**Abstract**

Wireless Power Transfer (WPT) technology can transfer electrical energy from a transmitter to a receiver wirelessly. Due to its many advantages, WPT technology is a more adequate and suitable solution for many industrial applications compared to the power transfer by wires. Using WPT technology will reduce the annoyance of wires, improve the power transfer mechanisms. Recently, the WPT gain enormous attention to charging the on-board batteries of the Electric Vehicle (EV). Several well-known car manufacturing companies start efforts to adopt WPT technology and enhance its features. Therefore, WPT can be achieved through the affordable inductive coupling between two coils named a transmitter and a receiver coil. In EV charging applications, transmitter coils are located underneath the road, and receiver coils are installed in the EV. The inductive WPT of resonant type is generally applied to medium-high power transfer applications like EV charging because it achieves better energy efficiency. In this chapter, various WPT technologies are discussed and tested in EV wireless charging applications. Furthermore, extensive information is given to developing an advanced WPT technology that can transfer maximum power by achieving maximum efficiency.

**Keywords:** Wireless Power Transfer (WPT), Electric Vehicle (EV), Energy Efficiency

## **1. Introduction**

A Wireless Power Transfer (WPT) is one of the promising technologies used to transfer electric energy from a transmitter to a receiver wirelessly. WPT is an attractive solution for many industrial applications due to its enormous benefits over wired connections. The advantages include the no hassle of carrying wires, easy charging, and smoot of power transmission even in unfavorable environmental circumstances.

The idea of wireless power transfer (WPT) was first introduced at the end of the 19th century by Nicola Tesla. He manufactured a wireless lighting bulb that was used to receive electrical charge wireless [1]. Tesla used two metal plates that were closely placed to each other. A high-frequency Alternative Current (AC) potentials were passed between these two plates, and the bulb powered ON. However, some of the issues appeared while using WPT technology. One of the main issues is that the minimum power density and low transfer efficiencies affect when the distances increase. As a result, the performance of WPT technology becomes very slow. Therefore, the WPT technology is improved and used "strong coupled" coils when the distance increases more than 2 m while charging wirelessly [2]. The two

important WPT technologies are Inductive Power Transfer (IPT) and Capacitive Power Transfer (CPT). CPT is only applicable to low power applications with very short air gaps between 10–4 and 10–3 m, whereas IPT can be used for large air gaps around several meters, and its output power is much higher than CPT.

**Figure 1** Compares between CPT and IPT, **Figure 1a** shows the power transfer capability versus gap distance with efficiency values. Furthermore the figure indicates both IPT and CPT can achieve ≥90% efficiency at kilowatt power levels in their respective gap ranges. **Figure 1b** plots the transmitter/receiver area versus throughput power with efficiency. The coupler area is the cross-sectional area through which magnetic or electric fields transfer energy. **Figure 1c** plots the output power density (output power divided by the gap volume) versus frequency [3]. WPT technologies can be applied in television, phone chargers, and induction heating, medical devices, pacemakers, radiofrequency identification, sensors, robotics, and deeply used in wireless charging for EV [4–11].

In CPT and IPT power transfers, the respective energy stored in a unitary volume of space is

$$W\_{\varepsilon} = \frac{1}{2} \varepsilon\_0 E^2 \tag{1}$$

$$W\_m = \frac{1}{2}\mu\_0 H^2 \tag{2}$$

can help reduce the battery pack size and in turn make the EVs more proficient. However, all this cannot be knowledgeable by using traditional inductive chargers and WPT charging through large air gaps and least possible human interaction are

*Relationship between Ampere's law, Faraday's law, Maxwell's equations, inductive-coupling WPT, resonance-*

WPT systems are primarily classified as microwave, evanescent wave, magnetic resonance, electrical resonance, or electromagnetic induction methods. Scientists have newly proposed an electromagnetic induction method that is not premised on transformer coupling. It is revealed that the electric power transmission over a range including a magnetic field resonance method is enabled by adopting this method [13]. Ampere's law, Faraday's law, Maxwell's equations, the inductive-coupling WPT, the resonance-coupling WPT, and WPT via radio waves are the major theory that can describe the functionality of WPT technologies. **Figure 2** shows this relation-

When AC or DC electrical energy is transformed to high-frequency electrical energy by using a high-frequency inverter, the wireless feeding device (Tx.) releases electrical energy through a transmission device into space. Then, the

required [12].

