1. Introduction
Cities are here to stay, and the future of cities is the future of humanity. The departure of some residents from major cities in the early stages of the new coronavirus pneumonia epidemic was a temporary response that will not fundamentally change the global urbanisation process. The pace of urbanisation throughout the world will continue to accelerate over the next 30 years: the world urbanisation rate is expected to increase from 56% in 2021 to 68% by 2050. This will mean an additional 2.2 billion people living in cities, mainly in Africa and Asia. Urbanisation levels are expected to increase further across the globe, although urban development in highly urbanised and more developed regions will enter a period of stabilisation or deceleration.
The street plays a pivotal role in a city [
1], not only as an important public space for the city, but also as the primary place in which citizens conduct commercial activities. It can not only meet people’s daily consumption needs for shopping, leisure, and other functions, but also can provide a good activity location for rest and entertainment for city residents. The spatial quality of commercial streets has a direct impact on the living environment and quality of residence of residents, and its importance is self-evident [
2], so it has received widespread attention. The street environment is one of the most important factors influencing the quality of a street. The traditional transformation of streets by top-down government-led design no longer meets the needs of the population, which requires designers to consider more factors when carrying out street transformation. This paper combines the results of research related to the field of study and abroad to analyse and summarise the factors influencing the design of commercial street space, summarising the interrelationships between the indicators and the quantitative criteria, at the same time building up a comprehensive evaluation model. It is necessary for the designers to place themselves in the position of the users, to compare the specific uses of the street space at the beginning of the design phase, to further understand the operation of the street and the subjective evaluation of the users so as to examine whether the use of the street meets the design expectations, and to provide effective feedback for the improvement of the quality of the street in the future.
1.1. Urban Regeneration and Street Renewal
Urban regeneration is a comprehensive, holistic, policy-oriented, and strategic social system project. It is a government-led urban regeneration effort [
3] whose main objectives are to improve the living environment, protect and improve people’s livelihoods, promote the upgrading of urban industries, improve urban functions, adjust the urban structure, enhance urban vitality, preserve cultural traditions, enhance urban quality, promote harmonious social development, and promote urban civilisation. The study of urban regeneration originated from the desire to solve urban problems such as the decay of old urban centres and the poor living environment; to address these problems, urban regeneration theories such as organic regeneration [
4], systematic regeneration, and sustainable development were proposed [
5,
6,
7], spanning from the initial residential regeneration to neighbourhoods and commercial areas, making urban regeneration more representative.
At the beginning of the 14th Five-Year Plan in China, the transformation of the old method of urban development led to new requirements and a clear positioning of the concept of “organic renewal” in cities. Street space is one of the most important factors affecting the overall competitiveness and public satisfaction of a city. The quality of street space has become a new issue for urban public space, as urban liveability places higher demands on street space and highlights the need to improve the quality of street space to stimulate urban vitality and promote sustainable urban development. It has been extensively researched by scholars worldwide, but research has mostly focused on quantitative feature-based and topological relationship analysis [
8,
9,
10]. As Chinese scholars continue to study spatial syntax and urban street patterns, more and more scholars have begun to focus on the integration, intelligence, and depth of streets [
11,
12,
13], trying to reveal the complex socio-economic activities between streets and buildings and the deep relationships behind them. In commercial streets, speed reduction is used to increase pedestrian safety [
14], while pedestrians are given a free path to pass through in order to strengthen the synergistic links between buildings on both sides of the road and the transformation of the street into a public space.
1.2. Factors Influencing Street Quality
The discussion of the quality of commercial street space is broadly divided into two categories, namely the discussion of street space quality indicators and the assessment of street space quality. The former focuses on the description of the relationship between various elements and functions in the physical environment, while the latter focuses more on the analysis of the state and psychological feelings of people in the course of their behavioural activities. The study of spatial quality indicators refers to the identification of factors that influence the quality of a street and their quantitative evaluation through modelling, quantitative statistics, and objective judgement. Based on a summary of the literature, Sun Ruifeng et al. established a database for quantitative research on street space quality based on multiple sources, such as spatial morphological data and streetscape pictures, and constructed a street space quality evaluation index system based on two dimensions: material space composition and subjective space perception [
15]. The composition of street space includes the economic and technical indicators of buildings on both sides of the street, public service facilities [
16], the street environment [
17], and traffic capacity [
14], etc. Different elements of the composition of street space have different bearing capacities and different levels of attractiveness within the street space, which in turn affects the quality of street space. The subjective perception of street space consists of three main indicators: street safety [
18], comfort [
17], and sociality [
19].
