5.1. The Spatial and Temporal Characteristics of the Comprehensive Development Level of Multimodal Transportation
We calculated the comprehensive evaluation scores for the development levels of buses, rail transit, and taxis in 36 Chinese cities from 2016 to 2020, as well as the comprehensive evaluation scores for the overall development level of multimodal transportation, as shown in
Figure 1.
On the whole, the comprehensive development level of urban multimodal transportation in China has shown an obvious upward trend in the five years from 2016 to 2020, with an average annual growth rate of about 7.36%. This indicates that the development of such transportation in China has improved well in recent years. The infrastructure of buses, rail transit, and taxis has gradually been improved, and the operational capacity has been greatly improved, satisfying the different travel demands and preferences of residents.
Specifically, the comprehensive evaluation score for buses was the highest, followed by that for rail transit, and then that for taxis, from 2016 to 2020. In 2020, the urban bus passenger capacity was 1.2 times that of rail transit, the taxi passenger capacity was 3.2 times that of rail transit, and the bus operating line length was 52 times that of rail transit. To some extent, this shows that buses, as a mature public transport mode, have been relatively better in terms of operation management, operation technology, infrastructure planning and construction, and other aspects, compared with rail transit and taxis. Therefore, buses show a relatively good level of development. However, in terms of growth rate, that of China's urban bus development level was only 10.6%. Looking at rail transit development, it required more infrastructure in the urban environment, and the rail transit construction and development cycle is relatively long, consuming manpower, material resources, and finances. By 2020, 32 out of 36 major cities in China had rail transit in operation. Some cities started late and still need time to develop their rail transit. However, the growth in rail transit development was fast over 2016–2020, up to 30%. To some extent, this shows that rail transit, as an emerging, green, and high-capacity public transport mode, has won the favor of more travelers. Compared with 2016, the number of rail transit stations and passenger capacity had increased by 88.2% and 8.4%, respectively, by 2020. At the same time, the number of cities with rail transit in operation has gradually increased, and the coverage of the rail transit infrastructure has also increased, allowing it to carry more passengers, and showing a good trend of development. In 2020, the taxi passenger capacity was only 37% of the rail transit passenger capacity. This is significantly lower, and there is still a big gap in the overall development level of taxis compared with buses and rail transit. However, the overall taxi development level grew rapidly from 2016 to 2020, by 21.2%. Therefore, the smooth development of the bus system and the positive development of the rail transit system and taxi system will play a crucial role in improving the development of urban multimodal transportation in China.
Figure 2 shows the comprehensive development level of buses in 36 cities in China from 2016 to 2020. On the whole, Guangzhou, Chongqing, Beijing, Shanghai, and Harbin had the highest level of bus development from 2016 to 2020. In November 2018, under guidance and support from the government, Guangzhou Bus Group completed the electrification of its buses, a green development, further improving the level of green travel in response to the Outline of Building a Transport Power. In 2020, the area of bus stations in Guangzhou was 4.1 times that in 2016, and the number of new-energy vehicles was 3.4 times that in 2016. The coverage of bus infrastructure in Guangzhou was further expanded. At the same time, in 2020, the length of the BRT operation line, the number of BRT operating vehicles, the number of new-energy operating vehicles, and other indexes put Guangzhou at the forefront of the 36 cities. In 2020, the number of business operators in Chongqing put it first among the 36 cities, and the operating line length and number of operating lines were 2.5 times and 2.4 times the average level, showing a good level of bus infrastructure construction. Beijing ranked first among the 36 cities in terms of the length of the bus lanes and passenger capacity. The number of new-energy operating vehicles in Shanghai and the operating mileage put it at the forefront of the 36 cities. For cities with a better development level of buses, this is the key factor for maintaining a good level of bus infrastructure to ensure its stable development. Meanwhile, Nanchang, Taiyuan, Lhasa, Shijiazhuang, and Haikou were the five lowest-ranked cities in terms of bus development from 2016 to 2020, with Haikou the lowest. By the end of 2020, Haikou had not opened any BRT routes or put BRT vehicles into use, and its numbers of new-energy bus vehicles and bus lanes were only 10.1% and 2.1% of Guangzhou’s. A series of infrastructure construction problems, such as with bus resource allocation, route length planning, and route operation, led to the low development level of Haikou’s bus system. Shijiazhuang, Lhasa, and Taiyuan did not plan to open BRT routes or put BRT vehicles into use in 2020. In 2020, the bus mileage and passenger capacity in Lhasa were only 8.3% and 12% of the average levels, respectively. These cities having a low level of bus development should focus on a “bus priority” development strategy, optimize the layout of local bus routes, pay attention to the delivery and use of new-energy vehicles and BRT vehicles, and further improve the development level of their urban bus systems.