**31**

**Figure 2.**

ship between these theories.

**2. Basic theory of WPT system**

*coupling WPT, and WPT via radio waves [13].*

*Wireless Power Charging in Electrical Vehicles DOI: http://dx.doi.org/10.5772/intechopen.96115*

where *E* and *H* are the intensity of the electric and magnetic fields and, *ε*0 and *μ*0 are the permittivity and the permeability of the free space.

Health and safety, and economic impact are the critical points that should be considered in any technology of WPT for charging EVs or in any other applications. WPT technology for charge replacement, EVs can become gorgeous option. WPT charging has the advantage that it can make the charging process automated, suitable and safe for users and large scale introduction of WPT charging infrastructure

#### **Figure 1.**

*Comparison between CPT and IPT technologies [3], (a) gap distance and output power with efficiency value , (b) coupler area and output power with efficiency value, (c) frequency and output power density with efficiency value.*

#### **Figure 2.**

*Relationship between Ampere's law, Faraday's law, Maxwell's equations, inductive-coupling WPT, resonancecoupling WPT, and WPT via radio waves [13].*

can help reduce the battery pack size and in turn make the EVs more proficient. However, all this cannot be knowledgeable by using traditional inductive chargers and WPT charging through large air gaps and least possible human interaction are required [12].

WPT systems are primarily classified as microwave, evanescent wave, magnetic resonance, electrical resonance, or electromagnetic induction methods. Scientists have newly proposed an electromagnetic induction method that is not premised on transformer coupling. It is revealed that the electric power transmission over a range including a magnetic field resonance method is enabled by adopting this method [13].

Ampere's law, Faraday's law, Maxwell's equations, the inductive-coupling WPT, the resonance-coupling WPT, and WPT via radio waves are the major theory that can describe the functionality of WPT technologies. **Figure 2** shows this relationship between these theories.

## **2. Basic theory of WPT system**

When AC or DC electrical energy is transformed to high-frequency electrical energy by using a high-frequency inverter, the wireless feeding device (Tx.) releases electrical energy through a transmission device into space. Then, the

receiving system (Rx.) converts the electrical power into DC in the recipient electrical apparatus. In addition, the efficiency of the electrical power transmission, medical and environmental influence of electromagnetic waves, and improvement the facile high speed charging, safe security, and energy storage density are essential limits should be considered when WPT is designed for EVs.

**Type Coupling mechanism Resonant**

*Wireless Power Charging in Electrical Vehicles DOI: http://dx.doi.org/10.5772/intechopen.96115*

1 Electrostatic induction

2 Coupled-resonant using electrostatic induction

3 Coupled-resonant with self-resonant coupler (E-field dominant)

4 Far-field type

**Table 1.**

**Figure 5.**

**33**

*Block diagram of WPT system.*

Coupled-resonant using magnetic induction

Coupled-resonant with self-resonant coupler (H-field dominant)

(microwave WPT)

**E-field H-field**

Yes No Power factor

impedance Magnetic induction No Yes

Dominant Negligible Discrete

Dominant

Negligible Dominant

Dominant Small, but not negligible

Coupling in far-field. Ratio of E-field to Hfield is 377 Ω

Small, but not negligible

**mechanism**

compensation may be considered as a resonant circuit

reactance device is necessary for resonance

Coupler acts as resonator

Tx and Rx antennas resonate independently

*Coupling mechanism, resonant mechanism, and impedance matching mechanism for various kinds of WPT.*

Tx/Rx antennas are matched to the source/ load independently

**Impedance matching mechanism (feeding mechanism)**

Not active following for load

According to the load impedance or transmission distance, active following by circuit parameter in impedance matching circuit or transmission frequency is necessary to achieve simultaneous conjugate matching

**Schematic**

WPT systems are classified as microwave, evanescent wave, magnetic resonance, electrical resonance, or electromagnetic induction methods. **Figure 3** shows the relation between transmitted power and transmitted length of these methods for WPT systems. Additionally, WPT can be classified to the kind of Type 1,Type 2, Type 3 and Type 4 as shown in **Figure 4**. **Table 1** shows the relationship of Types 1–4 from the viewpoint of coupling mechanism, resonant mechanism,

