The MemFix4 project in Memphis, TN used the CMGC (Construction Manager/General Contractor) delivery method to widen I-240 and replace and/or rehabilitate four structures while minimizing impacts to interstate traffic and the Norfolk Southern Railroad (NSR). It is Tennessee’s second-ever project to be completed using this delivery method.
Benesch completed a technical study for MemFix4 in 2015 to define the project’s scope and determine viability of the CMGC delivery method. In September 2016, design work began and Kiewit Infrastructure South Co. was selected as Construction Manager. The CMGC Team (TDOT, Benesch and Kiewit) worked collaboratively during design and continued their partnership throughout the project’s construction. CMGC delivery provided ample opportunity for implementing highly complex Accelerated Bridge Construction (ABC) techniques while yielding change orders at a significantly lower level than the industry average—especially on a project of this size and complexity.
In all, 18 months were cut from this $54 million project’s construction schedule. Design was completed in October 2017; lane closures first occurred in January 2018, with all original lanes open by the third weekend of December—less than 12 months later. Traditional delivery methods could have required three years to construct MemFix4. Through ABC and other innovative techniques, the CMGC team completed all construction activity in just 18 months.
With 180,000 vehicles and 20 freight trains passing through the corridor each day, the widened I-240 and associated structures are a boon to the travelling public. The corridor’s once aging infrastructure is now a showcase for innovative structural engineering techniques. With the added benefits of improved seismic performance and long-term flexibility, the project has set the stage for continued growth along I-240.
Innovative Delivery Methods
New two-span steel girder bridges for east and westbound Poplar Avenue were constructed off-site at bridge farms and then rolled and lifted into place during two weekend roadway closures. Using modular superstructures built off-site shaved several years’ worth of lane closures down to less than 120 hours.
Railroad Bridge Slide-Ins
Two new 2.2-million-pound Norfolk Southern bridge superstructure sections were slid 35 feet into place, one track at a time—an engineering first on an active railroad bridge in Tennessee. These superstructures were also used as part of the temporary shoofly structure to maintain train traffic during construction. In order to always keep one track open, the new superstructure was slid in one half at a time to its permanent position.
The Park Avenue bridge was preserved using novel foundation retrofit design. Finite element modeling fine tuned the bridge’s seismic behavior, which optimized the use of micropile retrofits and minimized materials and cost.