In terms of the growth rate of bus development in the 36 cities, the cities with the fastest average growth rates were Lhasa, Nanchang, and Zhengzhou, of which Lhasa had the highest at 29%. In 2020, operating line length, the number of operating lines, and the number of new-energy operating vehicles in Lhasa were 2.7 times, 2 times, and 3 times those in 2016, respectively. The operating mileage increased by 8.8% compared with 2016. Although the average growth rate of Lhasa's bus development was fast, the development level was still low and there is still a lot of space for development. It will be necessary to pay attention to the planning and construction of bus lines and stations, and to open BRT vehicles and routes. The growth rate of bus development in Zhengzhou was 14.6%. In 2018, the operating line length of its BRT was 8.9 times that in 2017, representing breakthrough growth. For cities with rapid growth in bus development, the key to maintaining steady growth is to stabilize the index factors that promote development. Haikou, Wuhan, and Nanning had the slowest average growth rates, with Haikou having the lowest at -7.8%, and also the lowest development level. For example, in 2020, the number of operating lines, length of bus lanes, and number of bus vehicles in Haikou decreased by 2.7%, 61.1%, and 7.8%, respectively, compared to in 2019. Haikou’s bus passenger capacity has been in continuous decline since 2017. Compared with 2016, by 2020 its bus passenger capacity had decreased by 58.3%. The relevant departments will need to improve the local bus infrastructure construction, looking at the aspects of bus route planning, layout, and vehicles.
The growth rates of the comprehensive evaluation scores for bus development fluctuated greatly in Tianjin and Ningbo between 2016 and 2020. In 2020, the bus operating mileage and passenger capacity in Tianjin decreased by 12.5% and 43.7%, respectively, compared with 2019, while its operating line length increased by 6.3% compared with 2019. For the cities where the growth rates of bus development fluctuate greatly, the relevant departments should determine the factors restricting bus development and make some adjustments accordingly. The growth rate of bus development was relatively stable in Dalian, Lanzhou, and several others. The comprehensive evaluation score for Lanzhou's bus development level maintained steady growth from 2016 to 2020. Its operating line length in 2020 was 1.2 times that in 2019, and 1.5 times that in 2018. For cities with relatively stable growth in bus development, the relevant departments will need to maintain this stable growth, by continuing to optimize and improve the bus infrastructure, and operating level.
When it comes to urban rail transit, the duration of operations is not uniform across the cities studied. In order to make a clearer comparison of the variation in the comprehensive development of urban rail transit from 2016 to 2020, only 24 of the cities were selected as the research objects, all of which operated rail transit from 2016 to 2020.