**Figure 4.** *Relationship of different kinds of WPT scheme.*

*Wireless Power Charging in Electrical Vehicles DOI: http://dx.doi.org/10.5772/intechopen.96115*

#### **Table 1.**

*Coupling mechanism, resonant mechanism, and impedance matching mechanism for various kinds of WPT.*

**Figure 5.** *Block diagram of WPT system.*


**Abstract**

Gallbladder cancer (GBC) is associated with a sinister prognosis, a short survival time, and early metastasis to distant sites. Chronic inflammation of the gallbladder due to gallstone disease and biliary bacteria remain key factors in the pathogenesis of GBC. The association of chronic bacterial infections with the development of GBC has provided a new perspective on the causation of GBC. A strong link between chronic Salmonella infection and enterohepatic strains of Helicobacter species with GBC has been suggested. It is believed that many other enteric bacterial strains, predominantly the Enterobacteriaceae species, are associated with the development of GBC. However, the available literature mainly comprises observational studies and small meta-analyses necessitating the requirement of a higher level of evidence. This chapter discusses the role of the gut microbiome, dysbiosis and its association with carcinogenesis, and the organisms associated with the causation of GBC.

**Keywords:** gallbladder neoplasm, dysbiosis, gut microbiome, brain-gut axis, gastrointestinal microbiome


**Author details**

Beata Zagórska-Marek University of Wrocław, Wrocław, Poland

\*Address all correspondence to<EMAIL_ADDRESS>
© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A. Components of Urban Gardens

**3**

**Chapter 1**

**Abstract**

recycling

**1. Rationale**

in Fruit Crops

*Pramod Kumar and Simran Saini*

Nutrients for Hydroponic Systems

Hydroponic systems for crop production are nowadays essential to maximize

yields. Sometimes, the benefits of hydroponics have been questioned by the researchers as compared to growing of crops in other soilless culture. The growers raised the crops through hydroponics system get yields more compared to conventional practices as hydroponically grown plants dip their roots directly into nutrient-rich solutions. Therefore, the aim of the current chapter is to provide accurate and updated information about their different nutrients and their composition used hydroponically compared to conventional production mode. This chapter will be divided as the following sections: (1) rationale, (2) nutrient solution technique, and (3) work done on fruit crops. With this chapter, we hope to present an updated

information, comparing hydroponic versus conventional technique.

**Keywords:** soilless culture, hydroponics, conventional production, nutrients,

Hydroponics is the emerging sector of horticulture that deals with growing of plants in a soilless nutrient solution. This term refers to the use of nutrient and water solution for growing plants without soil. Since the ancient time, this technique is being used from thousands of years that traced from the hanging gardens of Babylon and the floating gardens of China. With the decline in arable land, there is a need of alternative to meet the demand of increasing population, and in this regard, hydroponics serves as an additional channel for crop production. In this technique, the crop plant growth is influenced by certain substances in the water. The German botanists, Julius Von Sachs and Wilhelm Knop developed the first standard formula for the nutrient solutions in 1860–61 where the nutrient solutions contained macronutrients the especially nitrogen, phosphorus, potassium, sulfur, magnesium, and calcium varied concentration depending upon crop. Since 100 years back, William Frederick Gericke popularized the idea that plants could be grown in a solution of nutrients and water. He contributed toward hydroponic culture by producing an effective nutrient solution. In the early 1930s, he did an experiment on production of agricultural crops through nutrient culture and termed it as aquaculture. The term so used was dropped due to culturing of aquatic organisms as aquaculture. During 1930s refinement work on hydroponics was expanded toward Europe, Japan, and North America worked England, Africa, Britain, France, Italy, Spain, and Sweden. In 1937, W.A. Setchell introduced the term "hydroponics." The hydroponic nutrient solution includes minerals in the raw


*6.3. Application 3*

The third data set (Linhart and Zucchini [17]) represents 31 times of air conditioning system failure of an aeroplane. Some descriptive statistics are: mean = 55.35, variance = 5132.503, skewness = 1.805, and kurtosis = 5.293.

