Hot Spot Analysis and Development Trend of Intelligent Roof Parking Lot: Bibliometric Analysis Based on CiteSpace Visualization Software

Wen HUANG, Zenan CHEN, Jianfeng XIE

Jiangxi Normal University, Nanchang 330200, China

Abstract Using CiteSpace visualization software, literature research on roof parking lot in recent 20 years is analyzed, and the research direction and development of the relevant papers are integrated and induced. From utilization development, roof greening and technical practice, overall consideration and grasp of the feasibility of roof parking lot are conducted. Realization paths of two kinds of roof parking lots are provided: suspended PRT stereo parking lot and telescopic rail elevator, and it is committed to providing feasible suggestions and reference for future roof parking lot.

Key words CiteSpace visualization software, Roof parking lot, Lifting and lowering device

1 Introduction

With the development of cities, the surplus of urban land is decreasing, and the number of cars is increasing. Urban "parking difficulty" has become a common problem in major cities of China, which is manifested in the huge gap between the actual parking spaces and registered vehicles. Generally speaking, the number of urban parking depends on the overall land area and the overall building density. On the premise that the overall land area and the overall building density remain unchanged, in order to maintain a large number of cars and have enough parking spaces, it needs to consider the development and utilization of the underground part or the roof part of the building. Meanwhile, from the perspective of improving the using efficiency and convenience of parking lot, the development trend of parking lot in the future is making the parking lot intelligent. In February of 2002, the

AKT

2000

Intelligent

Parking

System

was issued in the Security and Safety Technology Magazine and firstly provided a specific implementation method for the intelligent parking lot. At present, more and more attention has been paid to the research of intelligent parking lot, and the research contents and types are gradually enriched. However, there is no case literature on the application of intelligent parking lot to the roof. Under the background of relatively perfect development of underground parking lot, it is of great value to carry out qualitative and quantitative evaluation in the field of roof parking lot from a scientific point of view. Additionally, there is no comprehensive summary and analysis of the existing related literature. In this paper, a comprehensive and systematic search of all relevant literature on intelligent parking lot and roof is conducted, and the feasibility study results on the combination of intelligent parking lot and roof are extracted and combed for quantitative analysis. The research aims to provide an overall overview of the macro and overview of hot spots for applying intelligent parking lot to roof, thereby solving the problem of "difficult parking".

2 Data source

2.1 Search criteria

(i) All the literature on intelligent roof parking lot is searched, not limiting the format, the issued journal and language of literature; (ii) the theme is intelligent roof parking lot, or roof renovation based on parking lot; (iii) the purpose of this study is to reconstruct the roof without affecting the basic functions of roof facilities.

2.2 Exclusion criteria

(i) The research object is parking lot. Although the status quo of parking difficulties and huge investment is analyzed, and its effect of alleviating the problem of urban parking difficulty is analyzed, the results only contain traditional inside and outside parking and underground parking, causing that it is impossible to study the intelligent roof parking lot; (ii) the literature taking renovation of roof facilities as the theme, but not reporting roof parking function; (iii) the literature issued only with abstract or news and commentary form, but not providing specific contents and implementation methods of the study; (iv) for multiple duplicate literature published by the same author, the article with the most complete data is included, the order of priority is dissertation > journal paper > conference paper.

2.3 Literature search and screening

Via CNKI, related papers taking "intelligence" as the theme and containing "parking lot" are retrieved, and search period is from January 15, 1997 to March 20, 2021, and 1 965 papers are searched in total. Moreover, the international published literature that topics or keywords are related to the research of intelligent roof parking lot are systemically collected. Via screening, the repetitive literature, news and comments that do not belong to the research field of this article are eliminated, and 220 papers corresponding with basic requirements are obtained. Then, the content of the literature is further studied. Via manual screening, 36 papers are obtained finally. Using CiteSpace visualization software, knowledge map analysis is conducted, and quantitative description of intelligent roof parking is conducted. The research of intelligent roof parking lot is analyzed and visualized in an integrated and comprehensive way, and literature analysis is further carried out, and main topics of intelligent roof parking are deeply explored and systematically elaborated.

3 Research methods and ideas

Bibliometric is an important method to explore the knowledge framework of a certain field, and a quantitative method of research literature. By showing as different types of network maps, a specific research area is displayed, and it plays an important role in showing the research status of the field, identifying the important journals and scholars in the field, and tracking the dynamic evolution trend of the field development, and has obtained wide attention and recognition of academic circles. Compared with traditional review method of expert evaluation, bibliometric research method has obvious advantages in these aspects: (i) the research scope and time span of bibliometric method are wider, which could accommodate a larger number of literature and related research topics; (ii) bibliometric method is not limited by professional knowledge; (iii) bibliometric method can mine and show more information of research literature.

Using bibliometric method, literature characteristics, knowledge mapping and hot spot dynamic research process of intelligent roof parking lot are analyzed. The literature characteristics such as milestone literature, important authors, main institutions and regions in the research field of intelligent roof parking lot are found, and research hotspots and dynamic evolution in this field are studied, and future research focus and core literature in this field are explored, to provide valuable enlightenment for future research direction in the field.

