Speeding up with mobile mapping
Area 3 is Highways England’s second largest network carrying around 10 per cent of the country’s overall traffic flows. It includes the M27, M3, M4, A3, A303 and the Hindhead Tunnel and provides the main link routes between several major towns and cities including Oxford, London, Reading and Swindon in the north, and Bournemouth, Southampton and Portsmouth in the south.
The large area recently underwent an upgrade to design, replace and install road signage for clearer visibility across the gradients on the road. A topographical survey was needed to capture features for the design. The large scale project required detailed topographical surveys of the carriageway and verges, each survey measuring 600 metres long capturing:
- Carriageway extents
- Road markings
- Crash barriers
- Kerbs and kerb weirs
- Verge levels
- Ironwork frames
- Sign locations
- Traffic loops
- Overhead cables
- Electrical boxes
- Bridge soffit levels
- Pier positions
Sun Hill Surveying and Engineering Ltd., a specialist land surveying and engineering firm, was commissioned by Kier to survey 119 sites on behalf of Highways England Area 3.
From months to day
With more than 30 years’ experience focusing on the civil engineering sector throughout the United Kingdom, Sun Hill brought a modern approach to surveying the large project with its Leica Pegasus:Two mobile mapping platform.
To survey these sites traditionally is a long and protracted operation using laser scanners, total stations and GPS, to collect thousands of points of data per day. Typically, this would take a surveyor around two days per site to complete in the field. Also, to survey this many sites would have required 119 individual traffic management installations.
With a project of this size, there is a significant health and safety risk associated to all involved, to personnel being both in the carriageway and in the verge during all times of the day and night. A safer and more cost effective method was found in the Pegasus:Two to deliver the project on time and in budget.
With mobile mapping, access to all sites was left clear with no road closures as the Pegasus:Two acts in the same way as any other public vehicle when collecting the 3D geospatial data. In total, the surveyors travelled more than 6,000 km using the mobile mapping platform to collect millions of points per second. There was no disruption to the network as traffic management was not required, allowing traffic flow to continue as normal.
Safety to survey personnel was also considerably improved using mobile mapping as no surveyors or traffic management crews were needed in the road as all data was captured from the safety of the vehicle. The surveyors were able to create traditional topographical surveys from point clouds.
"Mobile mapping provided a rapid data capture solution for us," said Peter Bouchard, Sun Hill mobile mapping specialist. "With the Pegasus:Two, we saved time, reduced safety risk and maximised value by reducing a six-plus-month project to 12 days."
Return on mobile mapping investment
As a result of using the Pegasus:Two, all 119 sites were surveyed in only 12 days, with no traffic management, allowing processing and extraction to be undertaken from the safety of an office environment. Furthermore, all 119 sites were surveyed and delivered to Kier a week before the final deadline.
Sun Hill was able to deliver this project with less than 20 mm absolute accuracy. The surveys were then delivered in a staggered program, allowing sites to be prioritised and enabling some sites to be delivered earlier than others.
"At Kier we aim to be at the forefront of technology," said Chris Fuller, Kier Roads Value Stream manager. "The Pegasus:Two is one of the most accurate mobile mapping units on the market. It has helped deliver significant cost savings as well as meaning we could eliminate traffic management completely from the project and all 119 surveys were delivered before the final deadline."