Initially we computed the moment estimators for the MSHN distribution, and obtained the following estimations: *σM* = 38.125 and *qM* = 2.743. We used these estimations as initial values in computing the ML estimators presented in Table 7. For each distribution we report the estimated log-likelihood.

**Table 7.** ML estimations with the corresponding SE for the models fitted.

Table 8 displays the AIC and BIC for each model fitted. Figure 6 presents the histogram of the data fitted with the HN, SHN and MSHN distributions, provided with the ML estimations.

 313.715

 316.583 **311.908**

**314.776**

AIC

BIC

 325.7224

 327.1564

**Figure 6.** Histogram fitted with the HN, SHN and MSHN distributions provided with the ML estimations.


**11. Conclusion**

Peri-implantitis is an inflammatory disease of microbial origin causing bone loss around the implant, which could lead to the loss of the implant. The etiology of peri-implantitis is associated with a complex microbial biofilm and risk factors such as smoking and diabetes. Occlusal overloading, osteoporosis, and other factors compromising the surgical site might adversely affect the severity of the destruction of the peri-implant tissue. Several surgical and non-surgical therapeutic approaches have been proposed to manage this complex-multifactorial condition. Anti-infective and regenerative therapeutic strategies were used to restore the peri-implant health as well as to achieve new bone-to-implant contact.


*3.2. Timetable Variables*

In this cost model, we have assumed that the route and timetable are identical in both directions. A simple way of describing the timetable is shown in Figure 2. It shows a generic timetable description as a curve showing the number of departures per hour from the end stops and its variation during the day. In the diagram we can see that the timetable can be described by seven time-dependent variables and three variables for number of departures per hour. By changing these 10 variable values, the timetable can be altered in our TCO analysis. Since the buses often run into the night, beyond midnight, the calculation uses time values beyond 24 h, as this simplifies the calculations. In Figure 2, the last bus departs from the end stop at 01:00 in the night, and this is coded as 25.0 h in our model.

**Figure 2.** The generic way of describing the timetable which is used in the TCO model.

In addition to the variables in Figure 2, there are also variables to define the layover time needed off-peak (*T*LayoverOffPeak), during peak times (*T*LayoverPeak), and in the evening (*T*LayoverEvening). The layover time is the time between when the bus arrives at the end stop from one trip, and the time it departs for the return trip. The layover time is mainly used as a buffer time so that a delayed incoming bus shall still mostly be able to depart on time on its next trip. The layover time can also provide some breaks for the driver between trips.

Instead of defining different timetables for the different types of days (weekdays, weekends, holidays etc.) the total traffic during a whole year is instead calculated as the defined typical day, multiplied with the number of effective traffic days which give an estimate of the total yearly traffic. In this paper we use *N*TrafficDays = 313.


**Preface to "Nonequilibrium Phenomena in Strongly Correlated Systems"**

Dmitrii Nikolaevich Zubarev was born in November 27, 1917, in Moscow, Russia. On the occasion of his 100th birthday, a honorary colloquium was performed at April 18/19, 2018, at the Bogoliubov Laboratory of Theoretical Physics at the Joint Institute of Nuclear Research, Dubna, Russia. Former coworkers and followers (see Figure 5) contributed with talks:

The organizers decided to collect contributions to prepare this Special Issue. Following the open call, there were, in addition to the contributions from the above speakers, also contributions from colleagues who could not participate in the seminar: ȱ ȱ

**Figure 1.** Photo taken on April 18, 2018, at the honorary colloquium for D. N. Zubarev's 100th birthday. From left to right: Vladimir Morozov (MIREA, Moscow), Heidi Reinholz (Rostock), David Blaschke (Wroclaw and JINR Dubna), Nikolay Plakida (JINR Dubna), Gerd Röpke (Rostock), Yurii Rybakov (RUDN, Moscow). Background: Hermann Wolter (Munich).

We will now outline the biography and scientific legacy of D. N. Zubarev; for details see [1–3].

D. N. Zubarev studied physics at Moscow State University. In 1941, he graduated from the Department of Physics. His academic advisor was N. N. Bogoliubov, who was also the promotor of his PhD thesis work. From 1954 to the end of his life, D. N. Zubarev worked at the V. A. Steklov Institute of Mathematics of the Russian Academy of Sciences. From 1969 to 1971, he was also head of the Statistical Mechanics and Theory of Condensed Matter Group at the Laboratory of Theoretical Physics, JINR, Dubna. He died in Moscow, July 29, 1992, after a traffic accident.

