In addition to aerodynamics and the interaction between the vehicle and the pavement, highway traffic noise can be caused by the vehicle itself and the type of tires.1 Therefore, low-noise vehicles and tires are potential approaches to combat noise pollution, particularly in urban environments.
Regarding vehicle type, vehicles with an internal combustion engine (ICE) emit noise through engine vibrations and from the exhaust system.2 Vehicles with larger engines, such as heavy trucks, or higher speeds may emit higher levels of noise. However, electric vehicles (EVs) produce very small levels of noise, particularly at lower speeds. At higher speeds, the noise level between EVs and regular vehicles may be roughly the same due to tire noise.
Tire noise is associated with tread pattern, the number of tires, tire width, rubber elasticity, and other factors.1,3 For example, tires with varied tread block sizes, less space between tread blocks, and semi-closed shoulders can help dampen noise.4 Additionally, some research has pointed to low rolling resistance tires as a solution to minimize road traffic noise.5
How it Helps
Potential Risk to Pedestrians:
One of the ongoing concerns regarding low-noise vehicles, particularly EVs and hybrid vehicles, is the potential risk to pedestrians when they are crossing the street or near roadways.8 The low levels of noise emitted by these vehicles could pose a safety risk to vulnerable road users, especially children and older adults. Therefore, federal agencies and car manufacturers are trying to figure out a solution to this problem, such as requiring vehicles to emit a warning sound that would allow pedestrians to detect the vehicle.2
Education & Incentives:
To encourage more people to purchase EVs and other low-noise vehicles and low-noise tires, some form of education or incentive program will be needed to share information about the negative health impacts associated with traffic noise. Car manufacturers may also need an incentive to urge them to come up with solutions to reduce highway traffic noise through vehicle modifications.
1) National Highway Traffic Safety Administration’s (NHTSA) Minimum Sound Requirements for Hybrid and Electric Vehicles
In 2016, NHTSA added a sound requirement for all newly produced hybrid and electric vehicles to help protect pedestrians, particularly the visionally impaired, by enabling them to detect the location of these vehicles. This requirement will hopefully reduce the incidence of car-pedestrian crashes.