Liberty Hill, is experiencing a population boom. Between 2016 and 2040, Cedar Park’s population is projected to grow by 31 percent, Liberty Hill by approximately 44 percent, and Leander by 271 percent. The corridor is expected to continue to attract residential and commercial development, further intensifying congestion and delays.

With this unprecedented growth, traffic volumes along US 183 are expected to increase by 183 percent by 2042, driving the need for proactive congestion relief. Increased congestion along the existing US 183 corridor negatively impacts the safety, with crashes more likely to occur at a greater frequency and severity level at cross street intersection locations. In addition, projections show that increased congestion would result in unreliable travel times negatively impacting the quality of life regionally.

The 183A Phase III project will:

  • Provide a reliable, predictable and time-saving option for drivers and emergency vehicles
  • Accommodate community growth and development along and to the north of the corridor
  • Provide an alternative route without signalized intersections 
  • Minimize community impacts by working mostly within existing right-of-way

Existing bicycle and pedestrian accommodations along 183A and US 183 within the project limits are currently limited to crosswalks and ramps at Hero Way, Bryson Ridge Trail, and SH 29, and paved outside shoulders along the general-purpose lanes. 

The 183A Phase III project will include a 10-foot-wide, shared-use path for bicycle and pedestrian use from Hero Way to Seward Junction Loop. A connecting shared use path will provide trail access to the City of Leander’s planned South San Gabriel River Park. 


The Mobility Authority has issued bonds and has been granted a TIFIA loan to finance the project.

Construction began in spring 2021 and is anticipated to be open to traffic in 2025.

Project construction will occur primarily within the existing 183A and US 183 ROW and easements and the proposed 19.3 acres of additional ROW north of SH 29.

Temporary lane closures will be minimal and primarily associated with the construction of entrance/exit ramps and grade separated intersections. Consequently, economic impacts to local businesses associated with roadway access during construction are not anticipated.

Learn more about what to expect during construction by viewing our 183A Phase III Construction Guides.

The majority of construction will take place during daytime hours, however, to minimize impacts to traffic and to ensure the safety of the traveling public, construction may occur 24 hours a day.

Construction activity will occur on US 183/183A Toll from south of Hero Way to north of SH 29 in Liberty Hill.

Overnight: Overnight lane closures may occur between 8 p.m. and 5 a.m.  

The contractor will face financial penalties if a closure occurs or lingers outside of approved time frames. In order to minimize noise from construction activities, the project team will follow a set of guidelines designed to preserve quality of life for adjacent neighborhoods. 

Most of the project will be constructed within the existing right-of-way (ROW) of 183A and US 183. We anticipate that approximately 19.3 acres of additional ROW may need to be acquired near the northern end of the project limits to construct the transition of US 183 for approximately 1.1 miles north of SH 29.

The new 183A lanes will be constructed within the existing 183A and US 183 alignment and no new-location roadways are proposed as part of the project. No displacements or relocations are anticipated and physical access to residences and community resources will remain. Changes to neighborhood cohesion, existing access to specific services, or recreation patterns at public facilities are not expected to occur as a result of the project.

The Environmental Assessment evaluated noise impacts of the proposed project to determine if noise barriers were required. The noise analysis determined that traffic noise impacts would occur at 24 homes, the planned South San Gabriel River Park, and the New Life Church playground. The projected increase in noise levels is due to the increase in travel lanes and traffic volumes. Noise levels already approach or exceed noise abatement criteria at seven locations under existing conditions. Without the proposed project, traffic noise would increase over existing conditions because of increased traffic volumes.

The results of the noise analysis indicated that one combination of two noise barriers would be feasible and reasonable as a noise abatement measure adjacent to the future South San Gabriel River Park planned by the City of Leander. Other noise walls, where feasible, would not be reasonable for the impacted receivers since they would exceed TxDOT’s cost-effectiveness criteria. No other noise barriers qualified for incorporation into the proposed project. To view the noise analysis, click here

On toll roads operated by the Mobility Authority, tolls are waived in accordance with state law and Mobility Authority policies for:

  • Emergency vehicles
  • State and federal military vehicles
  • Public transit buses
  • Capital Metro registered vanpools
  • MetroAccess vehicles
  • Qualified veterans accepted into the Qualified Veteran Discount Program

For more information, questions or concerns you may call our Project Hotline at (512) 340-1111. You can also sign-up for the e-newsletter or schedule a presentation with the project team for your organization or group.