Sanibel Roundabout Debate: Traffic Studies, Seasonal Congestion and the Future of Island Roads
Last Updated: November 12, 2026
Last updated: November 12, 2026
Anyone who has experienced Sanibel's winter traffic knows that the island can feel like two very different places depending on the time of year.
During the quieter summer months, a drive along Periwinkle Way may be relatively easy. During peak winter season, the same journey can involve long lines of vehicles, particularly near the intersection of Periwinkle Way, Causeway Boulevard and Lindgren Boulevard.
For years, residents, business owners, commuters and city officials have debated how to improve traffic flow at this critical intersection. Now, a proposed roundabout has brought that discussion into sharper focus.
But is the four-way stop the primary cause of Sanibel's congestion? Would a roundabout improve traffic flow without creating new problems elsewhere? And how should the city account for seasonal population changes, future development on Captiva and the limited capacity of the Sanibel Causeway?
These questions affect more than driving convenience. They touch on Sanibel's economy, workforce, quality of life, environmental character and long-term real estate appeal.
What Is Being Proposed at the Periwinkle Way Intersection?
The City of Sanibel has been evaluating the possibility of replacing the existing four-way stop at Periwinkle Way, Causeway Boulevard and Lindgren Boulevard with a roundabout.
Unlike a traditional intersection controlled by stop signs or traffic signals, a roundabout allows vehicles to enter a circular roadway after yielding to circulating traffic.
Properly designed roundabouts can reduce certain types of collisions and improve traffic flow by limiting complete stops.
However, their performance depends on traffic volumes, the balance of traffic entering from different directions, pedestrian and bicycle crossings, and congestion on the roads leading away from the intersection.
Sanibel's situation is unusual because Causeway Boulevard connects the island to its only vehicular route to the mainland.
Will Sanibel Residents Vote on the Roundabout?
On September 14, 2026, Sanibel City Council adopted a resolution calling for an advisory referendum regarding construction of a roundabout at this intersection.
The referendum is intended to obtain public input before Council makes a final decision.
An advisory vote does not itself authorize construction, approve a final design, or appropriate construction funding.
Residents should consult the city's official election notices for the final ballot details and voting information.
Source: City of Sanibel Resolution 26-026a
Why Has Sanibel's Four-Way Stop Been Studied for So Long?
Traffic congestion at Sanibel's main entrance is not a new problem.
The island has been evaluating traffic flow, Causeway capacity and intersection improvements for decades.
1997: Regional Bridge and Toll Traffic Research
A University of South Florida Center for Urban Transportation Research study examined traffic conditions involving the Sanibel Causeway and other Lee County bridges.
This early research established that bridge access, traffic patterns and roadway capacity were already subjects of regional transportation analysis.
2015: Seasonal Traffic Management Proposals
During the 2015 winter season, then-Sanibel Mayor Kevin Ruane discussed approximately 13,000 vehicles entering the island daily during peak periods.
Suggestions for improving traffic included staggered employee schedules, carpooling, traffic cameras, improved traveler information and encouraging visitors to avoid concentrated departure times.
These approaches focused on managing traffic demand rather than relying entirely on roadway construction.
2017: Lee County Metropolitan Planning Organization Roundabout Study
A regional roundabout feasibility study evaluated multiple potential locations, including the intersection of Periwinkle Way, Causeway Boulevard and Lindgren Boulevard.
The study examined traffic operations and projected future conditions.
An important finding was that improving movement through the intersection would not necessarily eliminate congestion on the connecting roadways.
The study also examined northbound traffic merging toward the Causeway and considered relocating the merge farther north.
That distinction remains central to the current debate: moving vehicles through an intersection more efficiently does not automatically increase the capacity of the roadway beyond it.
2024: Updated Sanibel Intersection Evaluation
In 2024, Sanibel retained Kimley-Horn and Associates to evaluate the intersection using updated traffic counts, turning movements, seasonal adjustments, previous studies and public feedback.
The resulting work included conceptual recommendations for intersection improvements and roundabout configurations.