D. N. Zubarev successfully contributed to statistical physics. In 1957, he obtained, together with N.N. Bogoliubov and Yu.A. Tserkovnikov, the asymptotically exact solution of the BCS model Hamiltonian [4], which was an essential contribution to the theory of superconductivity.

**Figure 2.** Photo taken at an excursion to Mzcheta during the Tiflis Conference on LowȬ Temperature Physics in 1959. From left to right: Dmitry Vasil'evich Shirkov (JINR Dubna), Dmitrii Nikolaevich Zubarev (Steklov Inst. Moscow), Anatoly Alekseevich Logunov (JINR Dubna), Yurii Aleksandrovich Tserkovnikov (Steklov Inst. Moscow), Zygmunt Galasiewicz (JINR Dubna & Wroclaw), Albert Nikifirovich Tavkhelidze (JINRDubna).

ȱ ȱ

**Figure 3.** Photo taken when the group of D. N. Zubarev visited Vladimir in June 1969. From left to right: John Shepherd (UK), KarlȬHartmut Müller (GDR), Celia Shepherd (UK), Wolfgang Götze (FRG), Gerd Röpke (GDR), Dmitrii Nikolaevich Zubarev.

He considered himself as a "father of methods", in particular he published the highly cited review article entitled: "DoubleȬtime Green Functions in Statistical Physics" [5], and wrote the well known monography "Neravnovesnaya statisticheskaya termodinamika" [6], translated from Russian to English by P. J. Shepherd. He made very fundamental contributions to statistical physics published in many scientific articles, based on a sound mathematical approach. His very general approach to nonequilibrium processes with applications in different fields was presented in the Monography [7].

**Figure 4.** D. N. Zubarev at the 6Ȭth Winter School on Theoretical Physics in Karpacz (Poland) 1969. From left to right, back row: Nikolay Maksimilianovich Plakida, Elmar Grigorievich Petrov, Dmitrii Nikolaevich Zubarev, ?, WÙadysÙawa Rybarska (Nawrocka); front row: ?, Tadeusz Paszkiewicz, Jerzy St¿ïlicki, Andrzej P¿kalski, Valery Leonidovich Pokrovsky.

As a leading scientist in statistical physics, D. N. Zubarev had many active collaborations within the former Soviet Union and abroad. Many close relations to colleagues and guests were longȬstanding and are determined by his openȬminded, tolerant and clear scientific position, also his accurate and precise work and discussions. He attracted and educated young scientists, including G. O. Balabamyan, V. P. Kalashnikov, V. G. Morozov, T. Paszkiewicz, N. M. Plakida, L. Pokrovsky, S. Tishchenko, M. V. Tokarchuk and others. He also hosted guests from abroad (see Figure 3), and visited them to give series of lectures, like at the Karpacz Winter School in Poland 1969 (see Figure 4) and at the Miniworkshop on Quantum Statistics in Ahrenshoop (GDR) in 1987 (see Figure 5).ȱ ȱ

**Figure 5.** D. N. Zubarev and M.V. Tokarchuk during a visit at the University of Rostock in November 1987, when Dmitri Nikolaevich was giving a lecture series on the NSO method during a Miniworkshop with the group of Gerd Röpke in Ahrenshoop.

The personality of D. N. Zubarev was formed also by the WWII. On June 25, 1941 he volunteered for duty in the Eighth Division of the People's Militia and participated in the defense of Moscow. At the end of the war D. N. Zubarev was in Berlin with the 47th Army of the First Belorussian Front. He was awarded the Red Star for participation in mine clearing in Berlin. Many of his fellow students died during the war. After war, he worked with G. Hertz who was made head of Institute G, in Agudzery, about 10 km southeast of Sukhumi and a suburb of Gulrip'shi, on separation of isotopes by discussion in a ow of inert gases. After this he worked for several years on important defense problems at the "object," now known as ArzamasȬ16. His association during this period with N. N. Bogoliubov and A. D. Sakharov greatly influenced his scientific career. His wife, Galina Rudolfovna, participated in the Leningrad blockade.

