Davis & Floyd participated on a team that is studying the 8-mile segment of I-526 between US 52 / Rivers Avenue in North Charleston and US 17 / Savannah Highway in West Ashley, including the I-26 & I-526 interchange. This corridor experiences high traffic volumes with considerable congestion during the weekday AM and PM peak periods. Future traffic volumes are expected to increase considerably with several large developments planned in the area. Davis & Floyd was tasked with all field surveys and hydrology/hydraulic design to widen I-526 from Leeds Avenue to the US 52 / Rivers Avenue. During the initial contract execution, a Contract Modification was added to extend the limits to US 17 (Savannah Highway).

The I-526 corridor improvement project includes adding a travel lane in each direction along I-526 and six interchange improvements. The field surveys included setting of project controls, coordination with aerial survey subconsultants, best fit of existing roadway alignments, courthouse research, property monument locations, property strip maps, supplemental 2D/3D mapping, drainage inlet/outfall surveys, drainage structure surveys, sanitary sewer surveys, wetlands surveys, geotechnical boring surveys, existing bridge verifications, railroad coordination/surveys, and traffic control coordination for interstate surveys.

Hydrologic and hydraulic analysis of corridor includes:

  • Field investigation to inventory location and condition of existing cross lines, determine watershed boundaries, evaluate existing structure performance, and evaluate stability and capacity of drainage outfalls
  • Data collection necessary to perform hydrologic and hydraulic analysis and design including stream gaging of Filbin and Bulls Creeks for model calibration
  • Watershed regional hydrologic and hydraulic analysis of five major watersheds, 26 cross line pipe/culverts, pre- and post-construction flows, and detention analysis, among others
  • 2D bridge hydraulic analysis of the General William C. Westmoreland Bridge over the Ashley River


  • Field Surveys
  • Hydrology & Hydraulic Design