Introduction
On April 14, 2022, two speed cameras were installed on Baltimore’s I-83 expressway at the Northbound and Southbound locations where it intersects West 41st Street. The area of I-83 had been a major source of speeding and was even deemed the “Grand Prix” based on the way people would drive its winding curves.
Trial Period Shows Promise
For 90 days following installation, the City of Baltimore conducted a warning period where speed cameras only issued warnings to motorists exceeding the speed limit by 12 miles per hour or more. Early anecdotal evidence showed that crashes were down after speed camera installation. To determine whether the I-83 speed cameras truly worked and see how driver behavior had changed, the City of Baltimore decided to conduct a speed study.
AirSage Data Selected For Speed Study
To complete the corridor speed study, the City of Baltimore needed highly accurate connected vehicle (CV) data. AirSage was uniquely positioned with its Trajectory Data and Safety Events Data products to provide comprehensive CV data details like timestamp, instantaneous vehicle speed observations, and events data (harsh braking, harsh cornering, and harsh acceleration) that were crucial for the project. AirSage data proved ideal, offering individual vehicle speed observations unlike traditional speed data sources that provide only aggregated segment-level averages. Additionally, it enabled pre- and post-implementation analysis using historical data, a capability not possible with manual data collection.
Data Acquisition and Delivery
Once the City of Baltimore selected AirSage, they collaborated with the team to customize the dataset to their specific needs, adding supplementary fields for Distance and Time from key road features, such as "enforcement ahead" signs and enforcement cameras. Overall, the AirSage deliverable included continuous Trajectory Data from January 1, 2022 to May 20, 2023 and continuous Safety Events Data from January 1, 2022 to August 31, 2023.
Results
After securing the necessary data, the City of Baltimore enlisted their on-call consultant, Mead & Hunt, to conduct the speed data analysis. With AirSage having already completed the heavy data processing, Mead & Hunt could fully dedicate their time to integrating crash and other datasets, interpreting the results, and providing recommendations for the City.
At the conclusion of the six-month analysis, Mead & Hunt’s findings revealed:
Speed point density with regard to camera/sign (February - March)
Speed with regard to cameras/signs (February - March)
Speed change in time and distance
Conclusion
Ultimately, Mead & Hunt found that the I-83 speed cameras effectively slowed down traffic following implementation. Further confirmation indicated that the observed speed reductions aligned with crash patterns provided by the City of Baltimore, suggesting a direct correlation between speed enforcement and safety outcomes. However, the findings also revealed that the effect on driver behavior did not persist throughout the entire corridor. Instead, speed decreases were primarily isolated to the areas near the cameras, with an increase in speeds observed in the northbound direction as drivers exited the city limits. This evidence underscores the need for potential policy adjustments or additional measures, such as increased enforcement or educational campaigns, to sustain the impact of speed reduction throughout the corridor and enhance overall traffic safety.
To learn more about AirSage Trajectory Data or Safety Events Data, visit www.airsage.com
Sources:
https://www.cbsnews.com/baltimore/news/speed-cameras-on-i-83-in-baltimore-to-launch-april-14
