Project FAQs

What is the MoPac South Environmental Study?

The MoPac South Environmental Study is thoroughly analyzing the MoPac Expressway from Cesar Chavez Street to Slaughter Lane to determine the best alternative for improving mobility. The result will be documented in an Environmental Assessment that will consider "build" and "no build" options, as well as traffic management strategies. A full range of alternatives were developed and shared at a November Open House. The range of alternatives were designed to take into account the needs of drivers, transit riders, bicyclists and pedestrians as well as surrounding businesses, neighborhoods and the environment.

In February 2015, after extensive analysis of the engineering feasibility, social, economic and environmental impacts of each alternative, as well as consideration of public input, the study team recommended that the Express Lane(s) Alternative move forward for further evaluation.

In November 2015, through additional evaluation, the project team shared six different potential Express Lane(s) Alternative configuration options. These are currently being evaluated to determine which configuration option should move forward. 

What problem is the MoPac South Environmental Study addressing?

MoPac Expressway south of Cesar Chavez Street is a vital transportation artery for Austin. Constructed between 1973 and 2013 as a four to six lane divided highway, this section of MoPac attracts up to 130,000 cars and trucks per day. Over time, growth in the corridor - residential, retail and commercial - has led to increased congestion and reduced mobility.

In southern Travis and northern Hays counties, the population is projected to grow by 61 percent and employment is projected to grow by 74 percent by 2035. 

If nothing is done, it could take an additional half hour to drive between Cesar Chavez Street and Slaughter Lane in 2035.

Who is conducting this environmental study?

The Central Texas Regional Mobility Authority (Mobility Authority) and the Texas Department of Transportation (TxDOT) are developing the MoPac South Environmental Study cooperatively with Capital Metro and other local partners. 

What are the study boundaries?

The study area is an approximately eight mile segment of MoPac Expressway from Cesar Chavez Street to Slaughter Lane.

What environmental resources will be studied?

Potential impacts to the following will be considered:

  • Endangered species and wildlife
  • Barton Creek Greenbelt and Barton Springs
  • Edwards Aquifer Recharge Zone and water quality
  • Water resources, wetlands, floodplains
  • Vegetation
  • Cultural resources
  • Traffic noise
  • Air quality
  • Socio-economic issues, including community cohesion
  • Geology and soils
  • Visual and aesthetic qualities
  • Parkland
  • Bicycle and pedestrian facilities

What are direct, indirect, and cumulative impacts?

The study will assess the direct and indirect impacts of proposed transportation improvements to the environment. Potential direct and indirect impacts will also be analyzed cumulatively, together with the effect resulting from other past, present and future actions.  

  • Direct Impacts caused by a roadway improvement could include commercial and residential displacements, impacts to waters of the U.S. including wetlands, or impacts to historical properties.  Such impacts occur at the same time and in the same location the improvement is implemented.
  • Indirect Impacts caused by a roadway improvement could include growth inducing effects and other effects related to changes in the pattern of land use, population density or growth rate as a result of the project.  While not directly impacting a resource, indirect impacts could still manifest in such areas as air quality, water quality, or habitat values.  Such impacts, while reasonably foreseeable, are farther removed in distance from the improvement or occur later in time.
  • Cumulative Impacts are focused on the incremental impacts of the roadway improvement when combined with other past, present and reasonably foreseeable future actions.  Cumulative Impacts may be the result of projects or activities implemented by other entities. For example, potential cumulative impacts on water quality may stem from infrastructure improvements implemented by public agencies combined with land development activities initiated by private entities, as well as any direct and indirect impacts generated by the proposed action.

What is the timeframe of the study?

The study began in May 2013 and is anticipated to be complete by the end of 2016.

What preliminary alternatives were considered for MoPac South?

