On Oct. 15, a portion of the new northbound MoPac express lane opened to traffic between RM 2222 and Parmer Lane, offering commuters another option to relieve congestion.
Once completed, the MoPac Improvement Project will add one toll lane in both directions between Parmer and Cesar Chavez Street.
Traffic and revenue studies indicate the opened section of the project will have the lowest usage, but Central Texas Regional Mobility Authority officials expect this section to provide relief to drivers heading north in the afternoon peak period around Braker and Parmer lanes where traffic tends to bunch.
“People are going to be using more and more of this express lane to try to bypass all that backup,” said Jeff Dailey, the agency’s deputy executive director. “It will also provide traffic relief. If we can get 700 cars in that express lane, that will make a significant benefit to the general-purpose lanes.”
The entire project is about 80 percent complete as of mid-October, Dailey said. However, opening the remaining express lanes might not occur until spring, Mobility Authority Executive Director Mike Heiligenstein said.
“We’ll see how much pavement work they get done in [November],” he said. “I think it’s more like April when everything is substantially complete and we can open the rest of the northbound and all of the southbound.”
Once the project is complete, travel times will be reduced to 10-12 minutes in the express lane versus 30-40 minutes in the main lanes, Dailey said.
Drivers pay a toll to use the lane, and the rate is based on demand to keep the lane flowing at 45 mph.
“Our No. 1 goal is throughput,” said Greg Mack, Mobility Authority assistant director of information technology and toll systems. “We’re trying to get as many people through that corridor as possible.
“We keep the rate low so we can maximize the throughput. When the general-purpose lane [becomes congested] and the express lane becomes more valuable, we want to keep the express lane flowing, so we’ll start raising the rates to protect that capacity.”
Drivers only pay the rate they see displayed on the dynamic message sign at the entrance to the express lane even if the price changes while the vehicle is in the lane. The Mobility Authority will soon provide a way to look up the rate at the time of a transaction, Mack said.
The minimum toll rate is $0.25, and there is no maximum cost. Drivers without a toll tag pay a higher rate by mail.
Factors that determine the toll rate include the number of vehicles per hour, which the agency can track in each lane, as well as the speed of vehicles and number of vehicles entering the express lane, Mack said.
The Mobility Authority not only uses an algorithm to determine the toll rate but also staffers who operate the traffic-management center. Staffers monitor the lanes through seven cameras and 22 speed sensors in the open section. The entire project has 17 cameras and 59 speed radar sensors, Mack said.
“We look for any traffic incidents, any slowdowns, and that helps us determine if we should raise the price or not,” he said.
By early November, the agency expects to complete construction on the Steck Avenue bypass lane, which will allow drivers to avoid the intersection at MoPac and Steck.
Around the same time, traffic on the southbound MoPac main lanes near Cesar Chavez Street could shift to its permanent location over the express lane underpass.
Traffic on the northbound lanes in that area will shift atop the northbound express lane underpass by late November, and the third main lane over Lady Bird Lake will reopen for the first time since early 2016.
“It gets us back to the capacity we were at before construction started,” Heiligenstein said.26
The $204 million MoPac project was originally slated to open in fall 2015, but contractor CH2M ran into several issues that have delayed the project’s opening.
Heiligenstein said the agency has learned quite a few lessons from these issues, including the need for more oversight on complicated elements, such as the express lane underpasses that will connect to Cesar Chavez and Fifth streets.
CH2M recommended the underpasses as part of the design-build process, in which construction begins before the full design is completed.
“CH2M pretty drastically underestimated, particularly the underpasses, the cost,” he said. “I wouldn’t be surprised if [the cost] was an additional
$20 million-$30 million. It’s their responsibility.”