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Environmental Study

In compliance with the National Environmental Policy Act of 1969 (NEPA), TxDOT and the Mobility Authority completed an Environmental Assessment for the MoPac Corridor from Cesar Chavez Street to Parmer Lane in August 2012. The study began in July 2010 with the consideration of a full range of alternatives for improving mobility in the corridor, including adding multiple lanes or a high occupancy vehicle (HOV) lane, as well as making no improvements at all.

The environmental study found that Express Lanes with variable pricing were the preferred alternative for addressing long term mobility issues in the corridor. The study also identified where sound walls were needed to reduce roadway noise and where bicycle and pedestrian facilities needed to be improved. The study also identified aesthetic improvements for the corridor.

In August 2012, the Federal Highway Administration (FHWA) issued a finding of no significant impact (FONSI), approving this preferred alternative for implementation and construction.

Public involvement is a critical element of the environmental study process. Between 2006 and 2012, the MoPac Improvement Project Team conducted more than 30 open houses, public meetings, and neighborhood presentations. The public involvement process involved discussing various alternatives with the public and gathering feedback. Public feedback was then combined with technical analyses to identify the best option for improving MoPac. The recommended alternative was then subjected to additional public review and scrutiny, ultimately leading to the selection of Express Lanes as the preferred alternative. A final public hearing on the environmental study and the proposed Express Lanes was held on May 23, 2012 at O. Henry Middle School.

For more on the public outreach activities that took place during the environmental study phase, please see Chapter 5 of the Final Environmental Assessment and our Past Events page. 


Some sections of the document are rather large, so download times may vary.


During the design phase of the project, four design modifications were identified for consideration: 

  1. The Express Lane entry and exit ramps into and out of downtown Austin would be changed from traversing over the main lanes of MoPac to going under the main lanes of MoPac.
  2. The configuration of the southbound exit to Cesar Chavez Street and 5th Street would be modified to allow Express Lane traffic to exit to either Cesar Chavez Street or to 5th Street. The change would remove a merge condition and improve operations.
  3. An existing 42-inch water line between 35th Street and 45th Street would be abandoned in place and a new line constructed outside the MoPac right-of-way.
  4. The northbound exit ramp and access road to Steck Avenue would be slightly realigned, with no change in access.

These modifications required FHWA approval under an environmental reevaluation process before implementation. After a review of the environmental documentation and in consideration of public comment from an Open House held on September 5, 2013, FHWA agreed in early 2014 that the FONSI designation remains valid. These four design modifications will now be built as part of the overall MoPac Improvement Project.

The federally approved FONSI Reevaluation document can be downloaded and reviewed as follows:

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