The preliminary alternatives included:

Add General Purpose Lane(s) in each direction

Add High Occupancy Vehicle (HOV) Lane(s) in each direction

Add Transit Only Lane(s) in each direction

Add Express Lane(s) in each direction

Transportation Systems Management (TSM) /  Transportation Demand Management (TDM)  [TSM: a collection of low-cost (non-capital intensive) strategies to enhance safety, reduce congestion and improve traffic flow; TDM: managing or decreasing the demand for auto-related travel by using a variety of measures to increase the operating efficiency of transportation facilities.]

No-Build, or “do nothing” alternative

What alternatives were recommended for further study?

Following analysis of each of the preliminary alternatives using the Purpose and Need for the project and other criteria, the project team determined that the alternatives to be studied going forward were High Occupancy Vehicle Lanes, Transit Only Lanes, Express Lanes and the No Build alternative.

The No Build alternative must be carried throughout the study as a baseline for comparison. Under this scenario, routine maintenance of the corridor would continue. This alternative also assumes any other improvements/strategies in the Capital Area Metropolitan Planning Organization’s Long Range Transportation Plan would move forward.

What is the study's recommended reasonable alternative?

Following analysis of each of the alternatives recommended for further study using the Goals and Objectives for the project and other criteria, the project team determined that the recommended reasonable alternative to be studied going forward is the Express Lanes alternative.

The No Build alternative must also be carried throughout the study as a baseline for comparison. Under this scenario, routine maintenance of the corridor would continue. This alternative also assumes any other improvements/strategies in the Capital Area Metropolitan Planning Organization’s Long Range Transportation Plan would move forward.

How are mobility improvements developed and selected?

At the beginning of any environmental study, the community is invited to help define a Purpose and Need for improvement. Concepts are developed that meet the Purpose and Need, and the community is invited to provide additional input on the development and evaluation of all proposed improvements. A "no build," or "do nothing" alternative, will be carried through the process and used as a baseline for comparison.

Public feedback is then combined with engineering feasibility, social, economic and environmental analyses of each alternative to identify the best options, ultimately leading to the identification of a preferred alternative. As the environmental study nears completion, a preferred alternative will be presented at a public hearing. With support from its partners, the Mobility Authority will make a final recommendation to TxDOT.

Will any bike and pedestrian improvements be considered as part of the study?

Yes, bike and pedestrian facilities will be considered as part of the study process. The study's Recommended Reasonable Alternative, Express Lanes, would include more than $6 million in bicycle and pedestrian improvements. The project would include an ADA-compliant Shared Use Path along the corridor that connects with existing and other planned pedestrian and bicycle facilities. The result would be an eight-mile, continuous facility for pedestrians and bicyclists from Slaughter Lane to Lady Bird Lake. Proposed improvements also include construction of ADA-compliant sidewalks where feasible within the TxDOT right-of-way, including along cross streets. This provision allows the project to link to the existing city of Austin sidewalk network along the east and west sides of the corridor.

Will improvements to MoPac South be tolled?

If the study's Recommended Reasonable Alternative of Express Lanes moves forward, the improvements would be tolled.

What is the Green Mobility Challenge?

In July 2011, the Mobility Authority, in partnership with TxDOT, launched the Green Mobility Challenge, a sustainable design competition that challenged Texas' most creative landscape architects, planners and engineers to propose better ways of constructing, operating and maintaining future transportation projects. Ideas submitted as part of the challenge are being evaluated for inclusion in the MoPac South Environmental Study where feasible. More information is available at www.GreenMobilityChallenge.com.

How is the Lady Bird Johnson Wildflower Center involved in the MoPac South Environmental Study?

The Wildflower Center will evaluate the current level of ecosystem function along the corridor and then make recommendations on areas in which to preserve, restore or enhance ecosystem function. They will also suggest appropriate, plant based, storm water management strategies to enhance hydrologic function.

Healthy, natural systems provide ecosystem services such as slowing, capturing and cleaning water, enhancing our water supply and mitigating flash flooding. Sustainable roadside projects seek to preserve and, in some cases, enhance, these services while allowing for the development of much needed infrastructure. More information can be found at http://www.wildflower.org/sites.