Despite the very hard history, and under the restrictions of the soviet time, he developed an openȬminded and complaisant atmosphere in the contact with physicists around the world. D. N. Zubarev had an unusual talent for social intercourse, which attracted people to him. He exhibited the traits of a true Russian intellectual live interest and openness to anything new in science and in life, honesty and fairness, softness, delicacy, unselfishness and constant readiness to help people, but at the same time he was strict and uncompromising in the search for scientific truth and he unfailingly adhered to strict scientific ethics.

D. Blaschke, A.V. Friesen, V. G. Morozov, N. K. Plakida, G. Röpke. Wroclaw, Dubna, Moscow, Rostock, in July 2020

**Figure 6.** Photo taken at the honorary colloquium for D. N. Zubarev's 100th birthday in the Conference Hall of the Bogoliubov Laboratory of Theoretical Physics at the JINR Dubna. From left to right: D. Blaschke (Wroclaw & JINR Dubna), H. Reinholz (Rostock), V.G. Morozov (MIREA, Moscow), G. Röpke (Rostock), N.M. Plakida (JINR Dubna). Background: Bust of N.N. Bogoliubov.

#### **References**


*2.1. Development of a Proficient Regeneration Protocol*

Unfurled leaves from six field-grown elite sugarcane genotypes (CPF-246, US-127, HSF-242, US-778, HSF-240, and US-64) were sacrificed to develop leaf roll discs, and subsequently placed on callus induction medium. Of six genotypes, maximum embryogenic cells were recovered from genotypes US-127, US-778 on MS medium supplemented with 2,4-D (2,4-Dichlorophenoxyacetic acid) ranging from 3 to 5 mg/L. Five-week-old dark proliferated calli were subjected to many combinations of hormones (RMOS, RMSD, RMSDB, and RMSDBK) (Section 4.2) and the maximum number of shoots was observed on RMSDBK medium (Figure 1). However, it was observed that maintenance of 2,4-D in combination with kinetin and BAP (6-Benzylaminopurine) results in healthy and separable mature plants, contrary to earlier studies (Figure 2) [14,15]. BAP, kinetin, and 2,4-D had synergistic effects on shoot regeneration [16,17].

**Figure 1.** Efficient multiple shoot regeneration from embryogenic calli developed from undifferentiated young leaf whorls of different cultivars of sugarcane on the RMSDBK medium. (**A**) US-778 (**B**) HSF-240 (**C**) US-64 (**D**) CPF-246 (**E**) US-127 (**F**) HSF-242.

**Figure 2.** Effect of different types of media on shoot induction from calli derived from young leaf whorls of different genotypes. Most responsive genotype to regeneration was CPF-246 on RMSDBK medium.


*2.3. Materials*

2.3.1. Self-Report Questionnaires

The materials included two psychometrically self-report questionnaires:

(1) Depression Anxiety Stress Scales (DASS-21), which consists of 21 questions with 7 items for each scale (e.g., for anxiety, "I feel I am close to panic"; for depression, "I cannot experience any positive feelings"; for stress, "I find hard to wind down"); all subscales are rated on a four-point Likert scale ranging from 0 (never) to 3 (almost always).  Higher total scores indicate more frequent self-reported memory difficulties (max–min total score: 80–16) [61].


**1. Introduction**

Road transport is the most common transportation form globally. Road transportation provides benefits both to nations and to individuals by facilitating the movement of goods and people. It enables increased access to jobs, economic markets, education, recreation, and health care, which in turn have direct and indirect positive impacts on the health of populations [1]. However, driving on roads is a complex task that involves extensive interactions between road users and the other components of the transport system, such as the driver, the vehicle, and the road traffic environment [2]. This interaction, if well-coordinated with appropriate road signs, effective drivers' road sign education and comprehension, can result in smooth flow of traffic, enhanced road safety and a general reduction in traffic violations and accidents [3]. However, it has been reported that over 1.2 million deaths and about 50 million non-fatal injuries result from road accidents globally on an annual basis [1]. The global cost of road accidents has been estimated to cost the world economy USD 1.8 trillion between 2015–2030 or 0.12% of global Gross Domestic Product [4]. In a bid to reduce this number of deaths, governments around the world are taking different measures depending on the local domestic characteristics and driving behaviors they wish to stop or encourage. Researchers have also undertaken assisting governments by assessing the relationships between various factors and driving safety on roads. Governments respond to bad driving behaviors mostly through punitive measures such as fines to curb bad driving practices. Others have suggested the standardization

