How Much Will the Sichuan–Tibet Railway Improve the Accessibility of Tibet, China: A Comparative Study by Multiple Scenarios

The accessibility improvement effect of transportation trunk lines can provide a reference for further optimizing regional transportation. Focusing on the different construction stages of the Sichuan–Tibet Railway (STR), this study determined the weighted average travel time and calculated both the internal and external accessibility of 74 counties in Tibet under scenarios where the STR is not yet operational, partially operational, and fully operational. The results indicate the following: (1) After the full operation of the STR, internal transportation accessibility improved by 45%, with the average travel time reduced by approximately 4 h, showing a significant time-space convergence effect; (2) In terms of external transportation, the full operation of the STR will significantly shorten the inter-provincial travel time of all counties, with the average external travel time reduced by almost 50%, from an average of 45 h to 23 h; (3) The accessibility response of different counties to the operation of the railway exhibits clear spatial differences. The internal accessibility of the counties along the railway line improved by 50–80%, while the improvement rate of counties that are not close to the STR is between 10% and 50%; (4) Although the accessibility improvement effect brought by the construction of the STR is significant, there is still a characteristic of spatial non-equilibrium. Accompanying the operation of the STR, a further eastward-oriented accessibility advantage area has emerged based on the original accessibility advantage areas centered around Lhasa. However, the improvement effect for northwestern counties with accessibility disadvantages remaining very limited. Therefore, more plans for new transportation trunk lines such as the Xinjiang–Tibet Railway are needed, to comprehensively improve the relatively poor and uneven accessibility pattern of Tibet, as well as contribute to the shared well-being of the people and the coordinated development between regions.