Research on the road landscape evaluation system with the emphasis on the landsc

Abstract. As the idea of the sustainable development wins support among the people, people have already realized that not only should the road have the transportation function, but we also should consider the rationality of the road construction from the multiple angles of the landscape ecology, and the visual art and so on. From the point of view of the landscape ecology, combined with the characteristics of the landscape ecology and the overall targets and requirements of the evaluation, this article constructs a three-tier system of indicators, uses the fuzzy comprehensive evaluation model based on the analytic hierarchy process to evaluate the road landscape, and makes an empirical analysis with the evaluation of the road landscape from the Luoshi Road to the East Lake Road in the Second Loop of Wuhan City as an example.

Keywords: Landscape ecology; road landscape; evaluation method; indicator system

1. Introduction

The modern traffic is developing towards the direction of the stereoscope, high speed, diversification, and networking, and at the same time, the road landscape has also undergone the fundamental changes. And the corresponding road landscape design is no longer to meet the demands of the flows of the people and the cars, but should pay more attention to the coordinated development of the environment, the economy, and the traffic. At the same time, the large-scale construction of the roads causes great damage to the environment, which has become increasingly prominent, causing a great impact to the ecological environment, the landscape resources, and the visual environment of the regions along the roads. So the road systems, economic and applicable in the aesthetics, society, and ecological environment have become the focus of the current road planning and construction. The road landscape designing and evaluation require that the roads should become a part of the natural landscape, and that the roads and the surrounding environments should match to a proper extent, and become the organic part of it.

2. The establishment of the evaluation index system

For this research project, the methods of selecting the evaluation indexes are mainly the investigation and research method and the target decomposition method, to establish the evaluation index system of the road landscape. (Fig. 2-1)

In the evaluation process, according to the characteristics of the landscape ecology and the overall objectives and requirements of the evaluation, this article constructs a three-tier system of indicators. The first tier is the final goal of the road landscape evaluation with the emphasis on the landscape ecology the overall landscape quality. And then it is decomposed into the second tier that can reflect the indexes the sub-indicator, and according to the principle, decompose again, until the single evaluation index at the bottom, and finally construct a three-tier framework of the evaluation index structure of the quality of the road landscape.

The sub-indexes of the quality of the road landscape evaluation mainly include three aspects: the quality of the ecological environment of the landscape, the quality of the functional environment of the landscape, and the quality of the visual environment of the landscape. The quality of the ecological environment of the landscape mainly reflects the ecological conditions of the road environment, including the effects of the road on the topography and the landform, the impact on the ecological environment, the influence on the natural landscape and other factors. The quality of the functional environment of the landscape mainly reflects the factors of the road itself, including the improvement of the road on the flows of the human resources and logistics, the road greening and the traffic engineering facilities. The quality of the visual environment of the landscape mainly reflects the coordination of the road and the landscape along the lines, and the visual effects of the road greening and the ancillary facilities and so on, including the landscape sensitivity, the impact on the people, the coordination of the greening and the road characteristics and the road pavement route etc.

Based on the three-tier evaluation index system, starting from the point of view of the landscape ecology, according to the characteristics of the road landscape, we select the following factors as the road landscape evaluation indexes.

3. The fuzzy comprehensive evaluation model based on the analytic hierarchy process (AHP)

The analytic hierarchy process (AHP) is the method to determine the weights of the factors with the use of the treatment of the multi-factor classification, and the basic idea is that the evaluators decompose the complex problems into the each interrelated and orderly hierarchy, so that all the hierarchies are systematic and orderly, in order to effectively analyze the problems and solve the problems. Express with the fixed quantity the relative importance of each of the two different elements in each hierarchy, and conduct the simple comparison, judgment and calculation between them, and finally calculate the weights of all the related elements. The steps are as follows:

3-1. Define the problems

By using the AHP method, first of all, have a clear understanding of the problems to be studied. Specific to the road landscape, we should comprehensively take into account the landscape ecological needs, and carry out the comprehensive evaluation of all the aspects of the road landscape vision, functions, environment, and ecology.

3-2. Construct the hierarchical structure

Based on the analysis of the problems to be studied, construct the factors into a tree hierarchy according to the system and hierarchical structure. (Fig. 3-1)

3-3. Compose the judgment matrix using the fuzzy comprehensive evaluation method

The judgment matrix is to determine the matrix elements through the multiple comparisons of the importance of the factors of this layer with a certain factor of the above layer as the evaluation criteria. According to the theory of the fuzzy comprehensive evaluation, combined with the hierarchy of the road landscape evaluation indexes, determine the judgment matrix:

3-3-1. Establish the set of the factors

The collection of each of the factors influencing the values (scores) of the assessment objects is known as the factor set, i.e.:

; Among them, each element has the fuzziness.

3-3-2. Build the set of the weights

The degree of importance of the influence of various factors on the value of the evaluation objects is not the same, so the factors should be given the corresponding weights. Set the weights , which is known as the factor weight set.

Usually, the weights should satisfy the conditions of the normalization and the non-negativity:

(3-1)

In order to make the determined weights more reasonable, then, determine the weights using the analytic hierarchy process (AHP).

Assume the influence of n factors for the comparison X={x1, x2,…, xn} on the targets Z, and determine the proportion of them in the Z. Each time, select two factors xi and xj, and use aij to express the ratio of the influence of xi and xj on Z, and obtain the judgment matrix through the multiple comparisons A=(aij)n×n. The two matrix elements represent the relative importance of the factors in the sub-indicator level to the Ai and Aj in terms of the total index A.

