Austin, Texas — The Texas Department of Transportation (TxDOT) selected planning, engineering and program management firm Lockwood, Andrews & Newnam, Inc. (LAN) as lead designer for MoPac Expressway improvements at Slaughter Lane and La Crosse Avenue in southwest Austin. The project includes the first Diverging Diamond Interchange in the city.

The MoPac Expressway intersections at Slaughter Lane and La Crosse Avenue were originally constructed in 1992 and have grown increasingly congested over the years. Traffic congestion at these intersections has created operational problems, causing travel delays and adversely affecting access and mobility.

The 1.95 mile project will include the construction of main lanes on the MoPac Expressway and grade separated interchanges at Lacrosse Avenue and at Slaughter Lane. The MoPac/Slaughter interchange will be constructed as a Diverging Diamond Interchange (DDI) – the first in the City of Austin – to handle the large volume of left turning traffic while the MoPac/La Crosse Avenue Interchange will be constructed as a diamond interchange which is best suited for the traffic at that location.

“The proposed improvements at these two intersections will significantly reduce delays that the traveling public currently experience along and across Mopac,” said Terry McCoy, P.E., Deputy District Engineer of TxDOT Austin District.

The improvements will include retaining walls at the bridges, a storm sewer system, traffic signals and new pavement, striping and signing throughout the project limits. The MoPac/ Slaughter DDI will be illuminated and traffic signals will be interconnected with other Slaughter signals nearby to move traffic efficiently. TxDOT and the City of Austin are working together to provide connectivity on a local hike and bike shared use path. Additionally, the DDI will provide bike lanes and ADA compatible pedestrian facilities.

To protect the environmentally sensitive Edwards Aquifer Recharge Zone, the project team will incorporate both temporary and permanent erosion control and water quality measures into the design. During construction, sediment control fencing, construction exits, rock filter dams, inlet filters and other methods will be incorporated. Once constructed, the project will include permanent water quality features such as water quality basins, hazardous material traps and permanent vegetative filter strips.

The approximately $35 million project is expected to be designed by the fall of 2015 and will be ready to go to construction once funding becomes available.