On 27 May 2020, under the sky with light rain, at the construction site of the Panzhihua-Dali highway general section, white smoke was emitted from the asphalt pavement from time to time, and the rumbling unmanned machinery fleet came from a distance: a large intelligent paver leading four unmanned road rollers was processing the combined road construction. As the world's first unmanned roller machinery fleet highway construction, it will continue until it is accomplished in September of 2020.

Pan-Da highway the world's first application of unmanned machinery fleet construction

The intelligent brain of this complete unmanned driving system was developed by the underground space development and utilization team and the intelligent construction team of Tsinghua University, cooperated with Xugong Group (providing vehicles and bottom control interface), Sichuan Road&Bridge Group (providing test conditions), after nearly two years of testing and and measuring. Having overcome many difficulties caused by the epidemic, the joint team completed the project on schedule and the unmanned road roller and the machinery fleet cooperative construction system finally meets the requirements of highway construction standardization.

Tsinghua University team

Pan-Da highway is an important channel for Sichuan to strengthen its ties with Southwest and ASEAN, with bridges and tunnels accounting for more than 81%. The requirement of smoothness for pavement buildings is high. It is difficult for traditional manual operations to meet the requirements of construction standardization. During the process of research and development, the cooperative team paid much special attention to reducing the safety accident rate of special road construction, and decreasing the damage of toxic gases emitted by the asphalt concrete during heating to the human body, and cooperatively researched and developed the unmanned roller machinery fleet that are suitable for the of highway construction.

Unmanned machinery fleet in construction process

The road roller collects the surrounding environment information through the GPS positioning system, microwave communication, millimeter wave radar and other sensor equipment installed on the vehicle, plans the optimal operation path according to the environmental parameters, and independently rolls the operation, and accomplishes the multi-machine unmanned rolling press collaborative work. The application of this technology has successfully made it possible for the unmanned roller to operate under complex working conditions. The construction track can be accurately controlled at 2 to 3 cm, which greatly improves the construction quality and largely reduces the operation cost.

Construction safety is the primary concern associated with the unmanned machinery fleet. Unmanned roller compactors are equipped with multi-level safety precautions to monitor construction conditions on site in real time to achieve automatic warning, emergency stop, automatic entry and exit, and automatic obstacle avoidance, etc., to provide safety protection and escort for road construction.

With the advent of the 5G era, intelligent, unmanned, and standardization of mechanical construction has become an industrial development trend. Intelligent construction aims to make full use of intelligent technology and intelligent systems to raise the level of intelligence in the construction process, reduce the dependence on people, achieve the purpose of safe construction, and improve the cost-effectiveness and reliability of construction. The research team of underground space and intelligent construction of Tsinghua University has carried out many years of research on basic theories, optimization algorithms, key technologies, system integration and other aspects of unmanned driving. The dam intelligent construction technology applied in the Qianping core-wall earth dam in Henan, the Sanhekou RCC Arch Dam and the Huangjinxia RCC gravity dam of Yinhanjiwei project has achieved a breakthrough and successful application.

This research result is a pioneering initiative to deepen cooperation in production, learning, research and application, and to fully enter the field of unmanned asphalt pavement construction. The successful application of the unmanned highway construction machinery fleet has promoted the industrialization of unmanned technology and accelerated the integrated development of smart transportation construction.