The city's website provides simulated roundabout views and related project information.
View the City's Periwinkle Way and Causeway Boulevard Intersection Study
2025–2026: Causeway Capacity and Additional Design Work
The city subsequently investigated whether the existing Causeway bridges could accommodate three travel lanes, potentially allowing two outbound lanes during busy departure periods.
The feasibility review identified substantial safety and engineering concerns with simply restriping the existing bridges.
Additional roundabout design work and topographical evaluations were also considered during 2026.
Together, these studies reflect an important reality: Sanibel's transportation challenge extends beyond a single intersection.
High Season vs. Low Season: How Many People Are Actually Using Sanibel's Roads?
One of the most important considerations in the roundabout debate is the dramatic difference between Sanibel's permanent population and the number of people using the island during peak tourist season.
According to the U.S. Census Bureau, Sanibel's estimated resident population was 6,303 in July 2025.
But this does not mean that exactly 6,303 residents are physically present throughout the year.
Sanibel has many seasonal homeowners who maintain Florida as their legal primary residence but spend significant portions of the year elsewhere. Other property owners consider Sanibel a second-home or vacation destination.
Although the six-month-and-one-day guideline is frequently discussed in connection with residency and taxation, Florida's homestead exemption does not impose a universal 183-day physical occupancy requirement.
During winter, seasonal homeowners are joined by vacation renters, hotel guests, day visitors and employees commuting from mainland communities.
Could 40,000 People Be on Sanibel and Captiva During Peak Season?
Historical estimates suggest that the number of people present on the islands during peak season can be several times Sanibel's permanent population.
A historical Sanibel Island profile published in Islander Magazine provided the following estimates:
Population GroupHistorical EstimateYear-round residents5,500Additional winter residents12,000Daily commuting employees6,000Daily visitors10,000–15,000Estimated combined total33,500–38,500
Separately, the Sanibel-Captiva Chamber of Commerce has historically estimated that as many as 40,000 people could be on Sanibel and Captiva during peak season.
These figures are historical estimates, not verified 2026 population counts. The detailed Islander breakdown concerns Sanibel, while the Chamber estimate includes both islands. Some categories may overlap, and post-Hurricane Ian conditions have changed.
Nevertheless, they illustrate why a city with a relatively small permanent population can experience substantial seasonal transportation demands.
Actual Causeway Vehicle Counts Show the Seasonal Difference
Official Causeway traffic records provide a more direct measurement of how travel demand changes during the year.
In March 2025, approximately 296,471 vehicles entered Sanibel.
In August 2025, approximately 215,005 vehicles entered the island.
That represents approximately 81,466 additional inbound vehicle crossings in March, nearly 38% more than August.
These are monthly vehicle crossings, not counts of unique people. They include repeated trips by residents, workers and visitors.
The figures also do not reveal the precise number of vehicles arriving during the busiest hour, which is especially important when evaluating intersection design.
Still, they demonstrate how significantly seasonal demand can change while the Causeway's physical capacity remains essentially the same.
What Are the Advantages and Disadvantages of High Season?
Sanibel's winter and spring season brings important economic and lifestyle benefits.
Restaurants, shops, resorts, vacation rentals and recreational businesses benefit from seasonal demand. Community events and social activities increase, and cooler weather attracts visitors and seasonal homeowners.
However, the same influx can bring longer driving times, crowded beach parking, busy restaurants and increased pressure on infrastructure.
For employees commuting from the mainland, winter traffic can turn an otherwise manageable trip into a lengthy daily commitment.
What Changes During Low Season?
Summer and early fall generally bring lighter traffic, quieter beaches, easier parking and a more relaxed pace.
Year-round residents may particularly appreciate the opportunity to enjoy local businesses and recreational areas without peak-season crowds.
However, the quieter months also bring hotter temperatures, higher humidity, hurricane-season considerations and reduced activity at some businesses.
Some restaurants and shops may adjust their hours, and vacation rental demand often follows different seasonal patterns.
Neither season is inherently preferable. Each offers a different version of island living.
