Transform 285/400 Interchange Improvement Project

Atlanta, USA

Transforming an Interchange to Ease Driver Travel

The Transform 285/400 Interchange Improvement Project is a design-build-finance project in Atlanta.

The project will improve 4.3 miles of I-285 from west of Roswell Rd. to east of Ashford Dunwoody Rd., and 6.2 miles along SR 400 from the Glenridge Connector to Spalding Dr. The improvements include eastbound and westbound collector-distributor lanes on I-285, and northbound and southbound collector-distributor lanes on SR 400. The new lanes will feed into the new interchange and NPC will construct 32 bridges throughout the project. The project also includes a diverging diamond interchange on Abernathy Rd. at SR 400 and widening Mount Vernon Highway bridge over SR 400.The project also includes pedestrian and bicycle improvements. The transformed interchange will ease travel for more than 400,000 drivers who use the interchange daily.

The work on the interchange will include girder as dance floor (the working area of a bridge deck) support with pre-assembled custom tables and preassembled custom soffit boxes. Then, 91-ft.-long Steel Girder straddle cap forms with interior Frami panels for cap shaping will be shipped. Double-faced 4-ft. tall Girder is used to support loads and minimize thru-tube depth from top of column. Frami is used as side forms for multi-span, straddle and hammerhead caps to allow full access for rebar installers. Also, Steel Girder Hammerhead forms will be shipped to the site to support A-frames, Gantry Beams, and Framax solutions for an offset cantilever hammerhead.

The project is conveniently located 35 minutes from Doka’s yard in Lawarenceville, GA and the standard material used is readily available. Access to Doka is easy for any quick site needs. The customer felt Doka went over and above when coming up with schemes and pricing for the bid phase. It was considered an advantage to have in-house Professional Engineering service in Doka. It’s important to point out that initially, Doka was not awarded the hammerhead caps. Later, through the design phase and then delivery, the customer decided that Doka’s design was better, and Doka was awarded the hammerheads with dancefloor support.

The Challenge
  • The highway bridges currently had existing in-use highways all around them, so there was minimal laydown area to work in. Additionally, tight rebar tolerances were part of the requirements.

The Solution
  • Framax was preferred as it is easily adjustable for different uses; it can cycle through structures as necessary. Equipment use is maximized at any given time – leaving the jobsite less cluttered. Dance floors are used for cap support to allow the installation of the massive amounts of rebar. The MF240 climbers allow the safe climbing of column panels. Additionally, the Doka preassembly of tables and custom soffit box-outs allow “off the truck installation” to minimize the needs of skilled labor or carpenters.

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Project data

Project duration
May 2016 - April 2020
North Perimeter Contractors, LLC

Building data

Construction method
Heavy Civil - Highway Bridge Substructure including multi-span caps, straddle caps, and hammerhead cap abutments.
Structure height
Bridge columns range up to 85 ft. to top of cap.