Does our drinking water come from the Edwards Aquifer?

Drinking water travels a long way before it reaches the tap. Customers of the City of Austin Water Utility (Utility) receive their drinking water from two water treatment plants that pump surface water from the Colorado River as it flows into Lake Austin. Water treatment plant IV pumps drinking water from Lake Travis. The City of Austin treats and filters the water according to federal and state standards to remove any possible harmful contaminants.

The Edwards Aquifer is an underground layer of porous limestone that stores water, stretching from Temple to Del Rio. Although it is not a source of drinking water for the city of Austin, it is the sole source of drinking water for 1.7 million people in Central Texas (TCEQ 2015), provides habitat for two endangered salamander species and discharges at Barton Springs (BSEACD 2014).

How would the project protect the Edwards Aquifer if improvements are built?

The segment of MoPac under study is within the Edwards Aquifer recharge zone, a 1,250 square mile area that allows large quantities of water to flow into the Aquifer through highly porous limestone. Because of this, the project would include the preparation of, and compliance to, a Water Pollution Abatement Plan for approval by the Texas Commission on Environmental Quality (TCEQ). Additionally, any new impervious cover over the Recharge Zone must meet the Edwards Aquifer rules for the removal of Total Suspended Solids (TSS) from storm water runoff. TSS is a water quality measurement used to describe the concentration of pollutants in water runoff.

Through the implementation of TCEQ's Edwards Aquifer rules, the project would utilize existing and new water quality structures and other Best Management Practices (BMPs) to remove at least 80% of TSS from the roadway storm water runoff prior to its release into the surrounding ecosystem. The project would consider upgrading or replacing existing water quality structures as well as the use of permeable pavement, vegetated filter strips, and construction of new water quality ponds to achieve this level of TSS removal.

If the project is environmentally cleared, a Stormwater Pollution Prevention Plan (SWPPP) will be developed to describe all of the stormwater management plans and BMPs to be included in the project. The SWPPP will include a description of the emergency procedures to be used in the event of a hazardous spill during construction, as well as other construction-phase protections, including the use of sediment curtains to contain any disturbed sediment and prevent sediment displacement.

What is Context Sensitive Solutions?

The study team is initiating a Context Sensitive Solutions (CSS) process so that any mobility improvements that may be implemented would fit into the surrounding physical setting while reflecting the unique features and characteristics of the project area. More information can be found about CSS at http://contextsensitivesolutions.org/.

How is this environmental study related to other projects in the region?

The MoPac South Environmental Study is an independent study to look at mobility improvements along MoPac Expressway from Cesar Chavez Street to Slaughter Lane. The study is not an extension of the MoPac Improvement Project, which is currently under construction (visit MoPacExpress.com for details). Nor is it part of the MoPac Intersections Environmental Study.

Why aren’t MoPac South, the MoPac Intersections and SH 45SW being considered under a single study?

The Texas Department of Transportation and the Central Texas Regional Mobility Authority are working together to conduct environmental studies on several projects, including MoPac South and MoPac Intersections. SH 45SW recently received a Record of Decision and is moving forward into final design.

Each of these projects is included as a stand-alone project in the Capital Area Metropolitan Planning Organization’s (CAMPO) 2040 Plan, and as such, is being studied separately.

In addition, each of these projects has independent utility, meaning each would benefit drivers and would be considered a reasonable expenditure, even if no additional transportation improvements in the area are made; therefore they are being studied independent of one another. If built, these projects could function as stand-alone improvements, even if other improvements in the area do not advance, or advance at a different schedule.

Is one of the options being considered to extend the Express Lanes being constructed along north MoPac?

The addition of Express Lanes from Cesar Chavez Street to Slaughter Lane is one of several preliminary alternatives that was analyzed as part of this study. The study's Recommended Reasonable Alternative would extend the Express Lanes being constructed along north MoPac. 