4 Data analysis

4.1 Time distribution of literature

To grasp the quantity change of literature on intelligent roof parking lot on the whole, 36 related papers are statistically analyzed firstly. According to Fig.1, the number of literature in the field of intelligent roof parking lot generally has a rising trend of fluctuation. The literature record began in 1994, which somewhat lagged behind the birth time of roof parking lot, and corresponded with the law of literature research publication. With the development of the city, the surplus of urban land is decreasing, and the number of cars is increasing. At the same time, because of the high cost of building indoor parking lot and outdoor ground open parking lot, and occupying a lot of indoor and outdoor space, it is difficult to park in modern society and the huge investment in building traditional parking lot. Therefore, it could improve utilization rates of urban land and buildings, and realize that intelligent roof parking, which is convenient, efficient and highly automated, has been studied and concerned by scholars, making that the research on intelligent roof parking lot is increasing.

Fig.1 Analysis on the general trend of research literature on intelligent roof parking lot during 1997-2021

4.2 Distribution of institutions with more published articles

During 1997-2021, Jilin Jianzhu University and China Architecture Design & Research Group published the largest number of literature, accounting for 5.56% of all literature in this field. Fig.2 shows distribution of institutions with more published articles.

Fig.2 Distribution of institutions with more published articles on intelligent roof parking lot during 1997-2021

4.3 The source of journals with more publications and the situation at home and abroad

Seen from journal sources of related literature, 36 papers have been issued on 32 kinds of publications. Among them, four papers are from the

World

Architecture

Review

, and two papers are from the

Architecture

Technique

, and others are from 30 different journals. In 36 papers, there are nine foreign papers, and they are from the

Structural

Engineering

International

, the

Design

, the

World

Architecture

Review

, the

Stahlbau

, the

Environmental

Engineering

Research

, and the

Journal

of

Civil

Engineering

and

Management

. Although there is much literature in China, most of them are about the imagination and design of roof parking lot, while most of the foreign literature is about concrete examples and applications. In 1997, some scholars in China published relevant articles to introduce the application of foreign roof parking lot. With economic development, the roof parking lot will be widely used in China. Additionally, China has little cooperation with other countries. With the gradual promotion of roof parking in China, domestic scholars should constantly sum up their experience, strengthen exchanges and cooperation between countries, and make their own voice in the international academic community. The top five journals with the largest number of articles published from 1997 to 2021 are shown in Fig.3.

Fig.3 Source distribution of research literature on intelligent roof parking lot during 1997-2021

4.4 Hot spot analysis

Keyword is an important part of literature, reflecting the main essence content of the article. Via analysis of keyword co-occurrence network, it could effectively reflect research hotspots in subject field. Via measurement visualization analysis on the selected 36 papers, three clusters of high-frequency keywords are obtained, and nodes with the same color belong to the same cluster (Fig.4).

Fig.4 Analysis of hot spots in the research literature of intelligent roof parking lot during 1997-2021

4.4.1

Cluster 1. It is roof utilization and development based on urban economic development. Main key words contained by the cluster are urban economy, urban development, space utilization and urban public space. The content of cluster mainly reflects the scholars’ attention to the economic benefits of roof parking lot. Roof space is a kind of urban space with great potential. The planning and utilization of roof space is an effective way to alleviate the lack of urban space, which has been widely applied at home and abroad. Since China’s reform and opening up, the economy has developed rapidly, and urban land has been increasing. Each city presents a situation of high land price and less available land. As an important building functional component, roof space has important significance in urban development, but it is often neglected in design. Most buildings only look at the roof from the functional point of view, to meet the requirements of thermal insulation, waterproof and the installation of construction equipment, and rarely use its characteristics to expand the scope of economic activities. Among them, the development of parking economic activities is mainly roof parking lot. Roof parking lot has the advantages of saving investment and land use, but it has not been generally recognized by consumers in China. The actual use effect of built projects is poor, which is related to people’s concept of pursuing convenient life. This can learn from foreign experience to optimize the design, set up mechanical automatic parking system, and shorten the parking time. In big cities, roof parking can also be guided by reducing parking fees.

4.4.2

Cluster 2. It is the relationship between roof parking lot and roof greening. Keywords contained by this cluster contain green landscape, landscape design, roof greening, roof garden, and roof waterproof. The keyword nodes in the cluster are generally large, illustrating that the weight is larger, and the attention degree of research focus is higher. In the modern cities that land is scarce, it is unrealistic to expand a large number of garden green space, while the construction of ecological city and sponge city is the pursuit of Chinese cities. In recent years, the "green roof" developed in China is a kind of green "regeneration space" sought from various buildings that have been been built in large quantities and are still under construction in the cities. Roof greening is an important trend in current architectural design because of its good ecological benefit. When parking lot is applied to roof, the research displays that it could destroy the ecological benefit. How to seek the combination of parking lot and green, and simultaneously meet the use and ecological benefits? Some scholars put forward that lawn grid is a kind of product with environmental affinity, which not only solves the parking problem, but also beautifies the environment. Compared with concrete mesh brick, its greening rate is greatly improved, reaching 90%, and its load capacity reaches 200 t/m. Its special design makes installation fast, simple, easy to move, high pressure resistance, UV resistance and no pollution to the environment, which could be widely applied in constructing temporary parking lot, footpath, ground around factory and residential buildings, green belt around sports ground, wall of buildings and roof greening. But the concrete effect still needs to be put into practice.

