**3.1 Electric vehicles**

Electric vehicles (shown in **Figure 13**) present the future in terms of reducing noise pollution in urban areas. Electric vehicles are quieter especially when compared to vehicles with an internal combustion engine.

Electric vehicles at low speeds produce very low levels of noise, i.e., in current urban environments, these vehicles are practically silent and unnoticeable. For example, the difference in noise level between an electric vehicle and an internal combustion engine vehicle can be greater than 6 dBA at 10 km/h [6]. At higher speeds, both types of vehicles become equally loud, mainly due to the tire noise. In urban areas, for pedestrians (especially for vulnerable groups: children and visually impaired people), it becomes much more difficult to detect electric vehicles due to their aforementioned lower noise levels [6]. Therefore, it is necessary to find a solution in the form of an audible signal that electric vehicles will emit in different driving modes.

Since 2009, the Japanese government, the United States Congress, and the European Commission have been studying the legislation to determine the minimum level of emitted sound signal for plug-in electric and hybrid vehicles when operating in electric mode. This level of audible signal must be such that visually impaired people, other pedestrians, and cyclists can hear the electric vehicles in motion and detect from which direction they are coming from. Several tests and studies have shown that vehicles operating in electric mode below 32 km/h are almost inaudible for pedestrians [7].

In 2011, the European Commission composed guidelines for Acoustic Vehicle Alerting Systems (AVAS). The aim of the guidelines was to present

**87**

*Traffic Noise*

*DOI: http://dx.doi.org/10.5772/intechopen.92892*

final approval of the April 2014 proposal [10].

more the noise levels in urban environments?"

**3.2 Smart traffic management**

multiple benefits such as:

recommendations to manufacturers for a system to be installed in this type of vehicles that would emit an audible signal to pedestrians and other vulnerable groups in traffic. The guidelines recommend that AVAS automatically generate a continuous sound in the minimum range of vehicle speeds from standing at a place (0 km/h) and starting to drive (up to approximately 20 km/h) and when driving backwards, if applicable to that category of vehicle. Furthermore, the guidelines suggest which types of sounds are not suitable for this purpose [8]. In February 2013, the European Parliament decided that the law draft should combine series of tests, norms, and measures that first must be developed in order to make AVAS mandatory in the future. The approved amendment stipulates that "the sound generated by the AVAS should be a continuous sound of the vehicle in operation providing information to pedestrians and vulnerable traffic users. The sound should clearly demonstrate the behavior of the vehicle and should sound similar to the sound of a vehicle of the same category equipped with an internal combustion engine" [9]. In April 2014, a law (Regulation (EU) No 540/2014) was approved by the European Parliament requiring AVAS to be mandatory for all new electric and hybrid vehicles. The new guidance proposes a transitional period of 5 years after the announcement of the

For example, a case study was carried out in Zagreb in 2019 [11], which involved 201 participants who had the task to fulfill a specially designed questionnaire. This case study addresses the issue of electric cars in everyday traffic. The research was focused on assigning a desirable (both for pedestrians and drivers) and, at the same time, detectable warning sound to an electrical vehicle in the daily traffic. The case study showed that the majority of participants (especially the ones with a driving license) would prefer that their electric vehicle sounds like an internal combustion engine car. The "nondrivers" were more open to the solution that an electric vehicle has a different sound than a "regular" car. According to the study, they were more opened to a solution of adding a sound of an electric motor to the electric vehicle as a warning sound which would distinguish the electric cars from cars with internal combustion engine in everyday traffic. However, an important question concerning the overall quality of life remains: "Which one of these two sounds would increase

Finally, it can be concluded that electric vehicles will play a significant role in reducing noise levels especially in urban areas while adequately addressing the problem of emitting a certain warning sound when parking, moving forward, and stopping. It is important to note that the unique warning sound has not yet been implemented, i.e.,

Smart traffic management is a system in which centrally controlled traffic signals and sensors regulate the flow of traffic through the city in compliance with

Upgrading and integrating all the signals on major roads in the city will have

• Significant reduction of daily traffic congestion, equalization of traffic flows,

• Pollution reduction in the city: stop-start driving is inefficient and polluting.

• Providing priority for busses approaching intersections and phase-coordinating

various car manufacturers are still "experimenting" regarding this issue.

and prioritization of traffic in response to real-time demand.

traffic lights enabling a "green wave" through the city.

the current state on the roads in the city (see **Figure 14**).

**Figure 13.** *Electric vehicles: the future.*

#### *Traffic Noise DOI: http://dx.doi.org/10.5772/intechopen.92892*

*Noise and Environment*

**3.1 Electric vehicles**

driving modes.

almost inaudible for pedestrians [7].

