Interstate 526, Interstate 26, and local roads meet near Charleston, South Carolina. The purpose of this project was to provide engineering services for alternative steel and prestressed concrete designs for an interchange consisting of twin overpass structures over existing Interstate 26, an on-grade local street, a local stream, and a Southern Railway Track. This was accomplished using seven direct connecting elevated ramp structures to connect these complex urban freeways.

Modjeski and Masters, Inc., provided the following engineering services:

• Set structure end stations based on geotechnical studies performed by another consultant,

• Established span lengths and developed preliminary plans, including geotechnical studies and seismic criteria,

• Prepared final designs, contract plans, specifications, and cost estimates for the interchange,

• Attended prebid conferences and responded to questions, and

• Performed construction consultation services including checking shop drawings.