Rationality and coordination: Visualizing highway network in Sichuan,China

Highway structure is a representation of the spatial pattern of socioeconomic development and the interaction between regions, and also is a precondition for economic development (Niu and Li, 2019; Weiss et al., 2018). There was an average annual 24 percent increase in reported highway mileage in Sichuan Province in the Sichuan Statistic Yearbook (Sichuan Bureau of Statistics,1997–2017), from 1997 to 2017. The 2017 figure was 6,821 kilometers, ranking second in China. This study mapped Sichuan’s highway network on an equal per capita GDP cartogram and on an equal highway freight volumes cartogram to recognize the rationality of highway layouts and its coordination relationship with the population and economic development.

The basic data consist of three parts. (1) the Geographic Information System data of Sichuan, including the Sichuan map data and the Sichuan highway network data. The Sichuan map data were obtained from the National Fundamental Geographic Information System of China; the Sichuan highway network data were obtained from OpenStreetMap. (2) the highway freight volume data, obtained from the Department of Transportation of Sichuan Province. (3) the 2017 population and capita GDP data, obtained from the Sichuan Statistical Yearbook 2018 (Sichuan Bureau of Statistics, 2018).

The map is produced and shown in Figure 1, Figure 2, and Figure 3 as Sichuan’s highway network distribution relative to its area, per capita GDP, and highway freight volume respectively. The regions are rescaled according to their respective area, highway freight volume, and per capita GDP to produce a map with evenly distributed area density, highway freight volume density, and per capita GDP density. Then, Sichuan’s highway network is superimposed on the map in proportion.

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Figure 1.

Sichuan’s highway network on an equal area cartogram.

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Figure 2.

Sichuan’s highway network on an equal per capita GDP cartogram.

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Figure 3.

Sichuan’s highway network on an equal highway freight volumes cartogram.

As revealed by Figure 1, the geographical imbalance of highway layout in Sichuan Province is obvious. The highway is mainly distributed in the eastern plains and hilly areas, with an area of 885,000 km² (accounting for 18.2 percent of the province’s area) and the mileage of 4,500 km (accounting for 66.2 percent of the total mileage of highways), and the area density is about 5.1*10⁻² km/km². However, the area density of highway in plateau mountainous areas is only 5.8*10⁻³ km/km², almost exactly 1/9 as many the area density of plains and hills.

According to Figure 2 and Figure 3, it is apparent that there are obvious regional differences in per capita GDP and highway freight volume; however, Sichuan’s highway layout has good coordination with per capita GDP and highway freight volume. The plains and hilly area are magnified due to the high per capita GDP and highway freight volume, and the size of the mountain and plateau area is reduced. The most prominent enlargement are the districts where the prefecture-level municipal governments are located and the surrounding areas, which per capita GDP and highway freight volume amount to 5,056–20,299 US dollars and 60,472–486,334 tons respectively. The size of other districts and counties is significantly reduced due to per capita GDP and highway freight volume mainly between 1,343–5,655 US dollars and 0–64,071 tons respectively.

Overall, Sichuan’s highway layout has been well adapted to the topographical and geomorphological conditions, and the economic needs. But it also shows that the density of the highway network is still seriously inadequate in the vast mountain and plateau area. With the implementation of the Sichuan–Tibet Railway Major Project and the Sichuan Highway Network Planning (2019–2035), traffic conditions in the western mountain and plateau areas are expected to be significantly improved. This will play an important role in poverty alleviation.