**Citation:** Al-Rousan, T.M.; Umar, A.A. Assessment of Traffic Sign Comprehension Levels among Drivers in the Emirate of Abu Dhabi, UAE. *Infrastructures* **2021**, *6*, 122. https://doi.org/10.3390/ cinfrastructures6090122

Academic Editors: Krzysztof Goniewicz, Robert Czerski and Marek Kustra

Received: 30 July 2021 Accepted: 30 August 2021 Published: 31 August 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

of traffic signs internationally to enhance the ability of tourists to drive without further host-country training [5].

The roads in the United Arab Emirates (UAE) are some of the best in the world in terms of quality, as evidenced by their ranking in the road quality index. The UAE roads were ranked ahead of more developed countries such as Germany, USA, UK and France in the 2019 report of the World Economic Forum [6]. Oil wealth has led to the rapid growth and development of Abu Dhabi and its sister Emirates within the UAE arrangement. This rapid economic growth has attracted people from different regions of the world to the UAE with its attendant need for smooth and efficient means of transportation. A large volume of tourists also frequents the UAE annually, reaching over 15 million tourists in 2018 [7]. Some of these tourists prefer to rent cars and drive around on their own in order to get a better feel of the country. While the Emirate of Dubai has introduced the Dubai metro in addition to other modes of public transportation, the Emirate of Abu Dhabi only relies on public buses, taxis, rental cars and private cars for the movement of people. This has led to pressure on residents to own a personal car to ease movements from point to point. With so many drivers from diverse backgrounds and driving educations, the situation is ripe for traffic violations and accidents.

The police in Abu Dhabi issued five million fines against drivers in 2019 [8], with a population of about 2.9 million (2016 estimates from Statistics Centre of Abu Dhabi (SCAD)); this translates to 1.7 fines for every resident. Despite the increased volume of fines against drivers, it has been found that road traffic injuries in the UAE remained stable from 2012 to 2016 [9]. Another alarming factor in the road injuries and fatalities is the overrepresentation of UAE nationals among the fatalities and the injured [10]. One study of five countries within the Gulf Co-operation Council (GCC) found that the drivers correctly comprehended only 56% of the traffic signs they were presented [11]. The authors also found that for the UAE in particular, the respondents (N-861) correctly comprehend only 62% of the traffic signs presented to them. They attribute the poor performance to the manner in which drivers are licensed and the laxity of the assessments. Similar studies carried out in the United States by Ward et al. [12] also found that drivers could not comprehend a large percentage of the international road signs they were presented. In Turkey, Yakut [13] found that on average, participants correctly identified 81% of the signs presented. In Kano city, Nigeria, it was found that the average traffic sign comprehension level was as high as 79%, with the least comprehension being 54.7% on the "Park and Ride" sign. However, they found that truck drivers had a lower understanding level than all other classes of road users [14]. A study of drivers' sign comprehension across four countries (Poland, Finland, Canada and Israel) found that on average the drivers identified 58.5% of the signs correctly [5]. This goes to show that the problem is not limited to developing countries only, developed countries are also struggling.

A recent study of road crashes in Abu Dhabi between 2012 and 2017 revealed that there were 1.26 million crashes, 9327 injuries, and 1305 fatalities during the period covered. The study went on to reveal that the crashes tended to be fatal when collisions occurred between 22:00 and 5:59 o'clock, occurred under adverse weather conditions, involved pedestrians or drunk drivers, occurred on higher speed limit highways, as well as when drivers were male, minors and/or Emiratis [10]. The economic costs of these accidents to the GCC have been estimated to be around \$7.5 billion annually [15]. While the police attempt to use fines to correct poor driving behaviors, governments, on the other hand, focus on road improvement projects. Little attention has been paid by governments in assessing drivers' knowledge and comprehension of traffic signs, which facilitates and enhances safety and better road use compliance. The situation is further compounded due to today's travel culture where people are often licensed in one country and then drive without any further training or assessments in another country [5]. This happens to be the case across the GCC where Americans and Europeans seldom undergo any assessments but are issued licenses upon presenting their home-country drivers' licenses. A good understanding of traffic signs assists drivers in proper use of roads, contributes to the

smooth flow of traffic and enhances safety. Therefore, this study seeks to assess the level of road traffic signs comprehension among drivers in the Emirate of Abu Dhabi.