The MoPac South Environmental Study is a stand-alone project and mobility improvements (if implemented), would not depend on the Express Lanes being constructed along north MoPac to function.

What are Express Lanes? How do they work?

Express Lanes are special separated lanes that are designed to remain congestion free. They utilize variable toll pricing to manage the amount of traffic in the lanes. This is accomplished by increasing the toll when traffic is heavy and lowering it when traffic is light. Variable toll pricing is intended to keep traffic in the Express Lanes free flowing, giving public transit buses, Capital Metro registered carpools, vanpools, MetroAccess vehicles, emergency responders, state and federal military vehicles and drivers who choose to use the Express Lanes a faster and more reliable trip.

What is variable toll pricing?

Variable toll pricing is used to manage the number of vehicles using Express Lanes at any given time. When traffic is heavy and demand for the Express Lanes is high, toll rates increase. When demand is low, toll rates go down.

  • To keep the Express Lanes from becoming congested, individual drivers are charged a variable toll to manage the number of vehicles using the Express Lanes at any given time
  • When traffic is heavy and demand for the Express Lanes is high, toll rates increase. When demand is low, toll rates go down
  • Electronic signs display the current rates, so drivers know the price before deciding whether to enter the Express Lanes
  • Are toll-exempt for emergency responders, state and federal military vehicles, public transit buses, Capital Metro registered carpools and vanpools, and MetroAccess vehicles, providing them with a reliable, uncongested, non-stop route to their destination
  • The primary goal is to keep the Express Lanes free flowing as much as possible

Why can't we build general purpose lanes instead of Express Lanes?

Even if funding was available to construct general purpose lanes, latent traffic demand, or drivers who currently use other routes to avoid MoPac South congestion, would quickly fill these lanes, and they would become congested like the existing general purpose lanes on MoPac. The approach to solving congestion by simply adding multiple lanes of pavement is not sustainable and has not proven to be effective in managing traffic and promoting transit. Express Lanes are being implemented around Texas and other states to manage congestion rather than patching the problem just to face the same challenges in a few years.

If there is room to add two lanes in each direction, why can't one of them be a general purpose lane?

Adding one general purpose lane and one Express Lane in each direction instead of adding two Express Lanes in each direction would reduce the capacity and operational efficiency of the proposed Express Lanes, without adding appreciable improvement in speed or reduction in delay on the general purpose lanes.

If another general purpose lane was added to the corridor, it would fill up with traffic just like the existing MoPac. Even adding two general purpose lanes in each direction would not address congestion issues on the corridor during the morning and evening peak periods in 2035. Adding one general purpose lane would have even less impact on average speeds.

Will any of the project be elevated?

The majority of additional structures proposed for this project will match the elevation of the current MoPac structures. However, the project team initially developed a plan to elevate the new MoPac lanes 25 – 30 feet above the existing MoPac bridge over Lady Bird Lake to make a connection with Cesar Chavez.

The Mobility Authority heard the community's concerns about the impact of this preliminary concept. The project team is evaluating six different operational configurations, shared at an Open House in November 2015. 

The project team is working to identify which operational configuration should move forward. When the identification is made, it will be shared with the community.

NEW: How do  you plan to address noise?

A noise analysis is currently underway as part of the environmental study.  The analysis considers the current level of noise at many locations throughout the study area, calculates existing and projected future traffic noise levels, and considers noise reduction measures if the predicted future noise levels exceed acceptable noise levels for properties that surround the project. The results of that analysis will be made available at future public meetings and will be included as part of the Environmental Assessment document. 

The most common noise reduction measure is the construction of noise barriers or sound walls. If the noise analysis shows that noise levels exceed acceptable standards in a particular area, the project will provide sound walls if they are determined to be feasible, reasonable and to the adjacent property owners. Feasibility considers whether a substantial noise reduction can be achieved and whether the noise barrier will cause a reduction in safety. Reasonableness considers, among other factors, cost effectiveness, expected noise levels, and land use. Acceptability considers the opinions of the residents that live adjacent to the proposed wall.

