Express Lanes Alternative

The Environmental Study currently underway identified the Express Lanes Alternative as the Recommended Build Alternative. Express Lanes are the recommended alternative for several reasons, including that they offer reliable travel times for single occupancy vehicles, transit buses and emergency vehicles. They also provide the shortest peak period travel time for all vehicles, including those using the general purpose lanes.


  • Express Lanes are additional lanes that would be separated from the existing non-tolled lanes.
  • Express Lanes provide public transit buses, registered vanpools and emergency vehicles with a reliable, uncongested, non-stop, toll-free route.
  • Because public transit buses, registered vanpools and emergency vehicles would not use up all the space in the Express Lanes, individual drivers would be permitted to use the lanes.
  • To keep the Express Lanes from becoming congested, individual drivers are charged a variable toll that increases when traffic is heavy and goes down when traffic is light. The primary goal is not to generate revenue, but to keep the Express Lanes free flowing as much as possible.
  • Express Lanes would encourage people to carpool because they have the option to split the cost of the trip among vehicle occupants.
  • The Express Lanes would not be intended for everyday use. There would not be enough capacity to accommodate everyone who might want to use them.
  • Individual drivers would have to decide whether any particular trip is worth the toll being charged at the time they wish to use the Express Lanes.


There are several approaches to congestion relief when a roadway faces more demand than it has the capacity to meet. One of these approaches is to build more lanes. 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 because of a factor called latent demand. Latent demand is the term used to describe drivers that would use a particular highway but, due to congestion, choose to take other routes or travel at a different time. Although adding lanes may initially decrease congestion, drivers who would normally use other routes, travel during different times, or use other modes of transportation change their patterns to fill the newly added capacity. Express Lanes, using variable toll pricing, 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.


  • To ensure the Express Lanes remain free flowing, variable tolls are used to manage the number of vehicles entering the 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.
  • Changeable electronic signs display the current rates in real time, so drivers know the price before deciding whether to enter the lanes.
  • Once you are in the lanes, the price you saw on the signs is the price you are guaranteed to pay. Drivers entering after you or at different locations may pay a different rate.
  • Tolls paid by users will be the source of money to repay the funds used to finance the Express Lanes.
  • Variable toll pricing would only apply to the two new proposed Express Lanes in each direction along MoPac South. Public transit buses, emergency responders and Capital Metro registered carpools and vanpools would be ensured a reliable trip, even during peak periods, without paying a toll.

Historical Traffic and Revenue Data

Below, you will find the sketch level (very preliminary) Traffic and Revenue information that has been a topic of discussion in 2015 with some stakeholders. Traffic and revenue modeling changes with each and every change made in conjunction with a project of this nature, sometimes quite dramatically.  The documents linked below include work done in 2014 and more recently in June 2015. Both are very preliminary in nature and not usable for market financing and distribution for funding.

The Mobility Authority chose to extend the period for consideration of the ultimate “preferred alternative” so as to study several concepts and suggestions from and for community input.  These concepts were presented at the November 10, 2015 Open House for public review and further input.

Any change to the configuration of the design can affect the operations and the capacity of the ultimate project, primarily by impacting the operations of the roadway. We expect these changes to have some impacts, and will provide updated information as a new demand model is finalized.  We literally can have several iterations in the model over the next few months – and dependent upon the eventual preferred alternative that will be developed as a result of the next round of stakeholder meetings and the eventual public hearing.

Once the preferred alternative is determined, that will dictate the next course for the following two levels of traffic and revenue studies. There may also be adjustments based on the revenue model as to what can be built with the available funding sources. Due to many factors, this is currently an unknown.

When the final “preferred alternative” for the MoPac South Project is determined, the Mobility Authority anticipates selling revenue bonds as part of the funding needed to complete the project.  With the official statement issued in connection with the sale, we will provide an updated and detailed “investment grade” T&R study, based on the specifics of the “preferred alternative” for the project.

The following are also key findings in the T&R forecast scenario as referenced above:

Key findings for the June 2015 T&R forecast scenarios:

  • The scenario with four express lanes with a downtown connection produces the highest congestion reduction and best use of the downtown connection.
  • The scenario with four express lanes without a downtown connection generates lower toll revenue than: (1) the four express lanes with a downtown connection, (2) the two express lanes with a downtown connection, and (3) the two express lanes without a downtown connection, because the four express lanes are more difficult to fill without the benefit of downtown connections.  The scenarios of four express lanes with a downtown connection, two express lanes with a downtown connection, and two express lanes without a downtown connection all generate similar toll revenue forecasts.
  • Both two express lane scenarios—with and without a downtown connection—would generate similar revenues as the four express lane scenario with a connection to downtown, but would have:
    • Higher toll rates than the four express lane scenarios; and
    • Longer peak period than the four express lane scenarios.

The higher toll rates and a longer peak period of congestion is a result of the limited express lane capacity available in a two lane configuration, as compared to a four lane configuration.

  • Please note that the June 2015 T&R forecasts do not include recent MoPac Expressway corridor improvements that have been added to the concepts through stakeholder agency input and public involvement. These include:
    • Direct Connector Ramps at US 290
    • New Collector Distributor near Loop 360
    • Extensive Ramp Improvements near William Cannon

Download: MoPac South Sketch-Level Traffic & Toll Revenue Study Preliminary Results - October 2014

Key changes between October 2014 and June 2015 T&R forecasts:

  • The October 2014 forecast only evaluated four express lanes from Slaughter to Cesar Chavez with direct connection ramps to downtown via Cesar Chavez. The June 2015 forecasts evaluated four scenarios:
    • Four express lanes with a downtown connection
    • Four express lanes without a downtown connection
    • Two express lanes with a downtown connection
    • Two express lanes without a downtown connection
  • The June 2015 forecasts included a minimum off-peak toll rate to cover toll collection costs.  The October 2014 forecasts used lower toll rates to maximize congestion reduction.

Traffic growth up to 2035 is based on travel demand model forecasts for both T&R forecasts. Long term growth rate beyond year 2035 was lower in the June 2015 forecasts.

Download: MoPac South Summary of Traffic and Revenue Trends by Scenario and Sketch-Level Traffic and Revenue Study Preliminary Results - June 2015

Stantec traffic memo

Memo developed by Stantec Corporation dated April 3, 2015.

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Austin, TX 78705

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Contact Us

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

Call (512) 996-9778
Email Us