Abstract: With the rapid development of the nation’s economy, China is actively improving the highway system and widening engineering to meet the increasing traffic demand. At present, there is no relevant standards and guidelines and few reference literatures for the highway widening geotechnical investigations. By collecting the reference data, this paper state-of-the-practice of the geotechnical investigations for the highway widening projects. Issues that need to be paid attention in the highway widening project geotechnical investigations, such as the utilization of the existing investigation data, reasonable distribution of the investigation workload, combination of the current and existing investigation data for the current widening plan, utilization of the “digital investigation” and “green investigation”. Some of the existing hard copies can be digitized into electronic files so that the information can be rejuvenated and integrated. 

Key words: Expressway, Widening Engineering, Engineering Geological Investigation；State-of-the-Practice