Cycling for Everyone
Cycling for Everyone

TNL assists California Highway Patrol with the automatic identification of noisy vehicles

15 August 2023

The California Vehicle Code requires the motor sounds of vehicles to be below specified loudness levels. With a recent bill, the California State Senate calls for the evaluation of sound-activated enforcement devices (SAEDs) to identify vehicles that are too loud automatically. TNL is developing a SAED with a cloud-connected software back end for evaluation by the California Highway Patrol.


Research shows traffic noise may lead to adverse health effects, such as headaches, sleep disturbance, stress, high blood pressure, and an increased risk of heart disease and hormonal imbalances. Therefore, for public health’s sake, California maintains strict limits on vehicle engine noise. The California State Senate has ordered the selection and evaluation of sound-activated enforcement devices in 27150.4 of the Vehicle Code for enforcement purposes.

CHP testing SAEDs for California State Senate

The SAEDs will enable the identification and prosecution of violations of vehicle noise limits. The devices will detect and record excessive vehicle noise when it happens, locate the vehicle that causes the noise, and take a video of the vehicle for identification. The California Highway Patrol will install, utilize and evaluate SAEDs at multiple locations to test the effectiveness, reliability, and precision of the devices. After successful completion of the tests, which run last for a period of one year, judicial aspects such as chain of evidence and privacy issues shall be evaluated.

TNL assembling SAEDs and developing software back end

TNL will assemble the testable SAED, which consists of two Sorama sound sensors, two Axis cameras, a Class 1 acoustic analyzer, and a 4G cellular connection kit. Additionally, TNL will develop a cloud-based back end and a web-based dashboard for the CHP to use and evaluate. The SAEDs will be installed at a location near Sacramento in order to test their usability and reliability, depending on different circumstances. TNL will train system users and provide technical support during the evaluation period.

About TNL

TNL is supporting government agencies to dramatically increase the mobility service levels provided to US citizens, visitors, and businesses. We are very excited to have been selected by CHP to support them in this important project. TNL is a 37-year young international firm and the market leader in mobility solutions in Europe. Like Amsterdam and Rotterdam in The Netherlands, Oslo in Norway, and Copenhagen in Denmark, our USA clients like San Francisco and Portland are the leading cities in multi-modal traffic flow and public transit service levels. We are proud to be instrumental in establishing and delivering those world-renowned transit and mobility services to the citizens and businesses in the USA.



Photo: Gabriel Bouys / GETTY IMAGES

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