4.4.3

Cluster 3. It is implementation of technology related to roof parking lot. Main keywords contained by the cluster are parking unit, water curtain system, automation, lifting and lowering device, lightning protection design, and waterproof. At present, thousands of roof parking lots have been put into use in China, but most of them have various problems. First, roof leakage. The roof of roof parking lot is special. Its dynamic load, impact load and vibration are far greater than ordinary roof, and its waterproof design can not be equal to ordinary roof. As there is no specific requirement in the national standard, most of the architectural designers still carry out the waterproof design of this kind of roof according to the traditional roof waterproof design code. Second, in some shopping malls with conventional lightning protection design of roof, when the lightning protection facilities of surrounding buildings can not effectively protect the cars parked on the roof, the car was struck by lightning. How to do the lightning protection design of roof parking lot has become the concern of building electrical designers. Additionally, the intelligent control system, automatic control system, lifting and lowering design and other related key technologies still need to be further studied.

4.5 Development trend of intelligent roof parking lot

Emer-gent index in keywords is studied based on CiteSpace visualization software, and appropriate emergent words are selected to describe research development trend in recent years. Combining research hotspots (Fig.4) and emergence index in keywords, it could be found that current intelligent roof parking lot mainly shows below three research trends.

4.5.1

Study of stereo parking system based on suspended PRT. In emergent indexes of keywords, emergence intensity of PRT stereo parking system is higher, which is also embodied in co-occurrence network of keywords in Fig.3. Suspended PRT stereo parking is a kind of new stereo parking area based on suspended PRT transportation technology, which combines specific parking environment of parking area. It forms network from PRT air orbit, thereby forming single-storey PRT system parking lot, which could park the vehicle in the air. According to track height, PRT system parking lot with multi story is set up, and the vehicle is parked on the PRT parking grid on each floor. Using prominent advantages of suspended PRT transportation technology, roof space could be selected for parking, which not only sufficiently uses air resources but also has the advantages of economy and environmental protection. The setting of stereo parking lot based on suspended PRT does not occupy ground resources and carries out rationalized design, provides an optimized design scheme for the problem of "parking difficulty", and a new research direction for easing the decreasing land resources and the development of parking lot.

4.5.2

Study based on design of telescopic rail elevator. The emergence intensity of telescopic rail elevator is also very high, with consistent continuing time with intelligence, construction technology and design research. The telescopic rail elevator can lift the car to the corresponding height, so as to achieve roof parking, and the elevator system consists of lifting system and operating mechanism. Among them, the lifting system and a set of running mechanism are assembled on the steel structure underframe to form a hanger; the truck crane box suspended by steel wire rope is used as lifting appliance; another set of running mechanism is assembled on I-beam as movable track. The working principle of the lifting mechanism is that the motor drives the double output shaft reducer, drives the drum through the intermediate shaft, and at the same time rolls up the steel wire rope to lift the truck crane box. The working process of the whole system is as follows: the car enters the truck crane box, and the car is manually fixed on the truck crane box. Starting the lifting motor, the double output shaft reducer is driven through the coupling, and then the drum is driven to rotate through the reducer and brake wheel coupling, so that the four steel wires fixed at the four corners of the car are wound on the drum synchronously through the fixed pulley, to ensure the stable rise of the truck crane box. When the truck crane box reaches the required lifting height, the running mechanism on the hanger works to lift the truck between the active and passive wheel groups of the movable track. After that, starting the running mechanism of the hanger to the required position, the truck crane box is put down, and the truck is driven away, and the lifting process is completed. The process of car lifting from the roof yard to the ground is the opposite.

5 Conclusions and suggestions

Worldwide, the research on intelligent roof parking lot is on the rise. Seen from research institutions, the study on intelligent roof parking lot is dominant by university and architectural design and research institute. In top 10 research institutes, Jilin Jianzhu University and China Architecture Design & Research Group are dominant, followed by other institutions. Via CiteSpace bibliometric analysis, hot spot analysis related to roof parking lot in recent 20 years is studied, and most of them focus on the utilization and development of the roof, the relationship between the roof and greening, and how to realize the roof parking technology. The relationship between the three is not contradictory. Due to the open nature of city roof, it can be used as a roof parking lot, and keep the city green, and the related lifting device can also make profits through patent application. But for current domestic situation, the application of urban roof parking lot is relatively small.

To realize large-scale application of roof parking lot throughout the country, it also needs many technical practices and studying the possibility of broadening space utilization of urban roof when maintaining the roof greening and beauty. It can refer to Chongqing of China, obtaining reference in the three-dimensional use of urban space. At the same time, more scholars are needed to invest in this work and research, so as to make suggestions for the continuous improvement and implementation of roof parking, improve the utilization rate of urban space as soon as possible, and solve the problem of urban parking difficulty.