Figure 3 shows the changes in the comprehensive development of rail transit in these 24 Chinese cities from 2016 to 2020. On the whole, Beijing, Shanghai, Guangzhou, and Shenzhen had a good level of rail transit development during 2016–2020. Of these, Beijing had the best level with long operating times, perfect rail transit infrastructure, a mature operation mode and management experience, and an effective policy support environment. It was clearly required in the Beijing City Master Plan (2016–2035) [
63] that the comprehensive benefits of rail transit and transportation hubs should be fully utilized, and the integrated planning of rail transit stations and use of the surrounding land should be strengthened. By the end of 2020, Beijing’s rail transit operating mileage was ahead of other cities, with the number of stations and transfer stations 3.5 times and 5.1 times the average levels, respectively. In 2020, Shanghai’s rail transit ranked first in terms of operating line length, number of stations, number of attached vehicles, passenger capacity, passenger-kilometers, and some other indexes, with excellent overall rail transit infrastructure construction. In the developing cities of the Guangdong-Hong Kong-Macao Greater Bay Area, Guangzhou and Shenzhen are actively building an integrated public transport system with urban rail transit at its core, further optimizing the structure of urban transport and alleviating urban congestion. Among these cities, Guangzhou surpassed Beijing in rail transit passenger capacity in 2020, at 5.04 times the average level. However, overall, there was still a large gap between its rail transit infrastructure construction and Beijing’s. Nanchang, Hefei, Harbin, and Fuzhou all had a relatively poor development level of rail transit from 2016 to 2020. Among them, Fuzhou had the lowest level. By the end of 2020, the length of rail transit operating lines, number of assigned vehicles, and operating mileage in Fuzhou were at only 28.5%, 27.1%, and 24.4% of the average levels, respectively. In Harbin, the number of attached vehicles and operating mileage were only 14.2% and 13.3%, respectively, of the average levels in 2020. Hefei only opened rail transit operations in 2016. For cities with a low development level of rail transit, the local departments should continue to focus on the layout and optimization of infrastructure, such as the planning of the opening of rail transit operating lines, route construction, stations, and vehicle configuration, so as to attract more passengers and meet the daily travel needs of city residents.
From the perspective of the growth rate of rail transit development in the 24 cities, Qingdao, Nanning, and Hefei had the highest average growth rates from 2016 to 2020. Qingdao had the highest at 30.3%. In 2017, the operating mileage and inbound volume in Qingdao were 2.9 times and 5.8 times those in 2016, respectively, and the number of attached vehicles increased by 75.5% compared with 2016. It is necessary to maintain a good infrastructure and operating level. Nanning and Hefei both had newly opened tracks in 2016; thus, they started late but grew fast. In 2020, the operating line length, operating mileage, and passenger capacity in Nanning were 3.4 times, 22.3 times, and 30.5 times the figures in 2016, respectively. In 2020, the operating line length and number of attached vehicles in Hefei were 4.6 times and 5.5 times, respectively, those in 2016. However, the comprehensive development levels of the rail transit in Hefei and Nanning were still relatively low. Therefore, the relevant local departments still need to pay close attention to the gap between their rail transit infrastructure construction levels and those of other cities, so as to optimize and improve their infrastructure as much as possible. Furthermore, the average growth rate of the rail transit development level was relatively low in Ningbo, Beijing, and Dalian from 2016 to 2020. Among these, Ningbo had the lowest rate of −5.1%. The operating line length, number of attached vehicles, and number of operating lines in Ningbo did not change from 2016 to 2018, and the overall growth rate was poor. Due to the impact of COVID-19, the inbound volume, passenger capacity, and daily passenger capacity in Beijing in 2020 decreased by 42.03%, 42.02%, and 42.3%, respectively, compared with 2019, but the overall development trend for Beijing’s rail transit was positive.