The built environment in 21st-century cities is facing serious challenges, not only in terms of redesigning the physical environment, but also in terms of reshaping public space into a more suitable location for walking and social interaction. High connectivity values and rich diversity are among the most important features of the built heritage, reflecting the character of a building’s façade while eliciting tranquillity, aspiration, and well-being. Inhibitors of walkability are associated with poor-quality and narrow pavements, cars parked on the pavement, dirty streets, and motorised traffic and vehicle noise, which lead to negative emotions in the perception of walking, such as fatigue, anger, disgust, discomfort, and insecurity, which negatively affect the well-being of residents, depending on age and gender [
20].
The above influences are the basic framework for the quality of the street, considering that the renewal of the street has other characteristics, such as the type of structure, especially the harmonious relationship between old and new buildings, and the need to satisfy the human perceptual psychological evaluation and rational design approach [
21]. In turn, the visual perceptions of people in the street need to be considered, and the important influence of the visual perception of the street on urban planning has been studied in terms of street space, vertical interfaces, decorative elements, and colour aesthetics, which can help to improve the quality of life of residents [
22]. Meanwhile, Cheng Liang also analysed the visual perception of urban streets in Jianye District, Nanjing, China, using streetscape images and proposed four indicators for evaluating the visual perception of streets, including significant area saturation, visual entropy, the green landscape index, and the sky openness index [
23]. Defining a framework for assessing the walkability of a city can highlight the strengths and weaknesses in its urban environment. All aspects that have a direct impact (evidence-based) on promoting the adoption of healthy lifestyles or promoting active transport should be considered [
24].
1.3. Street Quality Assessment
There are many different kinds of people living in streets, and quality improvements to street spaces affect different people and need to be analysed for different research perspectives, such as children’s health [
25], elderly health [
26], and the post-epidemic era [
27]. All of the various evaluations relate to populations, human spatial perceptions relate to health gains, and road area ratios are weaker than other indicators. The evaluation of different urban functions can be biased. Among the existing methods, the use of the quantitative analysis of street quality is quite well established, and various methods have been developed, such as streetscape imagery [
28], Open Street Maps (OSMs) [
29,
30], satellite imagery, and remote sensing methods [
31]. All of these have used different methods to analyse the various elements of street quality and have accumulated a number of indicators that can be used to evaluate street quality. These methods use streetscape images, POI data, or map data to record three-dimensional city profiles and user interactions from a human perspective, but, in practice, there are certain problems; for example, the development of indicators and the differentiation of conditions are more dependent on people’s subjective judgement [
32], the relationship between the factors affecting the spatial quality of the street is not clear, and the focus between the factors is not clear. This paper proposes and establishes a set of spatial quality evaluation systems for urban street space planning and design.
The evaluation of street quality based on these data is generally based on the local state of the street and a quantitative analysis of street quality, and lacks other influencing factors of street quality (such as street comfort and street attractiveness), requiring street users to evaluate street quality subjectively and thus intuitively feel the influencing factors of street quality. However, there is currently no comprehensive theoretical system for evaluating the quality of urban streets, and there is a lack of corresponding methods and technical support. In addition, the evaluation of the effectiveness of street quality improvement measures in China is rarely addressed. In this paper, by drawing on relevant research results at home and abroad, we design a quality improvement transformation plan and a corresponding street quality index system suitable for the actual situation in China, and we carry out research on the evaluation of street quality improvement. Specifically, hierarchical analysis and the entropy method are used as research methods to evaluate the street quality, and optimisation strategies are given based on the evaluation results.
Our paper is organised as follows.
Section 2 reviews the current situation in the study area and the establishment of an evaluation indicator system based on relevant requirements and a questionnaire survey.
Section 3 describes the recovery of the questionnaire data and conducts the analysis and discussion.
Section 4 summarises the conclusions.
