In the 1970s, songs about the open highway blasted from car radios all over the United States. Gordon Lightfoot sang about the “Carefree Highway,” the Doobie Brothers went “Rockin’ Down the Highway” and Willie Nelson longed to be “On the Road Again.” Today, those songs are a quaint reminder of the times before congestion overtook many of our highways.

Congestion sneaked up on us over several decades – the product of a growing population and increasing prosperity. The problem has been most pronounced in urban areas where residential and commercial development has made it increasingly difficult to expand roads built decades ago.

In Austin, MoPac is a prime example of the problem. Built in the 1970s, MoPac is now a parking lot during rush hour. There have been various proposals to expand the road over the past two decades, but most were met with stiff opposition based on concerns that additional right-of-way would be needed or that solutions would involve elevated structures.

At the same time, the growing transportation-funding crisis has severely limited options for improving the corridor. That led the Central Texas Regional Mobility Authority and the Texas Department of Transportation (TxDOT) to propose express lanes for the corridor.

Express lanes are the evolutionary offspring of high-occupancy vehicle (HOV) lanes. HOV lanes are designated for buses and vehicles carrying multiple people. HOV lanes were an early effort to increase mobility on constrained roadways in big cities like New York and Washington, D.C.

However, as HOV lanes proliferated around the country in the 1970s, they often failed to perform as envisioned. Many were underused. And enforcing the vehicle occupancy requirements became a huge challenge. In response, transportation officials began looking for a better option, and the concept of express lanes was born.

First implemented in California on State Route 91 (Riverside Freeway) in 1995, express lanes use demand-based tolling to manage traffic and ensure the lanes are always free flowing. Express lanes help ensure buses and vanpools arrive on time, making transit services more reliable. Since buses and vanpools don’t use all of the available capacity, individual drivers are also given the option to use the lanes if they are willing to pay a toll.

To ensure the lanes don’t become congested, resulting in slower travel speeds, the toll goes up or down real-time based on the number of drivers who choose to use the lanes.

Express lanes can be more expensive for drivers than traditional toll roads. They have to effectively manage traffic and prevent congestion. If the express lanes are underpriced during high-traffic times, the lanes quickly fill up, becoming as congested as the non-tolled lanes. As a result, they aren’t intended for everyday use.

Instead, they act as a safety valve for drivers who place a high value on time savings such as a parent who is late to pick up a child from daycare or an employee who is late for an important meeting. They also encourage carpooling because the cost of the toll can be split among several individuals and vanpools.

Express lanes have proven so successful that many communities, including Houston, Dallas, Salt Lake City, Denver and Miami, have transitioned their HOV lanes to express lanes in recent years. And another privately financed express lane project is currently underway on the Washington Beltway.

The MoPac Expressway is an excellent candidate for express lanes. It is a heavily congested corridor with very limited room to add capacity without negatively impacting nearby neighborhoods. Simply adding another regular lane would provide only temporary relief, would soon leave buses and vanpools stuck in traffic – just like they are today – and would diminish our goal of increased bus and vanpool use.

Also, in today’s difficult financial environment, express lanes would provide a source of funding to help underwrite construction of the project and fund future maintenance.

In 2010, the Mobility Authority and TxDOT, in partnership with the City of Austin and Capital Metro, launched the MoPac Improvement Project and reinitiated an environmental study to look at various options for improving MoPac. The study covers the stretch of MoPac between downtown Austin and Parmer Lane.

Over the past several months, the project team has been developing preliminary alternatives for the corridor and sharing those concepts with neighborhood groups and various stakeholders through a number of community meetings and open houses.

Using input received from the public and criteria defined at the onset of the study, the alternatives have been narrowed from 10 to four possible “build” options and one “no build” option. The “build” alternatives include adding one HOV lane in each direction; adding one express lane in each direction; adding one general purpose lane in each direction; and adding multiple lanes (general purpose and express).

These alternatives and the “no build” alternative are going through an extensive review process that takes several factors into account, including potential effects on the environment, historic properties and neighborhoods, implementation ability, right-of-way impacts and others.

Later this year and early next, the public will be invited to participate in additional meetings, workshops and open houses. All of the “build” alternatives would include noise mitigation where determined reasonable and feasible, most likely in the form of sound walls. Once the noise analysis is complete, workshops will be scheduled with neighborhoods where sound walls are warranted.

Ultimately, under federal and state noise mitigation requirements, owners of properties adjacent to the proposed sound walls will vote to decide whether or not the walls are built.

In addition to the sound wall workshops, a Context Sensitive Design process is being undertaken with the community to develop roadway design and landscape concepts that reflect the community’s vision for the project.

Meanwhile, meetings and discussions are continuing with representatives from the bicycle community to discuss priorities for bike, pedestrian and trail enhancements in the corridor. And a National Historic Preservation Act process is also underway to identify historic properties in the corridor and determine options for avoiding, minimizing or mitigating any adverse effects the project may have.

At the conclusion of all these processes and the environmental study, planners will present a recommended alternative to the public and the Federal Highway Administration (FHWA) in spring 2012. The FHWA will ultimately decide if improvements will be made to the corridor, or if additional studies are needed.

We will then know if express lanes are the right option for the corridor. If express lanes become the recommended alternative, construction could be underway by 2013.

For more information, visit www.mopacexpress.com.