The transportation question is how to design infrastructure that functions safely and efficiently during both.
The Overlooked Traffic Factor: Employees Commuting to Sanibel
Sanibel's transportation network supports far more than residents and tourists.
The island depends on employees working in hospitality, restaurants, retail, healthcare, real estate, construction, property management, maintenance, public safety and other essential services.
Many live in Fort Myers, Cape Coral and surrounding mainland communities.
Sanibel's 2024 Long-Term Recovery Plan reported that approximately 86% of jobs located in the city were held by people living outside Sanibel in 2020.
That is a significant consideration when discussing Causeway congestion.
Workers often have fixed schedules. Unlike vacationers, they may have little flexibility to avoid the busiest commuting periods.
During high season, employees share the road with seasonal homeowners, day visitors, vacation renters, delivery vehicles and contractors.
During low season, workforce commuting continues even when tourist activity declines.
Could Workforce Housing Reduce Traffic Demand?
Workforce housing is sometimes discussed separately from transportation, but the two issues are closely connected.
When employees can afford to live near their workplaces, some daily commuting trips may be reduced.
Sanibel's Community Housing and Resources organization provides below-market-rate housing opportunities that help address the challenge of maintaining a local workforce.
Workforce housing alone would not eliminate seasonal congestion, and not every employee would choose or qualify to live on the island.
However, it deserves consideration alongside roadway engineering, employee transportation programs and other traffic-management strategies.
The Bigger Challenge: Sanibel Has Only One Vehicular Route to the Mainland
The Sanibel Causeway is both the island's primary access route and a fundamental constraint on its transportation system.
During busy periods, traffic leaving Sanibel must ultimately move through the Causeway corridor.
Even if a roundabout reduces delays at the Periwinkle Way intersection, it cannot independently create additional bridge capacity.
This is particularly important when outbound traffic begins to back up.
If vehicles cannot move away from the intersection quickly enough, queues can extend upstream and interfere with otherwise efficient traffic movement.
Could a Roundabout Simply Move the Traffic Jam?
That is one of the most important questions raised by the proposal.
A roundabout may allow vehicles to enter the intersection more continuously than a four-way stop.
However, if the Causeway is already operating near capacity, vehicles may encounter congestion immediately after leaving the roundabout.
Under some traffic conditions, queues could extend back toward or into the circular intersection.
Another consideration is whether heavy traffic from one direction could make it difficult for vehicles from other approaches to find suitable entry gaps.
Neither outcome should be assumed to occur automatically. Both should be evaluated using realistic peak-season traffic models.
The meaningful measurement is not simply how quickly vehicles pass through the intersection.
It is how long the complete journey takes, particularly from the western portions of Sanibel and Captiva to the mainland.
How Much Public Money Has Been Authorized for Sanibel Traffic Studies?
City Council records document several recent expenditures and funding decisions related to traffic engineering.
In May 2024, the city approved $164,465 for the Periwinkle Way, Causeway Boulevard and Lindgren Boulevard intersection study.
In June 2025, Council approved $29,200 for a feasibility study examining whether three travel lanes could be accommodated on the existing Causeway bridges.
These two directly related studies represent $193,665 in approved funding.
The city also authorized $24,326 for a separate speed limit study, bringing the combined amount for those three transportation studies to $217,991.
During 2026, Council considered additional roundabout engineering work, including a topographical survey and more comprehensive design evaluation, with outside funding from the Lee County Metropolitan Planning Organization.
These figures must be distinguished carefully. Approved budgets, proposed engineering costs, grant awards and actual consultant payments are not necessarily the same.
A complete accounting would require reviewing final invoices, contract amendments and any additional expenditures through the current date.
What Should Residents Expect From the Studies?
Publicly funded traffic studies can provide valuable information, even when a particular proposal is not ultimately constructed.
However, residents should be able to understand what each study evaluated, what conclusions it reached and how those conclusions inform the next decision.
Useful questions include whether the studies measure complete travel times, examine seasonal extremes, evaluate emergency access and account for future development.
The public cost of engineering work is relevant, but so is the quality of the information obtained.
