A key transportation project in China, the Sichuan Lexi Expressway serves as an important pathway to alleviate poverty and increase ecological tourism, driving local economic development. With a total length of 151.8 km and a connecting line of 40 km, this megaproject runs through four counties and will connect to the planned expressway from Xichang to Zhaotong. Contractor Sichuan Highway Planning, Survey, Design and Research Institute Ltd was engaged to build the four-lane highway with a design speed of 80 km/hr within a five-year period.

To complete the job, however, Sichuan Highway had to overcome the project’s complicated topography and geology. Over 80% of the roadway length consisted of bridges and tunnels. In fact, the project covered 746.68 ha, with 137 bridges (42,773 m), 41 tunnels (84,006.5 m), six diverging interchanges, 71 culverts and pathways, four overpasses and aqueducts, and nine ramp toll stations. Furthermore, the project would run through ‘the gene bank of subtropical plants,’ which include nature preserves and tree farms with rare and protected plants. The local climate is unstable, with about 270 rainy days in a year and up to three months of precipitation in the winter, making construction, transportation, and safe operation difficult.

Searching for advanced method

Facing engineering and technical challenges, Sichuan Highway knew that traditional design and construction methods could not accommodate the project. A 40-km section running through uninhabited land had no access roads, electricity supply, or communication facilities. “People had to sleep outside in cold or heat, walk through uninhabited mountains and dense forests, and climb deep trenches and gullies filled with bogs,” said Jixing Dong, BIM engineer at Sichuan Highway Planning, Survey, Design and Research Institute.

Additionally, the team comprised over 1,500 employees in varied disciplines, including over 40 experts that range from national and provincial engineering design masters and members working for the state’s council. These disciplines needed to contribute to and communicate on this already complex project.

Therefore, Sichuan Highway sought BIM and digital twin software that had a strong carrying capacity, wide discipline applicability and unified data format, and support secondary development to meet the above application requirements. The company also wanted the application to help improve design quality and timeliness of later-stage service, raise professional and technical standards, and provide digital operation and maintenance to ensure standardised workflows and high data quality.

Improving collaboration with BIM

Sichuan Highway conducted an in-depth analysis of several software products, including those from Autodesk, Catia, Weidi BIM, Hongye BIM, and Bentley Systems. The company ultimately chose Bentley applications and, after reviewing all available options, chose the open modelling applications to establish a connected data environment, integrating and streamlining design and construction processes.

“For the Lexi Expressway project, a 151.8-km highway digital twin model was created based on Bentley [applications], which provided high-quality engineering data to all parties involved in the project; improved the level of project management, design and construction; and produced good economic benefits and social benefits,” said Qiao Ke, director of BIM centre at Sichuan Highway Planning, Survey, Design and Research Institute.

The company began by using ContextCapture to collect data and develop a reality model. Because the topographic data of the project was from complex sources and in multiple formats, the company used Bentley applications to standardise multi-source surveying and mapping data. With Bentley’s OpenBridge and OpenRoads applications, Sichuan Highway developed models for all aspects of the project, including roads, tunnels, intersections, and traffic engineering. Bentley’s MicroStation was also used to ensure that all data was in the same format, guaranteeing first-class BIM data quality.

The applications’ automated features streamlined development, making it easy for everyone on the project to efficiently collaborate. Moreover, these models can be updated in real time for use during future operations and maintenance.

Greater work efficiency

By using Bentley’s collaborative BIM and digital twin software, Sichuan Highway developed models for 234 bridges, 42 tunnels, 82 culverts, 33 relocated roads and ditches, and 36 spoil grounds. The company efficiently manages over 500,000 components and 5.73 million attributes.

Sichuan Highway expects that using the applications will reduce project costs by CNY 20 million to CNY 30 million, improving data integration, standardisation, and design accuracy; identifying more than 1,000 errors; and shortening the early stages of construction.

On track to be completed in July 2025, the Sichuan Lexi Expressway project will connect areas for improved economic development. The roadway plays an important role in the Sichuan’s network, serving as an important pathway for poverty alleviation and ecological tourism. Once operational, it will effectively drive local economic development and create many local jobs.

Image: Sichuan Highway Planning, Survey, Design and Research Institute Ltd / Sichuan Lexi Expressway Co Ltd