#### **2. Literature Review**

Road traffic signs help regulate traffic, provide crucial visual guidance, can alert drivers to potential hazards on the road and give drivers important preview time during night-time conditions [16]. In addition, well placed and maintained traffic signs provide drivers with clear guidance that enables them to act in a timely manner in accordance with the displayed instruction. Poorly maintained and illegible road signs can cause travelling delays and increase the potential for accidents for road users, especially drivers using such roads for the first time. Poorly maintained road signs are a growing problem even in developed countries. For instance, European Union Road Federation (ERF) [16] reported that 33% of Germany's 25 million road signs are considered non-readable, while another 25% are older than 15 years. Traffic signs come in both text and symbols, while in some instances may be text alone or a symbol alone. Researchers have assessed which option is more effective in delivering the required message to drivers. While it was found that text signs were difficult to comprehend by tourist respondents in Thailand [17], in Israel, a combination of text and symbols was found to be more acceptable and reduced driver comprehension time [18].

Past studies have also found that personal and social factors significantly affect drivers' comprehension of road signs [5,11,17,19,20]. In the case of Al-Madani and Al-Janahi [11], in their comparison of the countries within the GCC, they found that the drivers' education level, income range and nationality affected their ability to correctly identify traffic signs. Interestingly, they also found that males had a better comprehension than females and western drivers performed better than their Arab counterparts did. In Thailand, Choocharukul and Sriroongvikrai [17] assessed tourists in the country and found that drivers' age, experience in a foreign land and their nationality had a significant impact on ability to comprehend and translate road traffic signs. In the case of Shinar et al. [5] who assessed comprehension across four countries (Canada, Finland, Israel and Poland), they found that the age, gender and country (nationality) all had a significant impact on the comprehension levels of the respondents.

Taamneh and Alkheder [20], in their study of Jordanian drivers, found that only 61% of the drivers comprehended regulatory signs, 66% of drivers comprehended warning signs and 75% of drivers comprehended guidance traffic signs. They also found higher comprehension levels among drivers holding a commercial driving license and drivers with driving experience of more than 11 years.

Kirmizioglu and Tuydes-Yaman [21], in their study in Ankara-Turkey, found that out of 39 signs, only 12 were recognized correctly by almost 70% of the participants. They further found that over 10% of the drivers comprehended five of the signs oppositely, and they argued that the implication of this was riskier than not knowing at all. In Iraq, Ismail [19] found that drivers' comprehension of traffic signs increased with increasing education levels, the urbanization level of his residence and daily driving practice. Males and private car drivers were found to have a higher comprehension than females and other driver categories, respectively. He also found that marital status had no significant effect on the comprehension level of drivers. Ou and Liu [3] studied the influence of sign design features and training on the comprehension of 65 selected Taiwanese traffic signs on Taiwanese and Vietnamese drivers. They found that training outcome was positive in both user groups. The average comprehension improved from 0.63 and 0.41 pre-training to 0.98 and 0.89 post-training for Taiwanese and Vietnamese drivers, respectively. More importantly, comprehension scores measured after one month remained higher than pre-training.

Traffic signs are a simple and cost-effective intervention that can yield impressive rates of return in terms of road safety, and thus reducing the socio-economic consequences [16]. The European Union Roads Federation's review revealed that having good signage reduced fatalities by up to 87% in the UK. In Norway, the value derived from improved traffic

signs was found to outweigh the costs by a factor of 3.5:1 [22]. While in Australia, its National Black Spot program was estimated to have reduced fatal and casualty crashes at the treated sites by 30%; the report went on to reveal that traffic sign interventions had the best cost-benefit ratio, ranging between 15:1 and 20:1 depending on the financial hypothesis made on the project [23].