Figure 4 shows the comprehensive development level of taxis in the 36 cities in China from 2016 to 2020. On the whole, Beijing, Changchun, Harbin, Shenzhen, and Shanghai had good levels of development in terms of taxis from 2016 to 2020. Among them, Beijing taxis showed the highest level of development. In 2020, the number of operating vehicles and gasoline vehicles in Beijing led the country, and the number of taxis per 10,000 people was 1.7 times the average level. The overall development trend of taxis was positive. The number of taxis per 10,000 people in Changchun was 1.7 times the average level, and in terms of the taxi mileage utilization rate, it ranked first among the 36 cities. The number of ethanol gasoline vehicles, taxi passenger capacity, and taxi mileage utilization rate in Harbin were all good, with taxi passenger capacity 2.01 times the average level. The number of battery-powered electric vehicles in Shenzhen was 8.4 times the average, and the proportion of new-energy vehicles was high in 2020. The operating mileage and passenger capacity in Shanghai were 2.9 times and 2.04 times the average levels, respectively. It is necessary for taxi development to maintain a high level of basic operating vehicles. Cities with a relatively weak development level for taxis included Nanchang, Haikou, Lhasa, Hohhot, and Ningbo. In 2020, the number of taxis operating in Ningbo increased by only 3.6%, while the number of passenger miles decreased by 91.6% compared with 2016. The number of battery-powered electric vehicles in Hohhot was zero in 2020. Thus, development and investment in new-energy taxis will help Hohhot to improve its development level. In 2020, the numbers of taxis operating in Lhasa and Haikou were only 7.1% and 14.9% of the average levels, respectively. For cities with low development of taxis, the local governments should focus on updating and increasing vehicles or giving priority to the use of new-energy vehicles, so as to promote the improvement in the local taxi industry.
Looking at the average growth rates of the taxi development in the 36 cities, those with the fastest growth rates were Zhengzhou, Nanning, Kunming, Chengdu, and Chongqing. In 2020, the number of battery-powered electric vehicles in Zhengzhou achieved a large coverage area, despite the number of such vehicles in 2016 having been zero, and the total number of vehicles carrying passengers was 4.8 times that in 2016. Meanwhile, Zhengzhou introduced a subsidy policy for the renewal of battery-powered electric vehicles, greatly promoting the proportion of such taxis. Compared with 2016, the total number of vehicles carrying passengers in Nanning in 2020 was 4.5 times that in 2016. The number of battery-powered electric vehicles and the total number of vehicles carrying passengers in Kunming in 2020 were 23.08 times and 4.9 times those in 2016, respectively. Cities with slower growth rates were Lhasa, Taiyuan, Tianjin, Urumqi, and Haikou. Lhasa had the lowest rate of -11.7%. Due to the severe impact of COVID-19, the number of taxis operating in Lhasa in 2020 decreased by 39.5% compared with 2016. The overall development level of Lhasa’s taxis was poor, and the proportion of new-energy taxis was very low. The transportation department there needs to expand the share of new-energy vehicles based on specific local traffic conditions. The number of taxis operating in Taiyuan did not change from 2017 to 2020, and taxi passenger mileage in 2020 decreased by 85.6% compared with that in 2016. During 2016-2020, the number of battery-powered electric vehicles in Tianjin did not expand, and the electrification of taxis there was extremely low. Passenger capacity and passenger mileage in 2020 decreased by 77.2% and 97%, respectively, compared with 2016. For cities where the average growth rate of taxi development is relatively slow, it is necessary to prioritize the use of new-energy vehicles, to add or update vehicles operating as taxis, and to improve taxi service facilities.
5.2. Coupling Coordination Relationship of Multimodal Transportation
The results for the urban coupling coordination degrees for B-R-T, B-T, B-R, and R-T are shown in the
Appendix A (
Table A1,
Table A2,
Table A3 and
Table A4).
Figure 5 shows the coupling coordination degree for B-R-T and its average growth rate for 31 of the major cities in China from 2016 to 2020. Just 19.35% of cities were in the balanced development stage, while 80.65% were in the unbalanced development stage. On the whole, there is uncoordinated development between buses, rail transit, and taxis in the major cities of China.
