Enhancing Intersection Efficiency: A Comparative Analysis of Converting Single-Lane Roundabout to Turbo Roundabout

Area of Science:

• Civil Engineering
• Transportation Engineering
• Traffic Safety

Background:

• Single-lane roundabouts (SLR) are common but can experience operational challenges.
• Turbo roundabouts (TR) are an alternative design aiming to improve traffic flow and safety.
• Evaluating the comparative performance of SLR and TR designs is crucial for traffic management.

Purpose of the Study:

• To compare the operational and safety performance of a conventional single-lane roundabout (SLR) and a turbo roundabout (TR).
• To assess the effectiveness of a TR conversion in improving traffic conditions at a specific intersection.
• To analyze the impact of traffic volumes and patterns on the performance of both roundabout types.

Main Methods:

• A mixed-methods approach combining field traffic data collection and microsimulation modeling.
• Capacity calculations based on national guidelines (TP 100 and TP 102).
• Development and validation of a calibrated microsimulation model to compare SLR and TR designs under peak-hour conditions.

Main Results:

• The turbo roundabout (TR) design demonstrated reduced average delays and queue lengths compared to the single-lane roundabout (SLR).
• The TR design effectively eliminated internal weaving conflicts observed in the SLR.
• Performance benefits of TR are conditional, influenced by traffic volumes, turning-movement patterns, and pedestrian/cyclist interactions.

Conclusions:

• Turbo roundabouts (TR) offer potential operational improvements over single-lane roundabouts (SLR) under specific traffic conditions.
• The effectiveness of TR designs is contingent upon traffic characteristics and the integration of vulnerable road users.
• Further research is needed to understand the full applicability and limitations of TRs in diverse traffic environments.