Could Increased Development at South Seas Add to Sanibel's Traffic Challenges?
Although South Seas Resort is located on Captiva, most vehicles traveling between Captiva and the mainland must pass through Sanibel.
That makes future development on Captiva directly relevant to Sanibel's long-term transportation planning.
What Has Been Approved at South Seas?
In August 2025, Lee County commissioners approved rezoning for approximately 120.5 acres at South Seas Resort, allowing a development program totaling 628 hotel and condominium units.
The approval has generated debate about development density, infrastructure, environmental impacts, emergency evacuation and traffic.
The approved development framework should not be confused with the number of accommodations already constructed or occupied.
Additional accommodations may generate new trips by guests, employees, service providers, contractors and delivery vehicles.
However, each accommodation does not necessarily produce one additional vehicle or one daily trip. Actual traffic depends on occupancy, travel behavior, staffing, shuttle services and other factors.
What Did the South Seas Traffic Review Conclude?
During the rezoning process, county traffic reviewers concluded that the evaluated road segments would continue operating at an acceptable level of service under the assumptions used.
Sanibel officials and other opponents raised concerns about broader impacts on the transportation network, including roads beyond the immediate resort property.
These different perspectives highlight why study boundaries and modeling assumptions matter.
An intersection or roadway segment may meet a technical level-of-service standard while travelers still experience substantial delays elsewhere in the network.
Should Future Captiva Development Be Included in Roundabout Planning?
A comprehensive traffic evaluation should explain whether it includes the additional trips associated with approved development at South Seas and other foreseeable changes in tourism, housing and commercial activity.
It should also distinguish between existing conditions, approved development and speculative future growth.
If Sanibel is considering a permanent intersection redesign, residents deserve to understand whether the projected benefits remain meaningful under realistic future traffic conditions.
Thinking Outside the Roundabout: What Other Solutions Have Been Considered?
A roundabout is not the only potential approach to managing Sanibel traffic.
Some alternatives focus on increasing physical roadway capacity. Others focus on reducing the number of vehicles traveling at the same time.
Could the Causeway Have Three Lanes During Peak Traffic?
One frequently discussed idea is using two outbound lanes and one inbound lane during heavy departure periods.
The city's 2025 feasibility review found that simply restriping the existing bridges would raise significant safety concerns involving available roadway width, shoulders and emergency access.
Substantial bridge modifications or widening would be a much more expensive undertaking.
Consequently, a reversible-lane arrangement should not be presented as a simple or immediately available solution.
Would Restricting Bicycles on the Causeway Help?
Some residents have questioned whether limiting bicycle traffic during the busiest commuting periods could improve vehicle movement.
However, restricting bicycles would not solve the underlying bridge-width limitations identified in the engineering review.
It would also raise questions about transportation access, safety, legal authority and the needs of people who use bicycles for commuting.
Any proposal involving bicycles would require a separate safety and accessibility analysis.
Could Changing Work Schedules Help?
Staggering employee arrival and departure times could potentially reduce the concentration of vehicles during certain peak periods.
This approach has been discussed in earlier Sanibel traffic-management efforts.
Its effectiveness would depend on employer participation, staffing requirements and how much commuting demand could realistically shift.
What About Shuttles, Carpooling and Better Traffic Information?
Other possibilities include expanded employee transportation programs, shared rides, real-time traffic information, better coordination of visitor arrival and departure times, and improved traveler communication.
Some measures could be implemented seasonally or tested before major construction.
Others would require ongoing funding, cooperation among employers or coordination with Lee County.
Could Temporary Traffic Management Be Tested?
Traffic control adjustments during the busiest periods might offer opportunities for evaluation, subject to engineering review and public safety requirements.
The value of a pilot program would be the opportunity to measure results, including total travel times and queue lengths, before making permanent changes.
No single alternative should be assumed to solve the problem without supporting data.
How Does Sanibel's Character Factor Into the Debate?
Sanibel's transportation policies have historically reflected the community's commitment to preserving its barrier-island character.