Beijing, Shanghai, Guangzhou, Shenzhen, Chongqing, Chengdu, and Changchun were all in the first quadrant. During 2016–2020, the coupling coordination of B-R-T in Shenzhen, Guangzhou, Shanghai, and Beijing fell into favorably balanced development. Relying on a favorable policy support environment, Shenzhen, Guangzhou, Shanghai, and Beijing implemented the policy of “giving priority to the development of public transport” [
22]. They were at the forefront of the country in terms of buses, rail transit vehicle configuration, line number development, and other aspects, and optimized the delivery and use of new-energy taxis. Moreover, they performed well in terms of bus, rail transit and taxi operating mileage, passenger capacity, and other aspects, thus achieving good coordinated development of their public transport. For example, the bus operating line length, rail transit operating line length, and number of taxis in Shenzhen in 2020 were 1.99 times, 2.06 times, and 1.50 times the average levels, respectively. However, the coupling coordination relationships among B-R-T in Chongqing, Chengdu, and Changchun were all at the level of barely balanced development. The average growth rate of the coupling coordination degree of B-R-T in Chengdu was high, at 7.98%. Chongqing, Chengdu, and Changchun still need to improve their construction of public transport infrastructure and expand their public transport operations so as to enhance and develop this coupling coordination relationship.
The proportion of cities in the second quadrant was 61.29%. The coupling coordination degree of B-R-T in these cities was in the stage of unbalanced development. However, their average growth rates were greater than zero. Among them, the average growth rates of the coupling coordination degree of B-R-T in Zhengzhou, Qingdao, and Xiamen were 7.94%, 7.59%, and 5.14%, respectively. The average growth rates of the coupling coordination degree of B-R-T in Dalian, Nanjing, and Ningbo were 2.12%, 1.28%, and 0.33% respectively. There is still room for improvement in the public transport infrastructure index and the operating index.
Wuhan, Tianjin, Harbin, Hohhot, and Urumqi were in the third quadrant, where the coupling coordination relationship of B-R-T was in the stage of balanced development, and the average growth rate was less than 0. Because of the impact of COVID-19, the coupling coordination score for B-R-T in Wuhan decreased in 2020. Due to the lagging development level of taxis in Tianjin, the coupling coordination relationship of B-R-T was poor. Hohhot and Urumqi were slow in their development due to the late opening of rail transit transportation in those cities, which affected the coordinated development of public transportation. Local transportation departments should pay attention to these shortcomings in the development of public transportation in these cities.
Figure 6 shows the mean and the average growth rate of the coupling coordination degree of B-T in the 36 cities from 2016 to 2020. On the whole, this relationship was inferior in the 36 major cities, with 77.8% of the cities showing unbalanced development. Furthermore, the relationship was unevenly developed in each region. Chongqing, Guangzhou, Beijing, Shanghai, Shenzhen, Changchun, and Lanzhou were in the first quadrant, with coupling coordination relationships for B-T higher than the average level. Among them, Chongqing, Guangzhou, Beijing, and Shanghai showed favorably balanced development. The average growth rate of the coupling coordination of B-T in Chongqing was the highest, at 4.96%. This better coordination relationship may be closely related to its mature policy support environment. For example, in the Outline of Chongqing’s Comprehensive Three-dimensional Transportation Network Planning (2021-2035) [
64], it was proposed that, by 2035, Chongqing should form a “123 travel traffic circle” (1 means one hour traffic circle, 2 means two hours of free travel within the city area, and 3 means three hours of coverage of major cities in China), to build a strong traffic situation in the city. In Beijing, Shanghai, and Guangzhou, the bus operating line length, operating lines, station facilities, and other construction levels were all acceptable. At the same time, new-energy taxis proliferated. Beijing, Shanghai, and Guangzhou were leading the way in terms of bus and taxi passenger capacity and mileage.
