Advisory committee declines to accept final William Hilton Parkway corridor report; forwards findings to council

The William Hilton Parkway Gateway Corridor Independent Review Advisory Committee voted Wednesday not to accept the final corridor study prepared for the town, with committee members citing concerns about modeling transparency, bridge work and timing. Staff said the final report will be forwarded to town council for consideration in September.

The consultant team, led in the meeting by Nate and traffic planner Michelle Romine, summarized work completed under the SCDOT-modified preferred "alternative 1," including a 2045 traffic forecast of about 2,045 vehicles and downstream evaluations beyond Gumtree Road and along Cross Island Parkway toward Sea Pines Circle. "After reviewing the findings and discussion with the South Carolina Department of Transportation, we were directed by the town of Hilton Head Island to pursue ... the SCDOT modified recommended preferred," Romine said during the presentation.

The study presented two mitigation options for intersections east of Gumtree. Option A minimizes physical impacts and recommends widening at a single intersection at US 278 and Pembroke Drive (including dual northbound left-turn lanes) and retaining a roundabout at Sea Pine Circle but expanding it to two circulating lanes with right-turn bypasses; the team estimated the Pembroke work at a preliminary probable cost of $750,000 with a roughly four-month construction window and said Sea Pine Circle work could take about eight months. Option B considered a wider approach: extending a six-lane section past Pembroke (tapering to four lanes near Central Avenue), additional signalization and right-of-way needs; preliminary costs cited included $3,000,000 for the major widening and $6,000,000 and 12 months to convert Sea Pine Circle to a signalized intersection.

Consultants said the primary benefit of Options A and B is reducing long queues between Gumtree and Pembroke and improving local intersection performance; they emphasized that neither option provides large corridor-wide travel-time gains between Moss Creek and Indigo Run compared with the modified alternative 1. The team reported projected maximum queues of over 1,000 feet at Jarvis Park/Wilborn under some scenarios and warned the existing roundabout at Palmetto Bay Road and Sea Pine Circle could fail in both AM and PM peak hours without mitigation.

Committee members questioned the study's modeling approach and public transparency. Committee member Diedrich said the public and some committee members had not seen interactive, corridor-level simulation iterations and expressed frustration with decisions made before the study was complete: "I don't know whether to laugh or to cry ... the town decided to go ahead after that work, that July 28 meeting, with a study that wasn't completed, and sort of pulling the rug from others," he said. Consultants responded that they performed comprehensive, calibrated analyses and that interactive VISIM-style demonstrations are laborious and limited by software access, but that internal iterations had been performed by their team.

During public comment, Melinda Tunner urged retaining traffic circles as part of the island's character and opposed expanding William Hilton Parkway from four to six lanes, saying the traffic-flow gains would not justify added impervious surface. "Traffic circles are part of the island charm," Tunner said, and she asked when Beaufort County is expected to vote on the municipal‑consent MOA and how the town will keep the public informed as the project proceeds.

At the meeting's close, a committee member moved to accept the final consultant report; after discussion and additional remarks about bridge condition, seismic retrofit questions and the town's internal modeling capacity, the motion failed and the committee declined to recommend acceptance. Presenters and staff noted the report will still be presented to town council in September and that town council had already acted on related items earlier in the process.

The committee adjourned with no new business. Staff said they would provide the study materials to other corridor‑plan consultants and prepare for the town council presentation next month.