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Breaking Depth Records: XGRIDS' Lixel L2 Revolutionizes 3D Scanning for the World’s Longest Undersea Highway Tunnel

Case Studies4 min read

Mobile scanning system changes infrastructure digital construction.

Project Background: The World's Longest Undersea Tunnel

The Jiaozhou Bay Second Undersea Highway Tunnel is set to become the world’s longest underwater highway tunnel, stretching 17.48 kilometers, including 9.95 kilometers of seabed excavation. With such a massive scale and extreme geological complexity, achieving precise excavation and real-time monitoring is critical to ensure construction accuracy, efficiency, and safety.

To meet these challenges, our partner in collaboration with Southwest Jiaotong University and Southwest China Railway Research Institute, deployed XGRIDS' Lixel L2 handheld scanner to rapidly and accurately scan the tunnel and get point cloud data. The results allowed for on-site over-excavation measurements, reducing errors and improving construction efficiency.

Satellite map of the Jiaozhou Bay undersea tunnel route marking the drill-and-blast and shield tunnel sections
Satellite map of the Jiaozhou Bay undersea tunnel route marking the drill-and-blast and shield tunnel sections
3D terrain view tracing the undersea highway tunnel alignment across the bay
3D terrain view tracing the undersea highway tunnel alignment across the bay

Client Overview

Client: Baisui, Southwest Jiaotong University & Southwest China Railway Research Institute

Industry: Tunnel Engineering & Infrastructure Development

Challenges:

•Extreme excavation depth: The tunnel reaches 115.4 meters below sea level, exposing structures to intense water pressure (1.10 trillion Pa, equivalent to 40 cars per square meter).

•Complex geological conditions: The working section consists of hard granite, requiring drilling and blasting techniques, making accurate excavation monitoring essential.

•Traditional surveying limitations: Conventional total stations, section meters, and stationary scanners require frequent scanning station changes, making the workflow time-consuming and impractical for large-scale tunnel projects.

Artistic rendering of the undersea highway tunnel interior beneath the sea
Artistic rendering of the undersea highway tunnel interior beneath the sea
Inside the highway tunnel under construction with a concrete pump truck and a lit arch ahead
Inside the highway tunnel under construction with a concrete pump truck and a lit arch ahead
Worker installing the steel reinforcement arch of the tunnel lining during construction
Worker installing the steel reinforcement arch of the tunnel lining during construction

Solution Overview

Lixel L2 Pro for High-Precision, Real-Time 3D Scanning

Technology Used:

✔ Lixel L2 Pro Handheld Scanner – Lightweight, mobile LiDAR scanning

✔ Real-Time 3D Modeling – On-device processing for instant visualization

✔ 2CM Accuracy – High-precision point cloud capture without post-processing

Implementation Process:

1️⃣ Rapid 3D Data Capture: The Lixel L2 handheld scanner was deployed on-site, enabling fast and precise data collection across multiple excavation points.

2️⃣ Real-Time Over-Excavation Monitoring: Engineers could immediately assess excavation accuracy on-site, identifying areas requiring correction.

3️⃣ Seamless Integration: The generated point clouds were used for vector drawings and section analysis, allowing project teams to plan the next excavation steps efficiently.

Lixel L2 Pro handheld scanner in its carry case inside the dimly lit construction tunnel
Lixel L2 Pro handheld scanner in its carry case inside the dimly lit construction tunnel
Survey team using the Lixel L2 Pro to 3D scan an excavation face deep inside the tunnel
Survey team using the Lixel L2 Pro to 3D scan an excavation face deep inside the tunnel

Results & Benefits

1️⃣ Enhanced Efficiency & Simplicity

📌 Mobile scanning allows engineers to capture and generate 1-2cm precision 3D models effortlessly.

📌 No station setup required—faster and more flexible compared to traditional static scanners.


2️⃣ Faster Data Output & Decision-Making

📌 Real-time point cloud generation eliminates the need for post-processing.

📌 Immediate data visualization enables quick decision-making for excavation planning.


3️⃣ Reduced Labor & Costs

📌 Single-operator functionality minimizes manpower requirements.

📌 Fewer station relocations reduce project delays and internal costs.


🔹 Record-Breaking Achievement:XGRIDS' Lixel L2 became the deepest handheld LiDAR scanner ever deployed in a tunnel project, reaching 115.4m below sea level.

Colorized point cloud of the tunnel interior captured in real time by the handheld scanner
Colorized point cloud of the tunnel interior captured in real time by the handheld scanner

Lixel L2 Pro: Redefining real-time precision of mobile scanner.

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