Neel-Schaffer delivers expedited interchange for MDOT
Neel-Schaffer was selected by the Mississippi Department of Transportation to provide complete design and construction engineering services for a new interchange on I-55 near Canton to serve the new Nissan Motor Company manufacturing plant.
The new interchange, together with a frontage road and a connection with US 51, was part of the infrastructure incentive package offered by the state to the motor company. Because of the sensitive nature of negotiations with Nissan, Neel-Schaffer provided services under a confidentiality agreement with MDOT.
MDOT chose Neel-Schaffer because of the firm’s demonstrated ability to meet demanding schedules. Design work began in September 2000 and the project was advertised for bids in December of the same year. To expedite the design, weekly meetings were scheduled with decision makers at MDOT and Neel-Schaffer to address design issues as they arose.
Project elements included a traditional cloverleaf interchange with parallel collector-distributor (CD) roads on both sides of the interstate. The CD roads were included to allow anticipated heavy truck traffic to exit the interstate safely.
Because of the anticipated heavy truck traffic and the presence of expansive clay, or high volume change (HVC) soils, the specifications provided for removal of HVC material (in cut areas) in or above the design soil prism. The top 6 inches of the subgrade was lime treated and covered with a 6-inch layer of crushed limestone and a 4-inch asphalt drainage layer that drops to an underdrain system located beyond the lime treated subgrade.
The specifications further provided that all traffic areas be capped with an asphalt base course. Six bridges were included in the design effort:
- Twin prestressed concrete AASHTO bulb T beam bridges at cloverleaf
- Twin prestressed concrete AASHTO Type III beam bridges over CN/IC Railroad
- Prestressed concrete beam bridges over Soldier Colony Road on both C-D roads
Subsequently, MDOT chose Neel-Schaffer to set up a project engineer’s office to provide construction engineering and inspection services.