In the following sections, a more detailed explanation on how electric vehicles affect the reduction of noise levels will be provided, especially in urban areas. On the other hand, problems which occur with electric cars will be discussed. In addition, the effect of smart traffic management system, traffic behavior changes, and

Electric vehicles (shown in **Figure 13**) present the future in terms of reducing noise pollution in urban areas. Electric vehicles are quieter especially when com-

Electric vehicles at low speeds produce very low levels of noise, i.e., in current urban environments, these vehicles are practically silent and unnoticeable. For example, the difference in noise level between an electric vehicle and an internal combustion engine vehicle can be greater than 6 dBA at 10 km/h [6]. At higher speeds, both types of vehicles become equally loud, mainly due to the tire noise. In urban areas, for pedestrians (especially for vulnerable groups: children and visually impaired people), it becomes much more difficult to detect electric vehicles due to their aforementioned lower noise levels [6]. Therefore, it is necessary to find a solution in the form of an audible signal that electric vehicles will emit in different

Since 2009, the Japanese government, the United States Congress, and the European Commission have been studying the legislation to determine the minimum level of emitted sound signal for plug-in electric and hybrid vehicles when operating in electric mode. This level of audible signal must be such that visually impaired people, other pedestrians, and cyclists can hear the electric vehicles in motion and detect from which direction they are coming from. Several tests and studies have shown that vehicles operating in electric mode below 32 km/h are

In 2011, the European Commission composed guidelines for Acoustic Vehicle Alerting Systems (AVAS). The aim of the guidelines was to present

quiet road surfaces in terms of noise reduction will be examined.

pared to vehicles with an internal combustion engine.

**86**

**Figure 13.**

*Electric vehicles: the future.*

recommendations to manufacturers for a system to be installed in this type of vehicles that would emit an audible signal to pedestrians and other vulnerable groups in traffic. The guidelines recommend that AVAS automatically generate a continuous sound in the minimum range of vehicle speeds from standing at a place (0 km/h) and starting to drive (up to approximately 20 km/h) and when driving backwards, if applicable to that category of vehicle. Furthermore, the guidelines suggest which types of sounds are not suitable for this purpose [8]. In February 2013, the European Parliament decided that the law draft should combine series of tests, norms, and measures that first must be developed in order to make AVAS mandatory in the future. The approved amendment stipulates that "the sound generated by the AVAS should be a continuous sound of the vehicle in operation providing information to pedestrians and vulnerable traffic users. The sound should clearly demonstrate the behavior of the vehicle and should sound similar to the sound of a vehicle of the same category equipped with an internal combustion engine" [9]. In April 2014, a law (Regulation (EU) No 540/2014) was approved by the European Parliament requiring AVAS to be mandatory for all new electric and hybrid vehicles. The new guidance proposes a transitional period of 5 years after the announcement of the final approval of the April 2014 proposal [10].

For example, a case study was carried out in Zagreb in 2019 [11], which involved 201 participants who had the task to fulfill a specially designed questionnaire. This case study addresses the issue of electric cars in everyday traffic. The research was focused on assigning a desirable (both for pedestrians and drivers) and, at the same time, detectable warning sound to an electrical vehicle in the daily traffic. The case study showed that the majority of participants (especially the ones with a driving license) would prefer that their electric vehicle sounds like an internal combustion engine car. The "nondrivers" were more open to the solution that an electric vehicle has a different sound than a "regular" car. According to the study, they were more opened to a solution of adding a sound of an electric motor to the electric vehicle as a warning sound which would distinguish the electric cars from cars with internal combustion engine in everyday traffic. However, an important question concerning the overall quality of life remains: "Which one of these two sounds would increase more the noise levels in urban environments?"

Finally, it can be concluded that electric vehicles will play a significant role in reducing noise levels especially in urban areas while adequately addressing the problem of emitting a certain warning sound when parking, moving forward, and stopping. It is important to note that the unique warning sound has not yet been implemented, i.e., various car manufacturers are still "experimenting" regarding this issue.

## **3.2 Smart traffic management**

Smart traffic management is a system in which centrally controlled traffic signals and sensors regulate the flow of traffic through the city in compliance with the current state on the roads in the city (see **Figure 14**).

Upgrading and integrating all the signals on major roads in the city will have multiple benefits such as:


**Figure 14.** *Smart traffic management system.*


In addition to the multiple benefits listed above, the system would also provide the perfect opportunity to install tracking equipment and collect a much more detailed traffic and travel data. Each set of traffic lights would have communication equipment that can be used to transmit (anonymously) vehicle data, either from automatic number-plate recognition (ANPR) cameras or Bluetooth detectors and closed-circuit television (CCTV) transmission (if suitable). There are three components in smart traffic management: traffic lights, queue detectors (in terms of traffic congestion) embedded in the road, and cameras and a central control system. Queue detectors define the traffic flow control system on all major roads in the city. The system controls the traffic lights to maintain the free flow of traffic within the city. Every 2 seconds, the system uses a real condition model to decide whether one will have the priority of changing the phase of any of the traffic lights. A system software considered as an "asset" can be defined as, for example, obeying the bus timetable, less pollution at a particular location, or fewer vehicles waiting at a highway toll booth.

If inbound traffic flow control is used, the most remote sets of traffic lights on arterial or radial roads serve as a special function and are technically known as "doors" or "control points." They regulate the flow of vehicles entering the city.

One example of software with the purpose of smart traffic management is split cycle and offset optimization technique (SCOOT) which is used in hundreds of European cities for decades. It is used in Cambridge for coordinating traffic signals, where it usually favors busses. In Zurich, Braunschweig, and Potsdam, the system is used to control all traffic in the city [12]. The software is deployed with "knowledge" of the road network and is trained to respond appropriately to a wide range of scenarios (e.g., major traffic "disruptions" such as an accident on the arterial roads). It is important to note that the system also has the option to manually manage and make changes if there is a need for it.