The judgment of the relative importance of Ai to Aj usually values from 1 ~ 9 and its reciprocal (Table 3-1)

The way to calculate the weight value of the relative importance of various elements in this layer in terms of a certain element in the above layer is to find the eigenvector of the judgment matrix. First, work out the maximum values of the judgment matrix A, and then, use:

(3-2)

Work out the corresponding feature vector W. After the standardization, W is the hierarchy weight value of the corresponding elements in the same level compared with the certain factor in the above layer.

Finally, check the consistency of the judgment matrix, and then define:

(3-3)

In this equation: CI―― the coincidence indicator

n ―― the orders of the judgment matrix

Compare the CI with the average random consistency index RI (in table 3-2), set CR=CI/RI and CR is called the random consistency ratio. When CR

Table 3-2 RI value of the judgment matrix

3-3-3. Establish the evaluation set

In the evaluation of the road landscape environment, set the evaluation set:

3-3-4. Single factor fuzzy evaluation

Conduct the evaluation from the single factor, and determine the membership degree of the evaluation objects on the elements of the evaluation set, which is called the single factor fuzzy evaluation. In general, evaluate the target, according to the I factor ui in the factor set, and the membership degree of the j element vj in the evaluation set is γij, and the results can be expressed as a fuzzy set:

(3-4)

3-3-5. The first-level fuzzy comprehensive evaluation

If the degree of importance of the factors is the same, that is, all the weights ai in the weight set are the same, at this time, as long as we add the elements of every list in the R matrix, we can respectively obtain the "scores" of all the elements in the evaluation set. If each factor weight ranges, then we need to conduct the calculation of the fuzzy matrix:

(3-5)

In this equation, the "・" is the generalized fuzzy multiplication, and usually operate by the general rules of the matrix multiplication.

3-3-6. Multilevel fuzzy comprehensive evaluation

Because the road landscape indicator system is a multi-level structure, therefore, it requires a multilevel fuzzy comprehensive evaluation. In the second-level comprehensive evaluation, the single factor evaluation matrix is as follows:

(3-6)

Then, the conclusion vector of the second-level evaluation criteria is:

(3-7)

In this equation, R二级-- The single factor judgment matrix of the second-level comprehensive evaluation;

Bi一级-- The matrix consisting of the conclusion vectors of the first-level comprehensive evaluation

Ai-- The weight vectors of the first-level evaluation

Ri一级-- The first-level single factor evaluation matrix

B二级-- The conclusion vector of the second-level comprehen sive evaluation

A二级-- The weight vectors of the second-level evaluation

bj二级-- The degree of membership of the evaluation objects evaluated according to the second-level evaluation

Similarly, the single factor evaluation matrix can be introduced of the multilevel fuzzy comprehensive evaluation above the second level, and the vector of the conclusion of the evaluation can be obtained. Usually according to the principle of the maximum membership degree, judge the final results of the evaluation of the grade of the road landscape.

4. Example verification

4-1. General situation of the items

The design of the project starts from Wuhan University of Technology in the west, to the Donghu Garden Hotel in the east along the Luoshi Road. The total length of the highway is 4.525km. As is shown in Figure (4-1), according to the characteristics of the project and the relative independence, divide the designing road sections into four engineering sections. The first section is in vertical cross section of Wuhan University of Technology, including the tunnel of the second ring line through Wuhan University of Technology. The second section is the Street Interchange Section, and the main project is the street overpass. The third section is the interchange section of the Eight One Road, and the main project is the interchange in the Eight One Road. The fourth section is the East Lake section of East Lake, mainly including the project of the second ring line through the East Lake.

4-2. Explanation of the evaluation indicators

According to the actual situations of the project and the characteristics of itself, rationally screen the evaluation indicators of the road landscape, and compose the evaluation index system shown in Table 4-1.

4-3. The establishment of the evaluation model

Based on the establishment of the factory set, and the evaluation set, combined with the weights of each indicator, we establish the statistics table of the single factor evaluation data 4-2:

By the analysis of the evaluation data of the project and consulting the experts, after concluding the single factor evaluation matrix, conduct the first-level fuzzy comprehensive evaluation. And conduct the second-level fuzzy comprehensive evaluation with the conclusion vector of the first-level evaluation criteria as the single factor evaluation matrix of the second-level fuzzy comprehensive evaluation, to obtain the conclusion vector of the second-level evaluation criterion.

Similarly, we can solve the conclusion vector of the multi-level evaluation criteria, and finally obtain the conclusion vector of the comprehensive evaluation as follows:

According to the principle of the maximum degree of membership, we think the level of the road landscape from Luoshi Road to East Lake section of the second ring in Wuhan city is "good".

The route design of the project is reasonable. Although there is a certain amount of the earthwork excavation, it is in harmony with the landscape along the route, and the landscape design involves many aspects, without too much damage to the landscape ecological system in this area, which maximize the protection of the natural landscape and the human landscape along the line.

5. Conclusion

This paper presents a set of relatively complete evaluation index system, including the quality of the ecological environment of the landscape, the quality of the functional environment of the landscape and the quality of the visual environment of the landscape, and determines their respective evaluation indexes, and gives the concrete calculation method. Finally, conduct the landscape evaluation with the road landscape from Luoshi Road to East Lake Road in the second ring of Wuhan city as an example. The landscape evaluation results show that the evaluation method described in this paper can reflect the influence of various factors on the road landscape in a certain extent, and can give the performance index to the degree of influence. But most of the indicators involved in the specific evaluation process are the qualitative indicators, which have brought difficulties to the accuracy of the measurement and evaluation of the indicators. In addition, in order to make the road landscape evaluation better guide the future landscape construction work on the road construction projects, we also need to analyze deeply and rationally the road landscape system from the perspective of the system, and then select, the more reasonable and more targeted indicators according to the features and differences of the different types of the roads (roads, city streets, highways and so on), and collect more data in the practical work for the examination and perfection.

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