The managed lanes carry commuters along a 12 mile stretch of the Katy Freeway. There's one lane in each direction.
They're used as HOV and transit lanes, and they also serve as a toll road for single-occupant vehicles. The amount of the toll depends on traffic congestion.
Texas A&M professor Mark Burris says it's a unique system.
"There's a handful in the U.S. that have separated lanes that are toll lanes in the middle of general purpose lanes, or non-toll lanes."
Burris says that's one of the reasons they chose the freeway for a Texas Transportation Institute study. They want to find out if managed lanes will work in other parts of the state. TxDOT will then use the information for planning future projects.
"We can learn a lot from what's worked, and maybe find out what hasn't worked and what we can improve on, just from the sheer size of it and the number of vehicles moved every day."
The Harris County Toll Road Authority says when the managed lanes opened three years ago, about 400,000 drivers a month paid a toll to use the lanes. That number has now risen to about 970,000 per month.
"When we asked people how much they'd be willing to pay to use these lanes, that gives us an indication how valuable the lanes are to them and how valuable their time is, because using these lanes saves them travel time."
Burris says they gathering other information in their study, such as the number of crashes, maintenance costs, and ease of access. To participate, visit the Katy Freeway Managed Lanes survey.