Roads From the Sky

Bluesky perfoms aerial survey of Bere Regis for Buro Happold bypass projectDorsetâs A35 and C6 roads form a crucial link down to the countyâs south coast. To improve this link and relieve seasonal road congestion on over-capacity neighbouring routes, Dorset County Council has commissioned multidisciplinary engineering consultancy Buro Happold to prepare a feasibility study into bypass options for the village of Bere Regis.To accurately understand the levels and features of the local terrain, the consultancy has used UK based aerial imaging and survey specialist Blueskyâs 3D map system which creates digital maps captured by aircraft mounted lasers. Bluesky have also supplied high resolution aerial photography that has been used to create 3D fly-throughs and visualisations of the resulting designs. Using 12d Model, a powerful terrain modelling and civil engineering software package, Buro Happold has expanded on an earlier feasibility study and prepared three options for the bypass. The detailed terrain model has allowed the designers to minimise any impact on the environment, particularly the associated costs of cut and fill operations.âThe size of the study area meant a traditional topographic survey was simply not feasible due to cost implications,â commented Neil Harvey, Senior Engineer in Buro Happoldâs Highways and Infrastructure division. âHowever for the same price as a relatively small ground survey we were able to acquire very accurate terrain measurements and high resolution aerial photography of the entire study area. These have proved instrumental in progressing the feasibility study and preparing designs for each of the three options. The aerial photography will also be fundamental in communicating these designs during a future public consultation period as they provide real world detail to our computer generated models.â In order to capture the highly accurate LiDAR (Light Detection and Ranging) data a survey aircraft equipped with a system of lasers was used. Lasers were beamed to the surface and the time taken for the beam to be bounced back to aircraft-mounted receivers was recorded. Using the known position of the aircraft (derived from on-board satellite positioning equipment), the time taken for the return of the laser beam and the known value of the speed of light, the distance between the aircraft and ground is calculated. Additional readings can also be taken to determine the height of buildings, vegetation and other surface structures. The Bluesky LiDAR data forms part of a detailed 3D terrain map, available online, that covers most of England and Wales including all major urban centres, coastal areas and flood plains. Aerial photography for the whole of England, Wales and parts of Scotland is also available to view and purchase online. BLUESKY LiDAR MAPS FLOOD RISK AREAS FROM THE SKYHighly accurate 3D digital maps, captured from aircraft mounted lasers, are being used to assess the risk of flooding at critical utility sites across the UK. The project, undertaken by Ambiental on behalf of one of the UKâs largest water companies, used LiDAR (Light Detection and Ranging) data supplied by aerial survey specialist Bluesky to help examine the likelihood, extent and depth of potential flooding as part of a review of flood defence measures at each of the five sites.Ambiental, a specialist environmental risk mapping and modelling consultancy, used a combination of existing datasets, models and gauged data in combination with their proprietary modelling and mapping techniques to assess and quantify each flood source in turn. Potential sources of flooding considered during the analysis included fluvial (river), tidal, surface water, sewer and groundwater. The high resolution LiDAR data, supplied by Bluesky, was used to map each risk in 3D to ascertain the spatial distribution of different flood depths. The results of these assessments were used for business planning purposes, specifically within cost-benefit analysis for flood defence measures at each site.LiDAR AT GLANCELiDAR (Light Detection and Ranging) is a highly accurate airborne method of mapping elevation information using aircraft-mounted laser scanners. It works on the same principle as RADAR but uses light waves instead of radio waves. Light sensors in the LiDAR scanner collect the reflected light thereby measuring the distance between the aircraft and the ground, including objects such as buildings and vegetation. LiDAR is a good solution when very high accuracy height measurements are required for large areas. Bluesky can provide off-the-shelf data, with up to 10cm accuracy for many areas across the UK, including most major urban areas as well as rural and flood plain areas.

Author: Iestyn Armstrong-Smith

Bio.: The Marketing Edge, www.themarketingedge.org

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www.bluesky-world.com

TopTen Vol.8, Issue One