August 14, 2015

The Conway Bypass: Ahead of Schedule & Under Budget

Aerial image of the Conway Bypass in Myrtle Beach, South Carolina designed by Davis & Floyd in 1994.

The Conway Bypass was finished seven months ahead of schedule and under budget.

In 1994, the State of South Carolina sought a design-build team for the Conway Bypass, also known as South Carolina Highway 22 and the Veterans Highway. In partnership with Fluor Infrastructure Group in Greenville, South Carolina, Davis & Floyd’s transportation engineering expertise helped win proposal selection by the South Carolina Department of Transportation (SCDOT) in 1998 with construction to be completed by 2002.

The 22-mile route featured engineering designs for a total of 57 miles of roadway that included six interchanges—at US 501, SC 319, US 701, SC 905, SC 90, and US 17—in three different configurations: partial cloverleafs, diamonds, and an elevated trumpet interlaced with a side road and frontage road. The roadway also required seven grade separations, and 17 AASHTO-girder grade-separation bridges. Prior to construction, Davis & Floyd also coordinated bridge designs by The LPA Group, Inc. and Figg Engineers, Inc., handled environmental permitting, and performed all construction survey work.

During the lead-up to the project, Davis & Floyd organized a stakeholders “field walk” among SCDOT, engineers, and regulatory and resource agencies, which facilitated the group to agreeing to reclassify many areas as uplands instead of wetlands. The original design featured 10 miles of wetland bridges, making the project financially prohibitive. But by eliminating 5 miles of bridges (and saving $60 million off the bat), Davis & Floyd was able to finish ahead of schedule and under budget and the bridges that remained were shifted or segmented to minimize the impact to wetlands and other environmentally sensitive areas.

With the reduction of project cost by bridge elimination in areas of “marginal production wetlands,” Davis & Floyd was able to make a lump sum (from project savings to mitigation fund) available to regulatory agencies in order to acquire sites for preservation and conservation.

Davis & Floyd also modified the plan for a proposed development of an 800-acre mitigation site, including restoration of bottom lands to hardwood, replanting of higher ground areas with mixed hardwoods, removal of roadway and ditches, and establishment of eight 5-acre test tracts. The area was monitored on a continuing basis for four years by Davis & Floyd, culminating in a study report of improved methods to re-establish this and similar tracts to their original status—valuable expertise for application on future projects.

As with other large-scope projects, Davis & Floyd was able to conduct recurring environmental compliance audits, participate in status meetings, monitor compliance with wildlife crossing requirements, and acquire land disturbance permits and (modified) wetland permits. Construction layouts, staking, controls and monumentation were also under the purview of Davis & Floyd—including daily communications with on-the-ground contractors and the creation of a 3D model which allowed for project grading without physical staking.

When all was said and done, the Conway Bypass was finished seven months ahead of schedule and under budget, thanks to initiatives undertaken by Davis & Floyd. When the construction was completed, it was the largest design-build project completed by SCDOT and the $385,000,000 project received numerous engineering excellence awards for its success.