3. Results and Analysis
A total of 276 open-ended questionnaires were distributed, and 258 valid questionnaires were returned, with an effective rate of 93.47%. The proportions of men and women were 46.51% and 53.49%, respectively, with the largest age group being 36–45 years old, followed by 45–60 years old(
Figure 3). Frequency analysis and AHP hierarchical analysis were then performed on the data from 258 respondents. The weight values of each indicator were derived and a consistency test was completed [
49].
3.1. Credibility Analysis
The validity study was used to analyse the rationality and practical significance of the research items. The validity analysis used factor analysis as a data analysis method to examine the status of the data validity level by conducting a comprehensive analysis of KMO values, commonality, variance explained values, and factor loading coefficient values, respectively. This study found that different researchers used different methods of analysis for the same question; there was some variation in the reliability of the data. KMO values were used to judge the appropriateness of information extraction and commonality values were used to eliminate unreasonable research items.
Finally, the reliability coefficient Cronbach’s alpha was used to assess the internal consistency of the obtained factors. This coefficient has been used to measure the reliability of questionnaires with multiple Likert scale questions [
50,
51,
52]. A Cronbach’s alpha value of 0.70 or higher indicates good reliability of the data. A KMO value between 0.8 and 1.0 indicates adequate sampling, while values between 0.7 and 0.8 are still acceptable [
53,
54].
The questionnaire data were imported into SPSS statistical software for factor analysis and reliability testing. From the above table, we can see that the value of Cronbach’s alpha was 0.817, which is above 0.8, thus indicating that the research data had a high level of reliability (
Table 3); the analysis yielded the sample data test statistic KMO = 0.664 with a significance level of
p < 0.05, which passed the validity test and satisfied the applicable conditions of factor analysis (
Table 4).
3.2. AHP-Entropy Weighting Method to Determine Weights
The basic idea of AHP is to first establish a hierarchical structure describing the functions or characteristics of the system according to the evaluation requirements, then compare the relative importance of the risk factors by two and give the corresponding scale to form a judgment matrix of one factor at the upper level to the related factors at the lower level, in order to give the relative importance sequence of related factors to a factor at the upper level. AHP is a useful method for the quantitative analysis of non-quantitative events, especially when the structure of the target factors is complex and the necessary data are not available, and when the evaluator’s empirical judgement needs to be quantified.
The entropy weighting method determines the weight of an indicator based on the magnitude of the information load of each indicator. According to information theory, to examine the role of each factor in the indicator system, the variability of the indicator must be studied. The greater the variability of the indicator, the greater the information content of the indicator and the greater the discriminatory effect of the indicator, i.e., the greater the “differentiating power” of the indicator. This means that the weight of each indicator should be determined by the variation in the attribute values of the options under the indicator; the greater the variation, the greater the weight of the indicator; conversely, the smaller the weight.
3.2.1. AHP Determination of Weights
AHP was applied to determine the subjective weights of the influencing factors.
Constructing a judgement matrix. A judgement matrix represents a two-by-two comparison of all factors under a criterion. In this paper, the nine-scale method is used to construct the judgment matrix. The maximum eigenvalue λmax of this matrix is first found corresponding to the eigenvector wi, and then normalised to obtain the weight vector of risk factors. The evaluation indicators are compared two-by-two using a scale of 1 to 9. The judgement matrix A is as follows.
- 2.
Consistency test. The constructed judgment matrix is tested for consistency, as shown in Equations (2)–(3):
Here, is the consistency index; is the maximum eigenvalue of the matrix; is the order of the matrix; is the consistency ratio; and is the average random consistency index.
If < 0.10, then the judgment matrix passes the consistency test; otherwise, the matrix needs to be readjusted.
The data are brought into the formula to calculate the D1–D14 weight values (
Table 5).
As can be seen from the results in the table, all judgement matrix consistency evaluations met the requirement of less than 0.1 and passed the consistency test.
3.2.2. Entropy Weighting Method for Determining Weights
Using the entropy weighting method to determine objective weights, weights were calculated for the indicator descriptions in
Table 1, and the specific calculation process for the entropy weighting method was as follows.
- 3.
Create a judgment matrix for n samples and m evaluation factors.
