FREQUENTLY ASKED QUESTIONS

The I-526 @ Long Point Road Interchange Improvements project was identified as a priority through the I-526 Lowcountry Corridor (LCC) EAST Planning and Environmental Linkages (PEL) study. The purpose of the proposed project is to improve the operations of the I-526/Long Point Road interchange and I-526 mainline and reduce operational conflicts between port-related and local traffic.

This interchange was identified as needing improvements, and four initial high-level concepts for the interchange were shown at the fall 2021 public information meeting for the I-526 LCC EAST PEL Study. Based on public input, the project team conducted engineering analyses to identify six total options, known as the range of alternatives. Preliminary traffic analysis indicated that Alternative 4: Single Point Urban Interchange (SPUI) and Alternative 5: Flyover would not improve the traffic operations performance significantly enough to meet the purpose and need of the project, so the range of alternatives was narrowed as follows:

• Alternative 1: Improved Existing Ramps

• Alternative 2: New Port Access Ramps with Improved Existing Ramps

• Alternative 3: Diverging Diamond Interchange (DDI)

• Alternative 6: New Port Access Ramps with Diverging Diamond Interchange (DDI)

The alternatives were evaluated through a three-step process of engineering and environmental studies to identify the recommended preferred alternative:

Step 1: Purpose and Need (Traffic Analysis and Engineering)

Step 2: Purpose and Need (Detailed Traffic Modeling), Engineering, and project goals

Step 3: Purpose and Need (Traffic Analysis), Engineering, Natural Resources, Community and Built Environment, project goals

Greater detail in analysis came with each level of evaluation. At the same time, the total number of alternatives decreased as those that were lowest performing were eliminated. This screening process helped SCDOT arrive at the Recommended Preferred Alternative. The Recommended Preferred Alternative was presented to the public for feedback at the public hearing held on May 2, 2023, and is available on the public hearing webpage www.526LCCLongPoint.com/publichearing.

The National Environmental Policy Act (NEPA) requires federal agencies, like the Federal Highway Administration (FHWA), to consider the impacts of their decisions on the natural environment and to include the public in the decision-making process. An Environmental Assessment (EA) is being prepared for the I-526 @ Long Point Road Interchange Improvements project. The EA will outline the development process of the proposed project, identify reasonable alternatives, analyze the potential environmental impacts resulting from the reasonable alternatives, and demonstrate compliance with other applicable environmental laws and executive orders. The results of all engineering and environmental studies, including all environmental impacts, are published within the EA. The draft EA was made available to the public during the public hearing and associated public comment period and remains on the environmental assessment webpage here (www.526LCCLongPoint.com/environmentalassessment).

The average daily number of vehicles, including cars and commercial vehicles, driving through the I-526/Long Point Road interchange is expected to grow 66% by 2050. 13,000 more truck trips per day are anticipated on I-526 west of the Long Point Road interchange by 2050. A portion of the increased truck traffic on Long Point Road is associated with growth at the Wando Welch Terminal traffic. Other increased truck trips in the area may be attributed to population growth and increases in home deliveries and ecommerce.

The SC Ports freight forecasts consider the opening of other facilities in the region (including the new Leatherman facilities) and the types of cargo served by each facility (rail, truck containers, bulk materials, etc). Considering all these factors, the 30-year growth at the Wando Welch Terminal assumes continued growth to approximately 2027, a shift of some truck traffic to the Leatherman facility in 2028, and then continued growth at Wando Welch through approximately 2039. From 2039 to 2050, the Port’s planned capacity is reached, and truck operations continue at a constant level through 2050. This growth, coupled with shifts in delivery patterns, are included in the truck forecasts used in this project for the 2050 design year. The existing interchange cannot handle this volume or mix of vehicles.

SC Ports continues to monitor and optimize operational performance of the Wando Welch Terminal and modifies operations to accommodate the demand for freight movements. With the introduction of barge service and near-dock rail service in North Charleston, some diversion of cargo ships will occur, reducing the growth of port-related truck traffic in this project area.

Alternatives 3 and 6 propose constructing a diverging diamond interchange (DDI). A DDI allows free-flowing turns when entering and exiting an interstate, eliminating the left turn against oncoming traffic, and limiting the number of traffic signal phases so vehicles do not have to wait as long. The graphics below demonstrate how vehicle movements would work for those traveling from south to north and north to south. A typical DDI has the two signals as shown. However, due to the traffic volumes and high number of turn movements being processed at Long Point Road, these proposed DDI improvements would actually be composed of five signals. Three of them work together at the left (southern signal) and two at the right (northern signal).

A total of four noise barrier locations were identified as feasible and reasonable for the Recommended Preferred Alternative. This includes proposed noise walls north of I-526 and west of Long Point Road between the Wando River bridge and Belle Hall Parkway, south of I-526 between the Wando River bridge and Ridge Road, south of I-526 and east of Long Point Road between Lone Tree Drive and the bridge at Hobcaw Creek, and north of I-526 and east of Long Point Road between Long Point Road and the bridge at Hobcaw Creek. A map of the proposed noise walls can be found online at www.526lcclongpoint.com/publichearing/#noisewall.

To determine the proposed noise wall locations, a traffic noise analysis was conducted for the study area and completed in accordance with federal and state policies and requirements. Noise-sensitive sites such as residences, churches, schools, and recreational areas were analyzed.

The project team established a baseline of existing traffic noise using the Federal Highway Administration’s traffic noise model. This analysis determined that current noise levels approach or exceed the noise abatement criteria for approximately one third of the receptors in the study area. The Recommended Preferred Alternative would result in noise impacts associated with modifying the existing I-526/Long Point Road interchange. However, those impacts would vary depending on the proximity to the project.

Per 23 CFR 772.13(c) and the SCDOT Traffic Noise Abatement Policy, noise abatement measures must be considered to reduce or eliminate noise levels to impacted receivers (66 dB(A)). All four noise barrier locations have been recommended as noise mitigation for the Recommended Preferred Alternative. A final decision on noise wall construction will be made upon completion of the project’s final design and the public involvement process. More detailed information regarding the noise analysis can be found in Appendix E of the Environmental Assessment (www.526lcclongpoint.com/environmentalassessment).

For the first step in the process, SCDOT experts go to homes, churches, businesses, or other places that may be affected by a proposed highway project and use special equipment to monitor existing noise.

Next, complex computer modeling is used to predict expected noise changes at these locations once the road is built and traffic increases.

Then, it must be determined which noise-sensitive locations were permitted before the Date of Public Knowledge and, therefore, are eligible for noise reduction.

If the anticipated noise increase is MORE than the level defined by SCDOT policy, we begin to consider possible ways to reduce the noise, such as with noise walls and earth berms, at all eligible locations.

Before final designs are created for the proposed noise walls, those who would directly benefit from the walls will have the opportunity to vote if they are in support of the noise walls’ construction. At this time, we know the recommended noise walls have an average height of 24 feet. A public hearing exhibit on noise walls (www.526lcclongpoint.com/publichearing/#noisewall) demonstrated just one idea as to what the walls could look like at varying viewpoints throughout the project. The design you see on the website is an artist rendering and does not necessarily reflect the actual aesthetic of the noise walls.