Before-After Study in Sweden Found Spot Speed Cameras Reduced Fatalities by 38.6 Percent
Researchers Assessed the Effect of Spot Speed Cameras Based on 361 Speed Measurement Spots and 202 Road Segments in Sweden
Sweden
Spot speed cameras in a series - Effects on speed and traffic safety
Summary Information
Speed cameras are used by transportation and traffic agencies owing to their effectiveness in improving speed compliance and safety by reducing the number of fatalities and serious injuries related to speeding behavior. This study investigated the effects of speed camera systems in Sweden on mean speeds, speed compliance, and on the number of fatalities and serious injuries. The speed cameras in this study measure vehicle speed using radar and take pictures only when a driver exceeds the speed limit. This study used 20 years of data (from 2002 to 2021) to conduct a before-after analysis of 361 speed measurement spots. Empirical Bayes before-after analysis with control was applied to crash outcomes on 202 road sections.
METHODOLOGY
The effects of speed cameras were studied near individual cameras, between cameras, and across entire road sections. Camera locations were defined as within 250 meters (820 feet) before or after the camera, and between cameras as more than 250 meters but within 10 kilometers (6.2 miles). Speed data was obtained from Sweden's National Speed Measurements database for April–September, 2002–2017, focusing on locations measured both before and after camera installation. Additional data was collected from roads with new speed cameras installed during 2019–2021, measuring speeds one month before and one year after installation. The dataset includes individual vehicle speeds, allowing for analysis of mean speeds and compliance. Crash data (2003–2018) from Sweden's national database was used to assess the impact of speed cameras on fatalities and serious injuries.
FINDINGS
- This study found that mean speed decreased by 3.5 km/h (2.17 miles per hour) for all vehicles and all road sections analyzed.
- The results also showed a mean speed decrease of 7.9 km/h (4.9 miles per hour) at cameras and 3.0 km/h (1.86 miles per hour) between cameras.
- Results also indicated that spot speed cameras in a series reduced fatalities by 38.6 percent.
- This study also found that speed compliance increased by 16 percent points, 42 percent points at cameras and 13 percent points between cameras.
