New research shows that by slowing cars at intersections, bike lanes increase safety for all road users.

Motor vehicle crashes are a leading cause of death in the U.S. among individuals under 55 (CDC, 2021). Non-motorists, including pedestrians, cyclists, and e-scooter users, are at a higher risk of fatality compared to drivers and passengers in motor vehicles. Active travel has recognized public health, economic, and environmental benefits. Providing bicycle facilities, such as bike lanes, can reduce the likelihood and severity of crashes involving cyclists while promoting active transportation. Research indicates that bicycle lanes can decrease crashes on urban local roads by 30% to 49% (FHWA, 2022).

The National Highway Traffic Safety Administration (NHTSA) documented that fatal crashes involving bicyclists in 2020 were at their highest level since 1987 in the United States, with 938 cyclists killed, reflecting a 9.2% increase from 2019 (NHTSA, 2022). Many crashes occur at intersections, which present a higher potential for conflicts; the Federal Highway Administration (FHWA) estimates that over 50% of all fatal and injury crashes happen at or near intersections (FHWA, 2021).

Temporary bike lanes, referred to as “pop-up” bike lanes, are low-cost and flexible interventions intended to create a safe space for cyclists and other micromobility users. Urban planners are increasingly using these lanes to assess the potential for more permanent bicycle lanes. The implementation of pop-up bike lanes gained momentum in the early months of the COVID-19 pandemic, facilitating safe outdoor travel and exercise while adhering to social distancing guidelines (UCI, 2020).

Studies indicated that pop-up bike lanes were associated with a rapid increase in cycling within the first four months of the pandemic (Kraus & Koch, 2021). Common bike lane configurations include painted lanes (striped or fully painted), delineator-protected lanes (using traffic cones and bollards), and buffered lanes with protective infrastructure. This study focuses on the comparison of a delineator-protected bike lane and a painted-only bike lane, with the former referred to as delineated bike lanes. In April 2022, a temporary bike lane was implemented near a signalized intersection in Asbury Park, New Jersey (Fig. 1).

The bike lane was delineated with orange cones, traffic delineators (bollards), and temporary chalk paint on Cookman Avenue and at the intersection, while Asbury Avenue featured only paint due to road width restrictions. Both streets have a posted speed limit of 25 mph (40 kph). The primary focus of this study is on traffic flowing to and from Cookman Avenue, where substantial changes in road configuration occurred (see Fig. 2).

Three different road configurations were examined for the intersection and on Cookman Avenue: no bike lane, a painted-only bike lane, and a painted bike lane with traffic delineators (Fig. 3).

Fig. 3. Painted-only bike lane (top) and traffic bike lane with traffic delineators (bottom) on Cookman Avenue. Pictures taken by the research team.

Delineated bike lanes utilize plastic delineators and a buffer space to provide physical separation from motorized traffic (City of Minneapolis, 2021). To create the bike lane, nine parking spots were removed; during the pilot phase (off-season with limited tourist traffic), parking availability was adequate. Each traffic lane was narrowed by at least one foot to establish a three-foot buffer between the bike lane and motorized traffic. The configurations on Cookman Avenue, visualized in Streetmix (Streetmix, 2022), are presented in Fig. 2.

The relationship between bike lanes and cyclist safety is well established in existing literature. However, the potential secondary benefits of bike lanes for pedestrian and motor vehicle safety have not been thoroughly investigated. This study examines the impact of a pop-up bike lane on motor vehicle speeds at an intersection, focusing on two primary questions:

1. Does the presence of a delineated bike lane, marked with traffic cones and plastic delineators, reduce motor vehicle speeds at an intersection? and
2. Is the presence of a painted bike lane associated with decreased motor vehicle speeds at the same intersection?

The hypothesis posits that bike lanes with traffic delineators will exert a more significant traffic-calming effect, resulting in greater reductions in speed compared to painted-only bike lanes. Data on the speeds and trajectories of 9,575 vehicles were analyzed using computer vision techniques. Each vehicle’s speed and direction were detected and classified through computer vision algorithms, facilitating efficient data analysis.

Generalized linear modeling (GLM) was employed to estimate the effect of the bike lane on vehicle speeds. After controlling for factors such as free-flowing vehicles, turning direction, time of day, and day of the week, the analysis revealed that vehicle speeds, on average, decreased in the presence of a bike lane. In particular, vehicles turning right demonstrated the most significant average speed reduction of 21% when a delineated bike lane was present, while controlling for other variables.

Click here to read the full study.