There were more cities in the second and third quadrants, accounting for 77.7% of the total, and here the coupling coordination degree of B-T was in the stage of unbalanced development. However, for the cities in the second quadrant, the average growth rate of the coupling coordination degree of B-T was greater than 0. This indicated an upward trend year by year. For example, Zhengzhou and Chengdu had changed from slightly balanced development to barely balanced development, showing a trend of continuous positive development. The average growth rates of the coupling coordination degree of B-T in Zhengzhou and Chengdu were 6.98% and 6.73%, respectively. This was mainly due to their response to the policy of “priority development of urban public transport”, in which they increased the construction of public transport stations and supporting facilities, such that the development level of buses was growing at a faster rate. In Nanning and Hohhot, the average growth rates of the coupling coordination degree of B-T were also relatively low, at 0.53% and 0.56%, respectively. For the cities in the third quadrant, the average growth rate of the coupling coordination degree of B-T was less than 0. Among these cities, Wuhan was an important core city hit by the COVID-19 epidemic in 2020, which seriously affected the growth of indicators such as bus passenger capacity, operating mileage, and average annual operating mileage. Compared with 2019, the passenger capacity and operating mileage of buses decreased by 58.7% and 40.4%, respectively. At the same time, the passenger capacity and operating mileage of Wuhan taxis decreased by 39.4% and 34%, respectively, compared with 2019, leading to the uncoordinated development of buses and taxis.
Harbin was in the fourth quadrant, with a coupling coordination relationship of B-T of barely balanced development from 2016 to 2020. Harbin had good performance in terms of the number of bus operating lines, bus passenger capacity, taxi passenger capacity, taxi mileage utilization rate, and other indicators. Simultaneously, it had a good resource endowment and initially formed a transportation network in the urban circle. However, the average growth rate of the coupling coordination degree of B-T in Harbin was less than 0, at −0.65%. Similarly, the bus mileage and passenger volume decreased by 22.5% and 54.3%, respectively, compared with 2019, due to the impact of COVID-19 in 2020, and the development level of buses showed a downward trend, further affecting the coordinated development between buses and taxis.
As of the end of 2020, Haikou, Lhasa, Xining, and Yinchuan had not yet put rail transit into operation, and Taiyuan only did so in 2020. Thus, there is no growth rate data for these cities. Therefore,
Figure 7 shows the means and average growth rates of the coupling coordination degrees of B-R in 31 cities in China during 2016–2020. Generally, 77.4% of these cities showed balanced development, while 22.6% showed unbalanced development.
Shanghai, Guangzhou, Chongqing, Shenzhen, Xi'an, Nanjing, and Chengdu were in the first quadrant. In terms of the coupling coordination relationship of B-R, Shanghai, Guangzhou, Chongqing, and Shenzhen showed favorably balanced development. Xi’an, Nanjing, and Chengdu showed barely balanced development. For example, in 2020, the lengths of the bus operating lines and rail transit operating lines in Chengdu were 2.13 times and 6.18 times those in 2016, respectively. In addition, Shanghai, Guangzhou, Chongqing, and Shenzhen had good economic endowments and advantages in terms of the allocation of resources to, construction of infrastructure for, and operation of urban bus and rail transit, and so the coordinated development of B-R was in a good state. There were more cities in the second quadrant, accounting for 54.8% of all cities. Here the coupling coordination degree of B-R was in the stage of unbalanced development. Shijiazhuang, Xiamen, and Guiyang began rail transit operations in 2017, and Lanzhou in 2019. This relatively short time of operation meant that the infrastructure construction was not perfect, and the development level of rail transit was poor, resulting in a state of unbalanced development between buses and rail transit. However, the average growth rate of the coupling coordination degree of B-R in these cities was greater than 0, and the coordination relationship of B-R continued to develop in a good direction. For example, the average growth rates of the coupling coordination degree of B-R in Qingdao, Zhengzhou, and Hefei were high from 2016 to 2020, at 8.57%, 7.41%, and 6.39%, respectively. The coordinated development of B-R showed an obvious upward trend. Among these, the coordination relationship of B-R in Zhengzhou presented the following characteristics: moderately unbalanced development in 2016, slightly unbalanced development during 2017-2019, and barely balanced development in 2020.
