Evaluating Safety Impacts of Protected Intersection in Tampa Bay

Abstract: A protected intersection, also known as a Dutch-style junction, setback, or offset intersection, is a type of road intersection designed to separate bicycles from vehicle traffic physically. The primary goal of the protected intersection is to enhance safety and comfort for pedestrians and bicyclists while maintaining efficiency for motor vehicles. The National Association of City Transportation Officials (NACTO) design guide states, "This design can reduce the likelihood of highspeed vehicle turns, improve sightlines, and dramatically reduce the distance and time during which people on bikes are exposed to conflicts." The critical elements of protected intersections include Bike Box - a designated space where bicyclists can wait safely before entering or crossing the intersection, Bike Line Setback—a design feature that moves the bike crossing further away from the vehicle stop line, creating additional space between motor vehicles and bicyclists, and Corner Island - a raised and tight corner forces drivers to reduce their turning speed to increase the safety of pedestrians and bicyclists.

West Cleveland Street, a one-way, two-lane street in the heart of the City of Tampa's downtown area with a speed limit between 25-35 mph, has been recognized as one of the most dangerous streets in Tampa for drivers and pedestrians. Between 2021 and May 2024, there have been 80 crashes on this stretch of roadway, 40% of which resulted in injuries. As part of the City of Tampa's Vision Zero efforts, the city reconstructed a portion of W Cleveland St, including installing a projected intersection (W Cleveland St. @ W Hyde Park Ave.) to provide drivers, pedestrians, and bicyclists a safer environment.

A before-after study compared safety-related behaviors between the original and protected intersection designs at W Cleveland St and S. Hyde Park Ave to determine the protected intersection's safety effects on bicyclists, pedestrians, and other vulnerable road users. The research team used AI-powered computer vision tools to collect safety-related behaviors, including bicycle/e-scooter travel and cross routes, vehicle right-turn routes, and vehicle yielding to pedestrian/bicycle/e-scooter rate, for two days (Thursday and Saturday) before and after the implementation.

The study results indicate that the designated crossbikes at the protected intersection reduce bicyclist and e-scooter riders' unsafe crossing behaviors (crossing in non-protected areas); the designed bike lanes increase riders' compliance and reduce bike lane violation rates on riding in the opposite direction of traffic; and the bike box and tight turn corner design at the protected intersection increase the yielding rate of right-turn vehicles. However, the study also found that some drivers and non-motorists do not fully understand the protected intersection intention and regulations. Based on the results, education program campaigns and engineering countermeasures are suggested to address the potential issues and enhance the performance of the protected intersection in protecting non-motorists.