The absence of conventional traffic signals at major island intersections, the extensive shared-use path system and the emphasis on environmental protection contribute to Sanibel's distinctive atmosphere.
For some residents, a roundabout represents a practical way to improve traffic movement without installing a traffic signal.
Others are concerned about the size, appearance, construction impacts and potential changes to pedestrian and bicycle travel.
These are legitimate planning considerations that extend beyond vehicle delay calculations.
The final evaluation should consider safety, accessibility, landscaping, environmental impacts, emergency response and the island's long-term community vision.
What Could the Roundabout Mean for Sanibel Real Estate?
Transportation access is one of many factors influencing how people experience a community.
For buyers considering Sanibel or Captiva, seasonal traffic can affect commuting, access to mainland healthcare, shopping, airport travel and everyday convenience.
However, the same seasonal activity supports businesses, recreation and the social atmosphere that many winter residents enjoy.
For Buyers
Prospective buyers should experience Sanibel during different times of year whenever possible.
A property that feels conveniently located in September may offer a different driving experience during February or March.
Buyers who regularly travel to the mainland may want to evaluate commuting patterns, while those who spend most of their time on the island may place greater value on proximity to beaches, restaurants, shopping and shared-use paths.
For Sellers
Sellers can help prospective buyers understand the practical advantages of their property's location.
Convenient access to everyday services, walkable destinations, bicycle paths and recreational amenities may be meaningful selling points.
However, it would be premature to claim that the proposed roundabout will increase or decrease property values.
No such outcome has been established, and real estate values are influenced by many factors beyond transportation design.
For Vacation Rental Owners
Seasonal accessibility, visitor experience and travel convenience are relevant considerations for vacation properties.
However, rental performance also depends on location, property condition, amenities, regulations, operating costs and market demand.
A roundabout's potential effect on vacation rental demand cannot be reliably determined without further evidence.
Questions Sanibel Residents Should Ask Before a Final Decision
The most useful public discussion may be less about whether roundabouts are generally effective and more about whether this particular design addresses Sanibel's specific transportation conditions.
Before a final construction decision, residents may want clear answers to the following questions:
How much would the proposed roundabout reduce total travel time from western Sanibel and Captiva to the mainland during peak season?
What happens when outbound Causeway traffic is already at capacity?
Could queues extend into the roundabout or prevent vehicles from entering from certain approaches?
Does the latest analysis address the Causeway merge configuration identified in earlier studies?
Are the traffic projections based on realistic winter-season conditions?
Do the models include approved South Seas development and other foreseeable growth?
How would pedestrians and cyclists safely navigate the redesigned intersection?
What are the estimated construction costs, ongoing maintenance costs and anticipated construction disruptions?
What would happen to traffic during construction?
How do the projected benefits compare with less expensive seasonal traffic-management alternatives?
The answers should help residents distinguish improvements at the intersection from improvements to the overall island transportation system.
Frequently Asked Questions About the Sanibel Roundabout
Where would the Sanibel roundabout be located?
The proposed roundabout would replace the existing four-way stop at Periwinkle Way, Causeway Boulevard and Lindgren Boulevard, near the island's primary entrance from the Sanibel Causeway.
Has construction of the roundabout been approved?
An advisory referendum has been called to obtain voter input. The referendum does not itself authorize construction or approve construction funding.
Will a roundabout eliminate Sanibel's seasonal traffic congestion?
Not necessarily. A roundabout may improve intersection operations, but congestion may continue if the connecting roads or Causeway remain at capacity.
How many people are on Sanibel during peak season?
Sanibel's estimated resident population was 6,303 in 2025. Historical estimates suggest that tens of thousands of residents, seasonal visitors, workers and day visitors may be present or using the island on busy winter days. A historical Chamber estimate placed the combined Sanibel and Captiva peak-season population at up to 40,000, but that is not a verified current count.
Why is traffic worse in winter?
Winter brings more seasonal homeowners, vacation renters, hotel guests and day visitors. Their travel overlaps with daily commuting, deliveries and year-round residential traffic.