Normalise the judgment matrix to obtain the normalised judgment matrix
, as shown in Equation (4):
Here, is the element of the -th row and -th column of the matrix ; is the -th evaluation indicator measure of the -th sample; is the minimum value in different samples for the same indicator; is the maximum value in different samples for the same indicator.
- 4.
Calculate the entropy and entropy weight of the j-th indicator, as shown in Equations (5)–(7):
Here,
is the entropy of the indicator;
is the element of the
-th row and
-th column of the matrix;
is the entropy weight of the indicator. The calculation leads to
Table 6.
3.2.3. Combined Weighting Calculation
The AHP and entropy methods are used to calculate the weights, one for the subjective assignment and one for the objective assignment. The combination is used to calculate the combined weights, as shown in Equation (8):
The AHP-entropy method of determining weights is very adaptable. The integrated weight values of each factor in the scheme layer in the objective were obtained as shown in
Table 7.
4. Discussion
According to the results of the comprehensive weight value determined by the AHP and entropy weight method (
Figure 4), all factors have a positive and significant impact on the residents’ evaluation of the implementation effects of the quality improvement of commercial streets. The importance of evaluation indicators is determined by the overall weighting. Among them, the proportion of street ancillary facilities has the greatest impact, followed by street accessibility, street openness, the vehicle interference index, street facility richness, the social interface index, cultural uniqueness, store diversity, crowd gathering, colour richness, the green visual rate, street pavement cleanliness, new and old building coordination, and building façade richness. In addition, some indicators also have a strong impact on the AHP and entropy weight methods.
According to the order of influence of index weights, the residents’ comprehensive evaluation of implementation effects of improving the quality of commercial streets is analysed by three types of indicators: space carrying capacity, environmental comfort, and travel safety. Space bearing capacity includes the coordination of old and new buildings, the richness of building façades, and the cleanliness of the street pavement. Environmental comfort includes cultural uniqueness and store diversity. Travel safety includes the vehicle disturbance index and proportion of street accessories. Next, we will analyse the weighting results based on the importance of the metric.
4.1. Spatial Carrying Capacity
Harmony between old and new buildings: In urban regeneration in China, it is the policy of the local government to upgrade urban communities, urban streets, etc., in order to enhance urban competitiveness and improve the urban landscape. Urban regeneration remains a government-led and important area of intervention and continues to adapt to the new challenges and opportunities of the 21st century. In this empirical analysis, Shuanggang Old Street is a district of renewal, and government intervention is an important factor affecting the renewal project, indicating that the government’s planning for urban renewal projects accelerates ecological restoration, texture remodelling, and functional improvement, and compensates for the shortcomings of public space and service facilities. The coordination of the old and new buildings can be obtained through a variety of design methods, from the perspective of the structural connection and transition design of the expansion of the new building, the separation treatment of the foundation parts of the new and old buildings, as well as the lightweight structural connection between the superstructures and the transition of the atrium space. From the perspective of the façade and material design of the expanded new building, attention should be paid to the design of many details, such as texture, scale and proportion, and colour.
Richness of the building façade: The number and composition of elements on the façade of the building, and the contrasting relationship between them, determine the visual quality and interest. Great urban architecture requires that, at every scale, from different viewing distances, the surface of the building can present a wealth of detail. There are also many highlights that can be discovered in the design of building façades, such as changing the spatial structure with dynamic façades, balancing old and new buildings through the style of façades, adding ecological elements to create green spaces, and researching materials to design high-performance façades. Therefore, the combined weight of the richness of the building’s façade reflects the satisfaction of the residents, which will have a positive impact on the improvement of street quality and vice versa.
Neatness of street pavement: The street pavement is designed to be renovated in the quality improvement work of Shuanggang Old Street, but as Shuanggang Old Street is an important commercial street in Hefei, there are more shops along the street and most of the residents are elderly people who have been living there since the 1980s; the overall quality of life of the residents is not high and therefore more domestic waste is produced. There are higher institutional requirements for the disposal of domestic waste in the streets than in Western countries. Under different systems, residents have different expectations of street surface tidiness in Hefei and in developed western countries. Urban sanitation, as an important component of fine management, should be delineated as an area of responsibility, using the requirements of fine environmental governance as a standard. Therefore, the government and the community should encourage residents to participate in street governance and subsequent renewal management, while carrying out resident activities and related educational programmes to improve the overall quality of resident participation.