Jinan, Ningbo, Harbin, Urumqi, and Hohhot were in the third quadrant. The coupling coordination of B-R showed unbalanced development in these cities, and their average growth rates of coupling coordination were less than zero. Since Urumqi, Jinan, and Hohhot had only opened rail transit operations in 2018 and 2019, respectively, there were still some deficiencies in construction in terms of rail line length and vehicle configuration. Wuhan and Beijing were in the fourth quadrant, with barely balanced development and favorably balanced development in their B-R coupling coordination, respectively. Compared with 2016, the buses’ operating line length and rail transit’s operating line length in Wuhan had increased by 70.09% and by 2.15 times, respectively, by 2020. In 2020, Beijing ranked first among the 36 cities in terms of bus lane length and passenger capacity, and its number of rail transit stations and number of transfer stations were 3.5 times and 5.1 times the average level, respectively, showing a good level of bus and rail transit infrastructure construction. However, the average growth rates of the coupling coordination of B-R in Wuhan and Beijing were less than 0. One of the reasons for this was that the number of rail transit inbound stops and the passenger traffic in Wuhan and Beijing had decreased by 49.27% and 49.27%, and 42.03% and 42.02%, respectively, in 2020 compared with 2019.
Figure 8 shows the means and average growth rates of the coupling coordination degrees of R-T in 31 major cities in China from 2016 to 2020. Overall, 77.42% of the cities showed unbalanced development of R-T, reflecting a poor condition.
Shanghai, Guangzhou, Shenzhen, Chongqing, Wuhan, and Changchun were in the first quadrant, showing balanced development, and an average growth rate in the coupling coordination degree greater than 0. The coupling coordination relationship of R-T in Shanghai, Guangzhou, and Shenzhen was in the stage of favorably balanced development from 2016 to 2020. These cities had good economic and resource endowments, advantages, and good performance in terms of rail transit infrastructure construction, rail transit operations, the launch and use of taxi vehicles, taxi operations, and other aspects. For example, Shanghai ranked first among the cities in terms of the rail transit lines in operation, number of stations, number of assigned vehicles, passenger capacity, passenger-kilometers, and other indicators in 2020. Moreover, the mileage and passenger capacity of taxis in Shanghai were 2.9 times and 2.04 times the average levels, respectively. The coupling coordination relationships of R-T in Wuhan, Chongqing, and Changchun showed barely balanced development from 2016 to 2020. Among them, the average growth rate of the coupling coordination degree of R-T in Changchun was high, at 5.59%. The relationship changed from slightly unbalanced development in 2016 to barely balanced development from 2017 to 2020, showing an obvious trend of improvement.
There were 64.52% cities in the second quadrant. These cities were in the stage of unbalanced development. Specifically, Guiyang opened its rail transit service in 2018, and the overall infrastructure and operating level were poor. Moreover, the number of battery-powered electric taxis in Guiyang was 0 in 2020, and investment in new-energy vehicles was less. These are key factors affecting the coordinated development of R-T. However, in the second quadrant, the average growth rate of the coupling coordination degree of R-T was greater than 0. Among the cities in that quadrant, Hohhot, Qingdao, and Nanning had higher average growth rates of the coupling coordination degree of R-T, at 13.30%, 10.83%, and 10.71%, respectively. The average growth rates of the coupling coordination degree of R-T in Harbin, Dalian, and Nanjing were slightly greater than 0, but still indicated relatively slow growth. In the third quadrant, the coupling coordination relationship of R-T was in the stage of unbalanced development and the average growth rate was less than 0. Due to the low level of overall development of rail transit in Urumqi and Lanzhou, which only opened in 2018 and 2019, respectively, the development of local rail transit and taxis was not coordinated.
Finally, Beijing was in the fourth quadrant, with a coupling coordination relationship of R-T implying favorably balanced development from 2016 to 2020. In 2020, the rail transit operating line length in Beijing was 1.39 times that in 2016, and the number of taxis per 10,000 people in the city was 1.7 times the average level. The overall development trend of R-T was fine. However, the average growth rate in the coupling coordination degree of R-T in Beijing was less than 0. This was due to the impact of COVID-19, which meant that the comprehensive score for Beijing's rail transit development level in 2020 had decreased by 9.92% compared with that in 2019, mainly due to the rail transit operating indicators. Relevant departments should focus on the impact of emergencies on transport operations.