The adjacent property owners being affected must support the implementation of the sound wall for it to be constructed. Whether the property owners support the implementation of the sound wall(s) is determined by the result of Sound Wall Workshops that would be conducted after the environmental study is completed, if a build alternative is approved for construction. Ultimately, a vote of the adjacent property owners would be taken regarding each wall to determine which ones will be constructed.

Why should the project have two Express Lanes in each direction, rather than one?

Many agencies avoid, if possible, providing only one lane in each direction, for several reasons.

Reliability: Constructing only one lane in each direction makes it more likely that drivers who use the project will experience disruptions in reliability. Minor incidents, even a flat tire, could easily disrupt the flow of traffic and speed in the Express Lane. Additionally, drivers who choose to travel at slow speeds in the Express Lane would impact the travel time reliability of all trailing vehicles.

Incident management: Constructing two lanes in each direction provides the additional capacity needed to enable a faster and easier response to incidents in the corridor.

Access: With two lanes in each direction, one is available to support entering and exiting traffic and one lane can support through traffic. A project with only one lane in each direction is much more likely to experience disruptions in the traffic flow.

The MoPac South Environmental Study team will continue to evaluate, review and present information on both the two total lane option and the four total lane option.

While providing two Express Lanes in each direction is optimal, the MoPac North project will only have one Express Lane in each direction due to restricted right-of-way from RM 2222 to Cesar Chavez.

How will SH 45SW affect travel times on MoPac?

The shift in local traffic to MoPac may cause travel times on MoPac to increase slightly between SH 45 and William Cannon Drive due to northbound drivers opting to use SH 45SW to MoPac instead of Brodie Lane and Manchaca Road. North of William Cannon Drive, no increase in volumes or travel times is anticipated. If the shift in local traffic patterns through the intersections in this area of MoPac create backups at signals, the city may elect to  make adjustments to signal timing. Intersection improvements at Slaughter Lane and La Crosse Avenue, currently scheduled for completion prior to completion of SH 45SW or MoPac South, could also improve travel times.

What is being proposed at Lady Bird Lake (connection to downtown)?

Providing direct access from the Express Lanes to downtown is important to ensure that the project facilitates reliable emergency response and provides a dependable and consistent route for transit. Additionally, providing direct access from the Express Lanes to downtown increases safety for all drivers by eliminating the need for Express Lane traffic to merge into the general purpose lanes to access downtown. Although the preliminary concept initially proposed includes an elevated direct connection from the Express Lanes to and from downtown via Cesar Chavez, the Mobility Authority has heard the community's concerns about the impact of an elevated connection.

The project team is evaluating six different operational configurations, shared at an Open House in November 2015. 

The project team is working to identify which operational configuration should move forward. When the identification is made, it will be shared with the community.

Why are we conducting an Environmental Assessment instead of an Environmental Impact Statement?

An environmental assessment is recommended if environmental impacts are not known or cannot be clearly established. An environmental impact statement is prepared if significant environmental impacts are predicted. This decision is made as part of a rigorous risk assessment performed jointly by the TxDOT Environmental Affairs division and the sponsoring agency.

How much is the project anticipated to cost?

The MoPac South project is anticipated to cost between $350 and $400 million. We anticipate adjustments to this figure as additional design activities are conducted.

Would the Express Lanes Alternative require any new right-of-way?

Some of the six configurations currently under consideration for the Express Lane(s) Alternative do require varying amounts of new right-of-way. For more information, check out the "Estimated Additional Right-of-Way" sections of each Configuration Fact Sheet.

What will the MoPac South toll rate be?

A traffic and revenue study will be completed to determine the potential range of variably priced Express Lane tolls for the proposed MoPac South project. Tolls could range from $0.25 to $4.00 per trip, but could be higher if demand is greater than anticipated.