4.2. Environmental Comfort
Cultural uniqueness, the comprehensive weight value of shop diversity, is greater than 0.6, indicating that cultural uniqueness and store diversity have a certain impact on the evaluation of the quality improvement of commercial streets. Commercial streets are the epitome and essence of urban commercial forms, and, in Hefei, a city where spiritual pursuit is greater than material pursuit, people are no longer limited to clothing and food, but also pursue spiritual pleasure and spiritual satisfaction. The desire for historical and cultural accumulation is particularly strong, so the integration of architectural style, landscape elements, and commercial subjects with the local characteristic cultural atmosphere should be emphasised. With the rapid development of the market economy and the advent of the Internet information age, consumers’ choice of goods is more meticulous, the common competition of different brands of similar goods is very obvious, and more international brands have also entered the perceptions of the people, thereby enhancing the shopping experience of consumers. The environment of the commercial street is one of the most important factors for the prosperity of the commercial street, and the current consumers do not only buy the goods themselves, but also the real vitality of the modern business form lies in feeling and experience. Therefore, in the design, it is important to rely on the existing historical and cultural resources of the city, or deliberately reflect the culture of a certain period in the design; the architectural form, street pieces, environmental creation, and even sales form are integrated into specific elements, reflecting the connotations of urban history and culture, so the commercial block is an important carrier of urban history and culture, and the development of commercial blocks plays an important role in protecting the characteristics of urban history and culture and continuing the urban context.
4.3. Travel Safety
The vehicle disturbance index and the percentage of street appurtenances have a significant impact on the evaluation of the effects of quality improvement of commercial streets. Most of the residents of Shuanggang Old Street are elderly, the daily travel mode is mostly walking, and there are more shops on both sides of Shuanggang Old Street. The shopping experience is easily disturbed by incoming and outgoing vehicles, so that they have a stronger sense of travel security, and the elderly are more sensitive to vehicle interference on commercial streets. Street ancillary facilities are the highest in the comprehensive weight, 0.092, which indirectly indicates the satisfaction of residents with street ancillary facilities, mainly because the streets of Shuanggang Old Street are narrow, the traffic flow is large, the speed of vehicles is slow, and they pay attention to traffic safety. However, residents’ daily travel will still be disturbed by vehicle noise, affecting the walking experience, and policies or actions should be formulated to restrict vehicles from travelling within the specified time, in order to improve the safety of street travel.
5. Conclusions
This paper investigates the evaluation of the quality enhancement effects of important commercial streets in Hefei, which have undergone certain quality enhancement renovation designs. The aim of this study is to use the AHP and entropy method to comprehensively evaluate the influencing factors of the quality enhancement effect of commercial streets. The results show that (1) travel safety and social interaction significantly affect the evaluation of the quality enhancement effect of commercial streets; (2) residents’ evaluation of the coordination of old and new buildings and the comfort of the street environment at this stage is insufficient, and the coordination and unity of urban renewal projects with surrounding buildings should be considered, as well as understanding residents’ needs for the street environment and services, and the role of local governments.
There are limitations to this study. Firstly, the study sites were not very large, resulting in an inadequate number of questionnaires. Further research could increase the choice of study sites—for example, by conducting comparative analyses of multiple study sites—to obtain more accurate findings. Secondly, although this study used a combination of AHP and entropy weighting, the results of the residents’ questionnaires were subjective and further research could include experts with expertise and experience related to specific indicator categories of the street project (e.g., material, environmental and ecological, economic, social, etc.) and could allow residents and experts to work together to calculate the AHP weights and then weight them with entropy weights to obtain more accurate data results.
Although this study is only an experiment to evaluate the effectiveness of an engineering quality improvement facility in Shuanggang Street, Hefei, a summary of the literature and a systematic approach to what works in engineering facilities paves the way for the subsequent exploration of the topic. The model proposed in this paper can help rating system developers to design a generic research framework to address the problems encountered in the implementation of sustainable road rating systems. In the future, by evaluating actual data from different cities or regions, we can provide insights into how to translate sustainability goals into concrete and feasible strategies to achieve higher quality of life for people. This is the point highlighted in this paper.