South Liberty Parkway
GBA partnered with the City of Liberty, Missouri, to evaluate and plan future intersection improvements along South Liberty Parkway, a critical east–west corridor connecting Interstate 35 and Missouri Route 291. Extending from Withers Road to MO-291, this largely undeveloped corridor represents a significant opportunity for future residential growth, making proactive infrastructure planning essential.
Building on previous studies and the city’s comprehensive planning efforts, GBA developed a forward-looking framework to guide the implementation of modern roundabouts as traffic volumes and surrounding development increase. The study provides Liberty with a clear, data-driven roadmap to ensure the corridor evolves safely and efficiently alongside the community.
Planning for Growth with Modern Solutions
Rather than defaulting to traditional signalized intersections, the study evaluated the use of six strategically placed modern roundabouts along the corridor. These locations were selected to balance safety, operational performance and long-term development needs.
Modern roundabouts offer measurable advantages in both safety and efficiency. Their geometry reduces conflict points and lowers vehicle speeds, significantly decreasing the likelihood and severity of crashes. At the same time, yield-controlled entries promote continuous traffic flow, reducing congestion, delay and idle time for motorists.
Beyond operational benefits, the proposed roundabouts support sustainability goals by lowering fuel consumption and vehicle emissions while eliminating the ongoing maintenance and energy costs associated with signalized intersections.
A Data-Driven and Adaptable Approach
The study required careful consideration of several complex variables, including projected traffic demand, land use planning and long-term growth scenarios. GBA applied advanced modeling and performance analysis to evaluate how the corridor will function over time, accounting for uncertainty in development timelines.
To support informed decision-making, the team incorporated life-cycle cost analysis, demonstrating that while roundabouts may require higher initial investment, they provide long-term economic value through reduced crash costs, lower maintenance needs and improved operational efficiency.
Importantly, the study establishes traffic volume thresholds that signal when intersection improvements or additional roundabouts should be implemented, giving the city a flexible and scalable framework for future action.
 |
 |
Supporting Community and Connectivity
In addition to improving traffic operations, the proposed roundabouts enhance safety and accessibility for all users. Features such as shorter pedestrian crossings, refuge islands and reduced vehicle speeds contribute to a more comfortable and inclusive transportation environment for drivers, pedestrians and cyclists alike.
The design also creates opportunities for placemaking through landscaped central islands, allowing each roundabout to serve as a visual gateway that reinforces community identity along the corridor.
Aligned with Liberty’s 2023 Comprehensive Plan, the study reflects a broader commitment to smart, sustainable infrastructure that supports long-term growth while maintaining quality of life for residents.
Delivering Lasting Value
GBA delivered a comprehensive report that equips the City of Liberty with a practical, implementation-ready guide for corridor improvements. By combining technical analysis with forward-thinking planning, the South Liberty Parkway Roundabout Study positions the city to proactively address growth while enhancing safety, mobility and sustainability.
As these roundabouts are implemented over time, they will serve as visible examples of how thoughtful engineering can shape safer, more efficient and more connected communities.