Motorway Junction Survey Project Using Mobile Mapping Technology

Woolpert executed a comprehensive motorway junction survey project for the Colas Joint Venture, a leading civil engineering consortium responsible for motorway maintenance across Ireland. The survey targeted junctions number 13 and 14 of the M18 motorway, focusing on delivering detailed and accurate topographical drawings of two sections of the double carriageway road and its associated infrastructure.

Primary Objectives

The primary objective of this project was to produce detailed topographical drawings that included:

• The double carriageway road corridor
• Junction infrastructure (bridges, roundabouts, slip roads, and access roads)

Methodology

Mobile Mapping Technology

The majority of the survey was conducted using advanced mobile mapping technology, which enabled efficient data collection from the motorway and adjacent public roads within a single day.

Key Features of Mobile Mapping Technology:

• High-Speed Data Collection: Enabled rapid surveying with minimal traffic disruption.
• High Accuracy: Achieved accuracy within 10 mm by integrating Ground Control Points.
• Comprehensive Coverage: Captured extensive data points including road surface details and surrounding infrastructure.

Use of Ground Control Points (GCPs):

• GCPs were installed every 100 meters along the road.
• These points were precisely traversed and levelled by a ground crew operating under traffic management protection.
• GCPs were incorporated into the point cloud processing to enhance the accuracy of the survey data.

Ground Survey Crews

Ground crews supported the mobile mapping efforts by surveying areas inaccessible to the mobile mapper, such as:

• Water underpasses
• Terrain relief features outside the road boundary
• The railway line section crossing the motorway (reflectorless survey)

Key Responsibilities of Ground Crews:

• Conduct detailed surveys of specific features not captured by mobile mapping.
• Ensure the accuracy and completeness of topographical data.
• Integrate ground-collected data with mobile mapping data for a seamless topographical representation.

Project Execution

Data Collection

The mobile mapping team used high-resolution LiDAR scanners and panoramic cameras to gather extensive geospatial information along the motorway and public roads. Concurrently, ground crews performed detailed surveys using traditional surveying methods and high-precision GNSS equipment.

Data Processing and Integration

Post-collection, the data underwent rigorous processing, including:

• Preparing accurately georeferenced point cloud.
• 3D CAD model extraction from point cloud.
• Integrating mobile mapping data with ground survey data.

Final Deliverables

The final deliverables provided to Colas Joint Venture included:

• Detailed 3D topographical drawings of the surveyed motorway sections.
• Data visualization on the network portal.

Results and Impact

The project successfully delivered high-quality, detailed topographical data, meeting the client’s specifications. The use of mobile mapping technology significantly enhanced the efficiency and accuracy of the survey, allowing for comprehensive coverage with minimal traffic disruption. The integration of ground survey data ensured that even the most challenging areas were accurately represented.

Key Benefits

• Reduction of Traffic Management Costs: Mobile mapping technology reduced the need for extensive traffic management, lowering overall costs.
• Safety of Work: Enhanced safety by minimizing the time surveyors spent on the road.
• High Efficiency: Enabled rapid data collection and processing.
• Quick Turnaround: Faster delivery of results to the client.
• Additional Products: Provided visual 360-degree panoramic views for enhanced planning and inspection.

Conclusion

The motorway junction survey project conducted by Murphy Geospatial for Colas Joint Venture showcases the effective use of mobile mapping technology in large-scale infrastructure projects. The project’s success demonstrates that using GCPs enables the full benefits of mobile mapping while maintaining high positioning accuracy. This case study highlights the potential for such approaches to revolutionize civil engineering and infrastructure maintenance projects across Ireland and beyond.