How much more traffic does Sanibel experience in high season?
Official records show approximately 296,471 inbound Causeway vehicle crossings in March 2025 compared with 215,005 in August 2025, a difference of nearly 38%. These are monthly crossings, not unique vehicles or people.
Would adding a third Causeway lane solve the problem?
The city's 2025 feasibility review identified significant safety and engineering obstacles to simply converting the existing bridge configuration into three travel lanes. More extensive modifications would require additional investment and evaluation.
Could South Seas redevelopment increase Sanibel traffic?
Potentially. Additional accommodations and resort activity on Captiva could generate more guest, employee and service trips through Sanibel. The amount would depend on actual development, occupancy and travel patterns.
How much has Sanibel authorized for recent traffic studies?
Recent City Council records identify $193,665 for the 2024 intersection study and 2025 Causeway three-lane feasibility study. Including a separate speed limit study brings the total for those three authorized projects to $217,991. These are approved amounts, not a verified total of payments made.
Where can I see current Sanibel traffic conditions?
Live camera feeds and available traffic information can help residents and visitors assess travel conditions before leaving.
See our Sanibel Live Traffic Cameras resource for additional information.
The Bigger Question: What Kind of Transportation Future Does Sanibel Want?
Sanibel's roundabout discussion is ultimately about more than replacing stop signs with a circular intersection.
It involves balancing the transportation needs of year-round residents, seasonal homeowners, vacationers, employees, businesses, cyclists and pedestrians.
It also requires planning for an island whose population and traffic demands change dramatically throughout the year, while access to the mainland remains limited.
Historical studies have identified recurring challenges involving intersection operations, Causeway capacity and peak-season congestion.
More recent studies have added information about potential improvements, engineering constraints and public costs.
The question now is how those findings should guide the next decision.
A successful transportation strategy should be evaluated not simply by how efficiently vehicles pass through one intersection, but by whether it improves safety, travel reliability and the overall experience of living, working and visiting Sanibel.
For those considering buying or selling property on Sanibel or Captiva, understanding the island's transportation challenges is part of understanding its distinctive lifestyle.
Explore Sanibel and Captiva real estate or speak with the local team at Pfeifer Realty Group about how location, seasonal access and community amenities fit your real estate goals.
Sources and Further Reading
City of Sanibel, Resolution 26-026a, Roundabout Advisory Referendum, September 14, 2026.
City of Sanibel, Periwinkle Way/Causeway Boulevard Intersection Study, Kimley-Horn and Associates, 2024–2025.
City of Sanibel, City Council Meeting Records, May 7, 2024, Resolution 24-026, Intersection Study Appropriation.
City of Sanibel, City Council Meeting Records, June 3, 2025, Causeway Three-Lane Feasibility Study and Speed Limit Study.
City of Sanibel, City Council Meeting Records, March 3, 2026, Intersection Engineering and Design Discussions.
Lee County Metropolitan Planning Organization, Roundabout Feasibility Study, 2017.
University of South Florida Center for Urban Transportation Research, Regional Bridge and Toll Traffic Research, 1997.
U.S. Census Bureau, QuickFacts, Sanibel City, Florida, July 2025 Population Estimate.
City of Sanibel, Long-Term Recovery Plan, 2024.
City of Sanibel and Lee County Department of Transportation, Sanibel Causeway Vehicle Counts, 2025.
Sanibel-Captiva Chamber of Commerce, Historical Seasonal Population Information.
Islander Magazine, Historical Sanibel Island Population and Visitor Profile.
Lee County Board of County Commissioners, South Seas Resort Rezoning Proceedings, August 2025.
Gulfshore Business, South Seas Resort Rezoning Coverage, August 7, 2025.
Sanibel-Captiva Chamber of Commerce, Seasonal Traffic Management Information, 2015.
Editorial note: Historical population estimates, traffic projections, study appropriations and proposed development figures are identified by their reporting periods. Actual conditions, expenditures and project approvals may change. This article is intended to inform readers about the transportation debate and does not endorse a particular referendum outcome.