What impact will the Express Lanes have on Austin High School and the traffic on Cesar Chavez Street?

The Mobility Authority arranged for an independent traffic study to evaluate the impact that the Express Lanes would have not only on Cesar Chavez Street and the traffic near Austin High, but on the rest of the surrounding downtown street grid. 

The study showed that the addition of Express Lanes on south MoPac would not adversely affect congestion on Austin's downtown street grid as a whole. This is true for any of the operational configurations evaluated. All configurations either improved or had negligible impacts to travel times within the downtown network. 

Will the Express Lanes attract truck traffic?

Large trucks and vehicles with trailers will not be allowed in the Express Lanes.

How will the Express Lanes promote transit ridership?

Adding Express Lanes to MoPac South would be a significant improvement for transit, specifically bus transportation. The Mobility Authority's policy allows public transit buses such as Capital Metro to drive on the Express Lanes without paying a toll. Because the variable toll in the Express Lanes would be priced to maintain uncongested traffic flow, transit riders would be ensured a reliable trip, even during peak periods, which will make riding transit a true alternative to driving alone. The team is also working to determine appropriate locations for Park and Rides.

What is the MoPac Intersections Environmental Study?

At the same time the MoPac South Environmental Study is underway, a separate study is being conducted to assess possible improvements at the intersections of MoPac Expressway with Slaughter Lane and La Crosse Avenue.

In light of the public input received last fall and our continuing engineering analysis, the Central Texas Regional Mobility Authority and the Texas Department of Transportation are designing underpasses at Slaughter Lane and La Crosse Avenue. A “do nothing” or No-Build option is also still under consideration.

For more information about this study, visit the Intersections Study page on www.MoPacSouth.com for details.

Who can ride toll-free on toll lanes operated by the Mobility Authority?

On toll lanes or toll roads operated by the Mobility Authority, which would include MoPac South Express Lanes if they are constructed, the following can drive toll-free:

  • Emergency responders
  • State and federal military vehicles
  • Public transit buses
  • Capital Metro registered carpools and vanpools
  • MetroAccess vehicles

Is it too late to provide feedback?

The project team continues to take comments from the public through the project website. At the next public event, stakeholders will be able to review the Express Lane configuration that will move forward, speak with the project team and submit another round of official comments. We would also be happy to meet with any neighborhood or community group to share information about the project and receive input. If you would like to schedule a meeting, contact us.

What happens to the feedback I submit?

First, each comment is sorted and categorized to ensure that the project team counts each perspective and vets each idea. Design ideas and suggestions are shared with the design team, who evaluates whether the suggested design changes or additions would be beneficial and feasible. After comments are sorted, categorized and routed to the correct team members, responses are developed for each comment. All comments submitted during an Open House comment period (which, by law, extends 30 days prior to an Open House and extends 10 days after) and their responses will be published as part of the Open House Comment and Response Summary, released to the public in the months following the Open House. All comments submitted outside of the official comment period of an Open House will not be recorded as part of the Open House Summary Report but will become part of the official Project File for the Environmental Study and are also reviewed and considered by the study team.

How can I stay informed about the project and get involved in the process?

Public participation is critical to the study. Corridor residents, businesses, roadway users, local agencies, the general public and other interested parties can obtain information about the project in many ways, such as:

Team members are also available to meet with neighborhood associations, community groups and others to discuss issues of concern, various improvement options and the results of engineering and environmental analyses. Feedback and input are encouraged and can be provided to the study team in person at public meetings, online at www.MoPacSouth.com or submitted in writing to: Central Texas Regional Mobility Authority, C/O MoPac South Environmental Study, 3300 North IH-35, Suite 300, Austin, Texas 78705.

Contact Us

3300 N. IH-35 Suite 300
Austin, TX 78705

(512) 996-9778 Email Us
Contact Us

3300 N. IH-35 Suite 300
Austin, TX 78705

Call (512) 996-9778
Email Us